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Surgical ablation for atrial fibrillation during isolated coronary artery bypass surgery

Surgical ablation for atrial fibrillation during isolated coronary artery bypass surgery Abstract OBJECTIVES Our goal was to evaluate early sequelae and long-term survival in patients undergoing isolated coronary artery bypass grafting (CABG) with concomitant surgical ablation for atrial fibrillation (AF). METHODS Procedural data from KROK (Polish National Registry of Cardiac Surgery Procedures) were collected. A total of 7879 patients with underlying AF underwent isolated CABG between 2006 and 2018 in 37 reference centres across Poland. The mean follow-up was 4.7 ± 3.5 years [median (interquartile range) 4.3 (1.7–7.4)]. Propensity score matching and Cox proportional hazards models were used to compare isolated CABG + ablation with isolated CABG. RESULTS Of the included patients, 346 (4.39%) underwent surgical ablation. Patients in this group were significantly younger (66.4 ± 7.5 vs 69.2 ± 8.2; P < 0.001) but had a non-significant, different baseline surgical risk (EuroSCORE: 2.11 vs 2.50; P = 0.088). After a rigorous 1:3 propensity matching (LOGIT model: 306 cases of isolated CABG + ablation vs 918 of isolated CABG alone), surgical ablation was associated with a lower 30-day risk of death [risk ratio 0.37, 95% confidence interval (CI) 0.15–0.91; P = 0.032] and multiorgan failure (risk ratio 0.29, 95% CI 0.10–0.94; P = 0.029). In the long term, surgical ablation was associated with a significant 33% improved overall survival rate: hazard ratio 0.67, 95% CI 0.49–0.90; P = 0.008. The benefit of ablation was sustained in the subgroups but was most pronounced in lower risk older patients (age >70 years, P = 0.020; elective status, P = 0.011) with 3-vessel disease (P = 0.036), history of a cerebrovascular accident (P = 0.018) and preserved left ventricular function [left ventricular ejection fraction >50%; P = 0.017; no signs of heart failure (per New York Heart Association functional class); P = 0.001] and those undergoing on-pump CABG (P < 0.001). CONCLUSION Surgical ablation for AF in patients undergoing isolated CABG is safe and associated with significantly improved long-term survival. Coronary artery bypass grafting , Registry , Surgical ablation , Atrial fibrillation INTRODUCTION Unlike mitral valve (MV) surgery, which has a prevalence of surgical ablation performed for atrial fibrillation (AF) of up to 70% and increasing trends seen in the latest Society of Thoracic Surgeons (STS) database report [1], concomitant ablation is performed in ∼30% of patients with AF at the time of coronary artery bypass grafting (CABG). The reasons include the lack of clinically convincing long-term results for surgical ablation in the setting of mostly non-valvular AF and inadequate reimbursement. The 2017 STS Clinical Practice Guidelines for the surgical treatment of AF assigned a class IA recommendation for surgical ablation at the time of concomitant MV operations to restore sinus rhythm [2]. Similarly, a class IB recommendation is assigned for surgical ablation at the time of isolated and combined CABG. Data on long-term safety are, however, lacking. Although several studies addressed the remote efficacy of concomitant surgical ablation with excellent rates of freedom from recurrences of tachyarrhythmias [3–5], only a few randomized trials have been published to date. They all have relatively small sample sizes involving various groupings of patients and inconsistent data in relation to mid- and long-term results [6, 7]. These studies enrolled mostly patients scheduled for combined CABG + MV surgery—thus, the efficacy of surgical ablation in patients undergoing other types of operations, e.g. isolated CABG, is even less well established. The focus of the current analysis was long-term survival results after surgical ablation for AF in patients undergoing isolated CABG. METHODS KROK registry Data were collected in a retrospective fashion from the KROK (Polish National Registry of Cardiac Surgery Procedures) registry (available at: www.krok.csioz.gov.pl). The registry is an ongoing, nationwide, multi-institutional registry of heart surgery procedures in Poland; the details on registry conception and design were described previously [8]. Study population and clinical variables Adult patients undergoing CABG between 2006 and 2018 were identified. Of 189 455 CABG records, we excluded those without a history of AF or without AF at time of presentation. Only isolated CABG operations were included: e.g. concomitant valvular and aortic procedures were excluded; records in which the number of distal anastomoses and/or type of graft material used could not be determined were also excluded. No further exclusion criteria were imposed with regard to patients’ baseline status. For patients undergoing CABG, we considered and reported 3 categories of variables as potentially influencing the primary end point: (i) baseline demographics: age, gender, EuroSCORE [9] and its single components; (ii) extent of coronary artery disease (CAD) and (iii) surgical variables: urgency, operative technique (e.g. on-pump vs off-pump CABG). The primary end point was long-term survival following isolated CABG + ablation versus isolated CABG alone. Analyses of early postoperative (<24 h and 30-day mortality rates) together with in-hospital complications and lengths of stays in the intensive care unit (ICU) and hospital (HLoS) are reported. Statistical analyses Risk ratios (RRs) were used primarily for 30-day/in-hospital outcomes. Cox proportional hazards models were used to determine factors related to the long-term, event-free survival rate. The ensuing statistical models were used to define the point estimates of the hazard ratios (HR) and the 95% confidence intervals (95% CIs) of the effect size. They were also used to evaluate the efficacy of ablation with respect to CABG surgery, first for the univariable Cox proportional hazards model, taking into account all sets of variables categorized by (i) baseline demographics; (ii) extent of CAD; and (iii) surgical characteristics. Next, a multivariable model was built, again stratified on these 3 sets of variables. Interaction between univariable and multivariable models was assessed using the Cochran–Mantel–Haenszel test. The multivariable model was then tested for multicollinearity. A non-parsimonious model including relevant baseline characteristics was proposed [10] for propensity score (PS) matching; the Cox stratified regression model was used to acquire variables for the PS matching model. The overall long-term mortality rate was assessed with Kaplan–Meier curves fitted before (unadjusted model) and after PS matching. As a further sensitivity analysis to assess the survival after concomitant ablation, patients were stratified according to defined subgroups. STATA MP v13.0 software (StataCorp, College Station, TX, USA) and the packages ‘robust’ and ‘CRTgeeDR’ in R Core Team 2013 were used. A detailed description of the statistical analysis is available in the Supplementary Material, Statistical analysis. RESULTS Patient characteristics During the 13-year study period, 189 455 patients undergoing CABG were identified. Of those 7879 initially presented with AF and did not undergo concomitant procedures. The subjects were divided into isolated CABG + ablation [346 (4.39%)] and isolated CABG alone [7533 (95.61%)] (Fig. 1). The mean follow-up period was 4.7 ± 3.5 years [median (interquartile range) 4.3 (1.7–7.4)]. Table 1 lists baseline characteristics and surgical data. Patients in the isolated CABG + ablation group were significantly younger (66.4 ± 7.5 vs 69.2 ± 8.2; P < 0.001) but were at a non-significantly different baseline level of surgical risk (EuroSCORE: 2.11 vs 2.50; P = 0.088). Patients who had isolated CABG + ablation presented more frequently with hyperlipidaemia (P < 0.001) and moderate renal impairment (P = 0.048). The subset with isolated CABG had more diagnoses of left main disease (P = 0.004); more previous myocardial infarctions (P < 0.001); and more previous carotid interventions (P = 0.068) but similar preoperative left ventricular ejection fractions. At the time of the procedure, patients who had isolated CABG + ablation were less commonly in a critical preoperative state (0.6% vs 2.6%; P < 0.001) or had an intra-aortic balloon pump inserted (0.0% vs 2.0%; P = 0.003) compared to the isolated CABG subgroup. The procedure was elective in the majority of included patients [4807 (61.0%)]; of those, 76.3% versus 60.3% were in the isolated CABG + ablation group. The details on operative data are available in Supplementary Material, Table S1. Figure 1: Open in new tabDownload slide Study design. AF: atrial fibrillation; CABG: coronary artery bypass grafting; PS: propensity score. Figure 1: Open in new tabDownload slide Study design. AF: atrial fibrillation; CABG: coronary artery bypass grafting; PS: propensity score. Table 1: Preoperative characteristics before and after propensity score matching Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 a Missing data. ACS: acute coronary syndrome; BMI: body mass index; CABG: coronary artery bypass grafting; CAD: coronary artery disease; CC: creatinine clearance; CCS: Canadian Cardiovascular Society; IQR: interquartile range; LM: left main; LVEF: left ventricle ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; PA: pulmonary artery; PCI: percutaneous coronary intervention; TIA: transient ischaemic attack; VD: vessel disease. Open in new tab Table 1: Preoperative characteristics before and after propensity score matching Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 a Missing data. ACS: acute coronary syndrome; BMI: body mass index; CABG: coronary artery bypass grafting; CAD: coronary artery disease; CC: creatinine clearance; CCS: Canadian Cardiovascular Society; IQR: interquartile range; LM: left main; LVEF: left ventricle ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; PA: pulmonary artery; PCI: percutaneous coronary intervention; TIA: transient ischaemic attack; VD: vessel disease. Open in new tab Operative and early results All patients underwent isolated CABG; concomitant left atrial appendage occlusion was performed and reported in 70 cases (0.9%). Off-pump CABG was preferred over on-pump CABG [4215 (53.5%) vs 3664 (46.5%)]. Left internal mammary artery grafts were used in 79.6% and were used more frequently with isolated CABG + ablation (88.4% vs 79.2%; P < 0.001); a pedicled internal mammary artery was harvested nearly twice as often as a skeletonized internal mammary artery (50.5 vs 29.3%). Complete revascularization was possible in 68.0% of patients and was nearly 8.5% higher in the group undergoing CABG + ablation (P < 0.001). Arterial anastomoses accounted for 41.9% of all distal anastomoses; total arterial revascularization was achieved in 19.7%. The median (interquartile range) HLoS was 10 (8–15) days and the median ICU stay was 2.05 (1.13–3.62) days. The HLoS was no different in the isolated CABG + ablation (standardized mean difference −0.032, 95% CI −0.139 to 0.076; P = 0.567) than in the isolated CABG alone group; length of stay in the ICU was, however, longer in patients undergoing concomitant ablation (standardized mean difference −0.153, 95% CIs −0.261 to −0.045; P = 0.005). The unadjusted RR of the 30-day mortality rate favoured isolated CABG + ablation (HR 0.55, 95% CI 0.30–0.98; P = 0.044). During the 13-year study period, there was a significant survival benefit (HR 0.66, 95% CI 0.51–0.84; P = 0.001) with isolated CABG + ablation compared to isolated CABG alone (Fig. 2). Figure 2: Open in new tabDownload slide Unadjusted Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio. Figure 2: Open in new tabDownload slide Unadjusted Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio. Propensity score analysis A 1–3 PS matched analysis resulted in 306 pairs (306 patients vs 918 patients) with similar baseline and operative characteristics (Table 1 and Supplementary Material, Table S1). The list of variables contributing to the PSs along with the respective PSs is available in Supplementary Material, Table S2. After PS matching, off-pump CABG was performed in 37.6% versus 41.5% (P = 0.226) patients. The use of left internal mammary artery was 81.7% versus 85.4% (P = 0.143) in isolated CABG + ablation versus isolated CABG alone; Complete revascularization (CR) was achieved equally in 79.4% (P = 0.999). Detailed analyses of standardized mean differences before and after PS matching comparing covariate values for patients undergoing isolated CABG + ablation versus isolated CABG alone (Supplementary Material, Fig. S1) suggested a covariate balance across groups. Among PS-matched hospital outcomes, isolated CABG + ablation was associated with a statistically lower risk of 30-day death [respective rates: 5/306 (1.63%) vs 41/918 (4.47%); RR 0.37, 95% CI 0.15–0.91; P = 0.032] and multiorgan failure (RR 0.29, 95% CI 0.10–0.94; P = 0.029). The remaining outcomes did not differ between study groups and are reported in Table 2. PS matched long-term survival was estimated to have an HR of 0.67 (95% CI 0.49–0.90; P = 0.008) (Fig. 3). Figure 3: Open in new tabDownload slide Propensity score matched Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio; PS: propensity score. Figure 3: Open in new tabDownload slide Propensity score matched Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio; PS: propensity score. Table 2: In-hospital outcomes after propensity score matching Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 CABG: coronary artery bypass grafting; CI: confidence interval; ECMO: extracorporeal membrane oxygenation; IABP: intra-aortic balloon pump; ICU: intensive care unit; MI: myocardial infarction; NA: not applicable; PPI: permanent pacemaker implantation. Open in new tab Table 2: In-hospital outcomes after propensity score matching Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 CABG: coronary artery bypass grafting; CI: confidence interval; ECMO: extracorporeal membrane oxygenation; IABP: intra-aortic balloon pump; ICU: intensive care unit; MI: myocardial infarction; NA: not applicable; PPI: permanent pacemaker implantation. Open in new tab Sensitivity and subgroup analyses Supplementary Material, Tables S3 and S4 list the subgroup estimates before and after PS matching. The direction of benefit with concomitant ablation was maintained across subgroups of patients, yet it was particularly pronounced in lower risk older patients (age >70 years; P = 0.020; elective status; P = 0.011) with 3-vessel disease (P = 0.036), history of a cerebrovascular accident (P = 0.018) and preserved left ventricular function (left ventricular ejection fraction > 50%; P = 0.017; no signs of heart failure; P = 0.001). A higher long-term survival benefit in the isolated CABG + ablation group was found in patients undergoing on-pump CABG (HR 0.41, 95% CI 0.28–0.67; P < 0.001) compared to those having off-pump CABG (HR 0.74, 95% CI 0.49–1.13; P = 0.158) (Pint = 0.021). Remaining significant and close-to-significant interactions were found across gender, smoking status, extent of CAD and New York Heart Association classes (Fig. 4). A detailed analysis including both univariable and multivariable Cox proportional hazards models is appended as Supplementary Material, Table S5. Double robust regression model estimates are available as Supplementary Material, Table S6. Figure 4: Open in new tabDownload slide Propensity matched subgroup analysis for the primary end point long-term survival for isolated CABG + ablation compared to isolated CABG alone. CABG: coronary artery bypass grafting; CI: confidence interval; CPB: cardiopulmonary bypass; NYHA: New York Heart Association; OPCAB: off-pump coronary artery bypass; TIA: transient ischaemic attack; VD: vessel disease. Figure 4: Open in new tabDownload slide Propensity matched subgroup analysis for the primary end point long-term survival for isolated CABG + ablation compared to isolated CABG alone. CABG: coronary artery bypass grafting; CI: confidence interval; CPB: cardiopulmonary bypass; NYHA: New York Heart Association; OPCAB: off-pump coronary artery bypass; TIA: transient ischaemic attack; VD: vessel disease. Open in new tabDownload slide Open in new tabDownload slide DISCUSSION Although AF occurs much less frequently in patients undergoing CABG for CAD than in patients having MV surgery, still ∼6% of patients presenting for coronary surgery have preoperative AF [1, 3] regardless of its origin (e.g. valvular vs non-valvular). Preoperative AF was found to be associated with a higher adjusted 30-day mortality rate and greater morbidity rates including those for stroke, renal failure, prolonged ventilation, reoperation and deep sternal wound complications. Patients with preoperative AF also experienced a higher adjusted long-term risk of all-cause death and of a cumulative risk of stroke and systemic embolism compared to those without AF [11, 12]. Unlike MV surgery, with the prevalence of surgical ablation for AF being as high as 70% and increasing trends seen in the latest STS database report [1] and supported in the latest guidelines [2], concomitant ablation is performed in only up to ∼30% of patients with AF at the time of CABG. This report is the first to use the European Registry to assess the safety of surgical ablation for AF performed during isolated CABG on such a scale. A major finding of the analysis is that performing ablation at the time of isolated CABG was associated with a significant long-term survival benefit compared to that achieved when performing isolated CABG alone (HR 0.66, 95% CI 0.51–0.84; P = 0.001). The benefit was maintained after matching for PS (HR 0.67, 95% CI 0.40–0.90; P = 0.008] as well. The extent of the above-reported survival benefit is similar to that observed in the latest PS matching analysis by the group from Washington University in Saint Louis [13] and to that of another KROK analysis performed by our group solely for MV surgery [8] (HR 0.71, 95% CI 0.63–0.79; P < 0.001 for the comparison MV surgery + ablation vs MV surgery alone). Unlike that for MV surgery, assessment of the safety of surgical ablation for AF performed together with CABG is one of the greatest gaps in evidence among heart rhythm operations. Our results fully support this approach in the setting of non-valvular AF as well. To date, several small randomized trials of ablation during CABG are available, with excellent sinus rhythm maintenance rates. Yet, they all suffer from being underpowered for hard clinical outcomes and in particular for long-term outcomes. Among the sparse evidence available to support ablation for AF in CABG are the results of the PRAGUE-12 [14] trial, which compared cardiac surgery with the maze procedure versus cardiac surgery without the maze procedure in patients with coronary and/or valvular heart disease and underlying AF. At 1 year, their results showed sinus rhythm without any AF episodes in 60.2% of patients who had the maze procedure versus 35.5% of the no-maze group (P = 0.002). The addition of surgical ablation to the CABG procedure not only did not compromise early safety (the only significant difference was a longer stay in the ICU), but it was also associated with improved early (30-day) and long-term survival rates. It is worth mentioning that surgical ablation during CABG significantly improved the survival rate from the very first days postoperatively. Curiously, this was not demonstrated in the analysis of ablation concomitant with MV surgery even with the higher number of included ‘ablation patients’, [8] suggesting more pronounced benefits of ablation in CAD than in valvular disease, at least in early postoperative phase. Indeed, in the critically ill patient having cardiac surgery, the loss of sinus rhythm and the atrial contribution to cardiac output can lead to significant haemodynamic instability. In the study by Madershahian et al. [15], patients with AF undergoing CABG had significantly reduced coronary vascular resistance and improved blood flow through the grafts when biventricular pacing wires were applied, thereby minimizing the atrial contribution. Shin et al. [16] went even further and induced AF by high frequency atrial pacing immediately after surgical revascularization in 18 patients who had CABG. AF caused significant deterioration in haemodynamics: Heart rate and central venous pressure increased, and the mean arterial pressure and the cardiac index decreased (P = 0.003). In left internal mammary artery grafts, the flow decreased significantly (P < 0.001) as measured using transit-time flowmetry. By avoiding postoperative AF, the vulnerable grafts are protected against diastolic impairment and the low cardiac output syndrome that is prominent in cases of arrhythmias [17] and are therefore less likely to fail. Corroborating the findings of another analysis by Suwalski et al. [8] in MVs, the benefit of surgical ablation for AF in patients having CABG was much higher in patients at lower risk and most pronounced in older patients (age >70 years; P = 0.020) with 3-vessel disease (P = 0.036) and preserved left ventricular function (left ventricular ejection fraction > 50%; P = 0.017; no signs of heart failure, P = 0.001) and in those undergoing elective CABG (P = 0.034). Interestingly, higher benefits were observed in patients undergoing on-pump CABG: HR 0.40, 95% CI 0.25–0.67; P < 0.001 compared to off-pump CABG with significant statistical interaction between the 2 estimates (Pint = 0.021). It is difficult to discuss the incremental costs of ablation concomitant with CABG in the KROK registry because these are not reimbursed either in Poland or in a majority of European countries [18]. Therefore, surgical ablation performed at the time of isolated CABG is done at the discretion of the physician or is driven by industry-funded research programmes. That phenomenon translated into an unacceptable 4.4% ablation rate in the overall population, which is much lower than that observed in other reports (17–30%) [1, 3, 13]. That said, the current analysis should also be viewed as a potential epidemiological study for payers. To perform surgical ablation at the time of isolated CABG does not compromise safety; it is associated with improved survival and reduced rehospitalization costs, at the same time being financially more attractive for catheter ablation and staged/hybrid procedures [19]. Limitations The limitations of the KROK registry have been described previously [8]. Since the registry itself is a database of general cardiac surgery procedures, several important factors related to approaches to ablation are missing; therefore, a post-hoc survey was conducted in all participating centres to deliver insights on ablation type, energy sources and left atrial appendage management; these results are appended as Supplementary Material. Furthermore, (i) we could not determine the immediate and the long-term efficacy of surgical ablation since these data were not required at the conception of the registry. (ii) Similarly, later conversions to sinus rhythms and maintenance rates are not available; we know from the available literature that patients in whom successful ablation was performed gained higher survival benefits compared to those in whom the ablation was not successful [20]. On the other hand, patients may present with AF up to 3 months postoperatively, which makes the immediate assessment of success inaccurate. (iii) Secondly, left atrial appendage closure rates reported in the current analysis are certainly underestimated, because providing an answer to this query was not obligatory during the conception of the registry. (iv) Lastly, as is the case with registries, other confounders are definitely not accounted for because they were not available from the initial datasets, which may have ‘co-driven’ the long-term results. CONCLUSIONS Surgical ablation for AF in patients undergoing isolated CABG is safe, feasible and associated with significantly improved long-term survival rates. A particular survival benefit was observed in low-risk patients with extensive CAD and those undergoing on-pump CABG. SUPPLEMENTARY MATERIAL Supplementary material is available at EJCTS online. Conflict of interest: none declared. Author contributionsPiotr Suwalski: Conceptualization; Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Mariusz Kowalewski: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualization; Writing—Original draft; Writing—Review & Editing. Marek Jasiński: Conceptualization; Data curation; Investigation; Methodology; Project administration; Validation; Writing—Original draft; Writing—Review & Editing. Jakub Staromłyński: Conceptualization; Data curation; Investigation; Methodology; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Marian Zembala: Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. Kazimierz Widenka: Formal analysis; Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Mirosław Brykczyński: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Jacek Skiba: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Michał Oskar Zembala: Investigation; Methodology; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Krzysztof Bartuś: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Tomasz Hirnle: Investigation; Methodology; Project administration; Validation; Writing—Original draft; Writing—Review & Editing. Inga Dziembowska: Data curation; Formal analysis; Methodology; Resources; Validation; Writing—Original draft; Writing—Review & Editing. Marek Deja: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Zdzisław Tobota: Data curation; Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. Bohdan J. Maruszewski: Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. Presented at the Annual Meeting of the American Association for Thoracic Surgery, Toronto, ON, Canada, 4–7 May 2019. REFERENCES 1 Badhwar V , Rankin JS , Ad N , Grau-Sepulveda M , Damiano RJ , Gillinov AM et al. . Surgical ablation of atrial fibrillation in the United States: trends and propensity matched outcomes . Ann Thorac Surg 2017 ; 104 : 493 – 500 . Google Scholar Crossref Search ADS PubMed WorldCat 2 Badhwar V , Rankin JS , Damiano RJ Jr , Gillinov AM , Bakaeen FG , Edgerton JR et al. . The Society of Thoracic Surgeons 2017 clinical practice guidelines for the surgical treatment of atrial fibrillation . Ann Thorac Surg 2017 ; 103 : 329 – 41 . Google Scholar Crossref Search ADS PubMed WorldCat 3 Gammie JS , Haddad M , Milford-Beland S , Welke KF , Ferguson TB Jr , O'Brien SM et al. . Atrial fibrillation correction surgery: lessons from the Society of Thoracic Surgeons National Cardiac Database . Ann Thorac Surg 2008 ; 85 : 909 – 14 . 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J Thorac Cardiovasc Surg 2012 ; 143 : 1341 – 51 ; discussion 1350–1. Google Scholar Crossref Search ADS PubMed WorldCat ABBREVIATIONS ABBREVIATIONS AF Atrial fibrillation CABG Coronary artery bypass grafting CAD Coronary artery disease CI Confidence interval HR Hazard ratio ICU Intensive care unit MV Mitral valve PS Propensity score RR Risk ratio STS Society of Thoracic Surgeons Author notes The first two authors Mariusz Kowalewski and Piotr Suwalski contributed equally to this study. © The Author(s) 2019. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png European Journal of Cardio-Thoracic Surgery Oxford University Press

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Oxford University Press
Copyright
© The Author(s) 2019. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
ISSN
1010-7940
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1873-734X
DOI
10.1093/ejcts/ezz298
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Abstract

Abstract OBJECTIVES Our goal was to evaluate early sequelae and long-term survival in patients undergoing isolated coronary artery bypass grafting (CABG) with concomitant surgical ablation for atrial fibrillation (AF). METHODS Procedural data from KROK (Polish National Registry of Cardiac Surgery Procedures) were collected. A total of 7879 patients with underlying AF underwent isolated CABG between 2006 and 2018 in 37 reference centres across Poland. The mean follow-up was 4.7 ± 3.5 years [median (interquartile range) 4.3 (1.7–7.4)]. Propensity score matching and Cox proportional hazards models were used to compare isolated CABG + ablation with isolated CABG. RESULTS Of the included patients, 346 (4.39%) underwent surgical ablation. Patients in this group were significantly younger (66.4 ± 7.5 vs 69.2 ± 8.2; P < 0.001) but had a non-significant, different baseline surgical risk (EuroSCORE: 2.11 vs 2.50; P = 0.088). After a rigorous 1:3 propensity matching (LOGIT model: 306 cases of isolated CABG + ablation vs 918 of isolated CABG alone), surgical ablation was associated with a lower 30-day risk of death [risk ratio 0.37, 95% confidence interval (CI) 0.15–0.91; P = 0.032] and multiorgan failure (risk ratio 0.29, 95% CI 0.10–0.94; P = 0.029). In the long term, surgical ablation was associated with a significant 33% improved overall survival rate: hazard ratio 0.67, 95% CI 0.49–0.90; P = 0.008. The benefit of ablation was sustained in the subgroups but was most pronounced in lower risk older patients (age >70 years, P = 0.020; elective status, P = 0.011) with 3-vessel disease (P = 0.036), history of a cerebrovascular accident (P = 0.018) and preserved left ventricular function [left ventricular ejection fraction >50%; P = 0.017; no signs of heart failure (per New York Heart Association functional class); P = 0.001] and those undergoing on-pump CABG (P < 0.001). CONCLUSION Surgical ablation for AF in patients undergoing isolated CABG is safe and associated with significantly improved long-term survival. Coronary artery bypass grafting , Registry , Surgical ablation , Atrial fibrillation INTRODUCTION Unlike mitral valve (MV) surgery, which has a prevalence of surgical ablation performed for atrial fibrillation (AF) of up to 70% and increasing trends seen in the latest Society of Thoracic Surgeons (STS) database report [1], concomitant ablation is performed in ∼30% of patients with AF at the time of coronary artery bypass grafting (CABG). The reasons include the lack of clinically convincing long-term results for surgical ablation in the setting of mostly non-valvular AF and inadequate reimbursement. The 2017 STS Clinical Practice Guidelines for the surgical treatment of AF assigned a class IA recommendation for surgical ablation at the time of concomitant MV operations to restore sinus rhythm [2]. Similarly, a class IB recommendation is assigned for surgical ablation at the time of isolated and combined CABG. Data on long-term safety are, however, lacking. Although several studies addressed the remote efficacy of concomitant surgical ablation with excellent rates of freedom from recurrences of tachyarrhythmias [3–5], only a few randomized trials have been published to date. They all have relatively small sample sizes involving various groupings of patients and inconsistent data in relation to mid- and long-term results [6, 7]. These studies enrolled mostly patients scheduled for combined CABG + MV surgery—thus, the efficacy of surgical ablation in patients undergoing other types of operations, e.g. isolated CABG, is even less well established. The focus of the current analysis was long-term survival results after surgical ablation for AF in patients undergoing isolated CABG. METHODS KROK registry Data were collected in a retrospective fashion from the KROK (Polish National Registry of Cardiac Surgery Procedures) registry (available at: www.krok.csioz.gov.pl). The registry is an ongoing, nationwide, multi-institutional registry of heart surgery procedures in Poland; the details on registry conception and design were described previously [8]. Study population and clinical variables Adult patients undergoing CABG between 2006 and 2018 were identified. Of 189 455 CABG records, we excluded those without a history of AF or without AF at time of presentation. Only isolated CABG operations were included: e.g. concomitant valvular and aortic procedures were excluded; records in which the number of distal anastomoses and/or type of graft material used could not be determined were also excluded. No further exclusion criteria were imposed with regard to patients’ baseline status. For patients undergoing CABG, we considered and reported 3 categories of variables as potentially influencing the primary end point: (i) baseline demographics: age, gender, EuroSCORE [9] and its single components; (ii) extent of coronary artery disease (CAD) and (iii) surgical variables: urgency, operative technique (e.g. on-pump vs off-pump CABG). The primary end point was long-term survival following isolated CABG + ablation versus isolated CABG alone. Analyses of early postoperative (<24 h and 30-day mortality rates) together with in-hospital complications and lengths of stays in the intensive care unit (ICU) and hospital (HLoS) are reported. Statistical analyses Risk ratios (RRs) were used primarily for 30-day/in-hospital outcomes. Cox proportional hazards models were used to determine factors related to the long-term, event-free survival rate. The ensuing statistical models were used to define the point estimates of the hazard ratios (HR) and the 95% confidence intervals (95% CIs) of the effect size. They were also used to evaluate the efficacy of ablation with respect to CABG surgery, first for the univariable Cox proportional hazards model, taking into account all sets of variables categorized by (i) baseline demographics; (ii) extent of CAD; and (iii) surgical characteristics. Next, a multivariable model was built, again stratified on these 3 sets of variables. Interaction between univariable and multivariable models was assessed using the Cochran–Mantel–Haenszel test. The multivariable model was then tested for multicollinearity. A non-parsimonious model including relevant baseline characteristics was proposed [10] for propensity score (PS) matching; the Cox stratified regression model was used to acquire variables for the PS matching model. The overall long-term mortality rate was assessed with Kaplan–Meier curves fitted before (unadjusted model) and after PS matching. As a further sensitivity analysis to assess the survival after concomitant ablation, patients were stratified according to defined subgroups. STATA MP v13.0 software (StataCorp, College Station, TX, USA) and the packages ‘robust’ and ‘CRTgeeDR’ in R Core Team 2013 were used. A detailed description of the statistical analysis is available in the Supplementary Material, Statistical analysis. RESULTS Patient characteristics During the 13-year study period, 189 455 patients undergoing CABG were identified. Of those 7879 initially presented with AF and did not undergo concomitant procedures. The subjects were divided into isolated CABG + ablation [346 (4.39%)] and isolated CABG alone [7533 (95.61%)] (Fig. 1). The mean follow-up period was 4.7 ± 3.5 years [median (interquartile range) 4.3 (1.7–7.4)]. Table 1 lists baseline characteristics and surgical data. Patients in the isolated CABG + ablation group were significantly younger (66.4 ± 7.5 vs 69.2 ± 8.2; P < 0.001) but were at a non-significantly different baseline level of surgical risk (EuroSCORE: 2.11 vs 2.50; P = 0.088). Patients who had isolated CABG + ablation presented more frequently with hyperlipidaemia (P < 0.001) and moderate renal impairment (P = 0.048). The subset with isolated CABG had more diagnoses of left main disease (P = 0.004); more previous myocardial infarctions (P < 0.001); and more previous carotid interventions (P = 0.068) but similar preoperative left ventricular ejection fractions. At the time of the procedure, patients who had isolated CABG + ablation were less commonly in a critical preoperative state (0.6% vs 2.6%; P < 0.001) or had an intra-aortic balloon pump inserted (0.0% vs 2.0%; P = 0.003) compared to the isolated CABG subgroup. The procedure was elective in the majority of included patients [4807 (61.0%)]; of those, 76.3% versus 60.3% were in the isolated CABG + ablation group. The details on operative data are available in Supplementary Material, Table S1. Figure 1: Open in new tabDownload slide Study design. AF: atrial fibrillation; CABG: coronary artery bypass grafting; PS: propensity score. Figure 1: Open in new tabDownload slide Study design. AF: atrial fibrillation; CABG: coronary artery bypass grafting; PS: propensity score. Table 1: Preoperative characteristics before and after propensity score matching Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 a Missing data. ACS: acute coronary syndrome; BMI: body mass index; CABG: coronary artery bypass grafting; CAD: coronary artery disease; CC: creatinine clearance; CCS: Canadian Cardiovascular Society; IQR: interquartile range; LM: left main; LVEF: left ventricle ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; PA: pulmonary artery; PCI: percutaneous coronary intervention; TIA: transient ischaemic attack; VD: vessel disease. Open in new tab Table 1: Preoperative characteristics before and after propensity score matching Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Variables All patients Propensity score matched patients Total (7879) Isolated CABG +  ablation (346) Isolated CABG alone (7533) P-value Total (1224) Isolated CABG +  ablation (306) Isolated CABG alone (918) P-value Baseline characteristics Age (years), median (IQR) 70 (63–75) 62 (61–72) 70 (64–75) <0.001 68 (62–73) 68 (61–72) 67 (60–73) 0.143  <50, n (%) 121 (1.54) 5 (1.44) 116 (1.54) 0.889 57 (4.66) 14 (4.58) 43 (4.68) 0.938  50–70, n (%) 3751 (47.61) 227 (65.61) 3524 (46.78) <0.001 621 (50.74) 155 (50.65) 466 (50.76) 0.974  >70, n (%) 4007 (50.86) 114 (32.95) 3893 (51.68) <0.001 546 (44.61) 137 (42.81) 409 (44.55) 0.550 Gender, n (%)  Male 5991 (76.04) 286 (82.66) 5705 (75.73) 0.003 993 (81.13) 248 (81.05) 745 (81.15) 0.966  Female 1888 (23.96) 60 (17.34) 1828 (24.27) 209 (17.08) 52 (16.99) 157 (17.10) EuroSCORE, median (IQR) 1.35 (0.89–244) 1.36 (0.87–2.31) 1.35 (0.89–2.44) 0.088 1.09 (0.80–1.92) 1.08 (0.80–2.33) 1.09 (0.81–1.92) 0.899  <2, n (%) 120 (1.52) 5 (1.44) 115 (1.52) 0.904 813 (66.42) 203 (66.34) 610 (66.45) 0.972  2–5, n (%) 4050 (51.40) 233 (67.34) 3817 (50.67) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >5, n (%) 3709 (47.07) 108 (31.21) 3601 (47.80) <0.001 5 (0.41) 1 (0.33) 4 (0.44) 0.797 Diabetes, n (%)  Diet only 438 (8.98) 23 (6.65) 415 (5.51) 0.366 93 (7.60) 23 (7.52) 70 (7.63) 0.950  Oral hypoglycaemic drugs 1396 (17.17) 82 (23.70) 1314 (17.44) 0.003 261 (21.32 ) 65 (21.24) 196 (21.35) 0.968  Insulin ± oral hypoglycaemic drugs 1363 (17.30) 51 (14.74) 1312 (17.42) 0.198 197 (16.09) 49 (16.01) 148 (16.12) 0.964 Smoking, n (%) 1048 (13.30) 40 (11.56) 1008 (13.38) 0.329 141 (11.52) 35 (11.44) 106 (11.55) 0.959 Hypertension, n (%) 4104 (52.09) 320 (92.49) 3784 (50.23) 0.138 1101 (89.95) 275 (89.87) 826 (89.98) 0.956 Hyperlipidaemia, n (%) 5007 (63.55) 252 (72.83) 4755 (63.12) <0.001 833 (68.06) 208 (67.97) 625 (68.08) 0.972 Poor mobility, n (%) 398 (5.05) 13 (3.76) 385 (5.11) 0.115 32 (2.61) 7 (2.28) 25 (2.72) 0.933 BMI (kg/m2), median (IQR) 28.4 (25.7–31.5) 29.4 (26.6–32.0) 28.4 (25.7–31.5) 0.104 28. (26.3–31.7) 28.4 (26.0–31.3) 29.0 (26.4–31.9) 0.421 Pulmonary hypertension, n (%)  Moderate (PA systolic 31–55 mmHg) 341 (4.33) 18 (5.20) 323 (4.29) 0.733 65 (5.31) 16 (5.23) 49 (5.34) 0.941  Severe (PA systolic >55 mmHg) 48 (0.61) 0 (0.00) 48 (0.64) 0.114 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Renal impairment, n (%)  Moderate (CC >50 and <85) 1253 (15.90) 77 (22.25) 1176 (15.61) 0.048 249 (20.34) 62 (20.26) 187 (20.37) 0.967  Severe (CC <50) 497 (6.31) 21 (6.07) 476 (6.32) 0.456 81 (6.62) 20 (6.54) 61 (6.64) 0.947  Dialysis (regardless of CC) 41 (0.52) 1 (0.29) 40 (0.53) 0.462 3 (0.25) 1 (0.33) 2 (0.22) 0.740 Peripheral artery disease, n (%) 1238 (15.71) 43 (12.43) 1195 (15.86) 0.085 153 (12.50) 38 (12.42) 115 (12.53) 0.960 Cerebrovascular disease, n (%) 749 (9.51) 29 (8.38) 720 (9.56) 0.465 101 (8.25) 25 (8.17) 76 (8.28) 0.952  History of stroke 302 (3.83) 15 (4.34) 287 (3.81) 0.618 34 (2.78) 9 (2.94) 25 (2.72) 0.841  History of TIA 305 (3.87) 9 (2.60) 296 (3.93) 0.210 29 (2.37) 7 (2.29) 22 (2.40) 0.914  Carotid intervention 112 (1.42) 1 (0.29) 111 (1.47) 0.068 0 (0.00) 0 (0.00) 0 (0.00) 0.999 Chronic lung disease, n (%) 689 (8.74) 29 (8.38) 660 (8.76) 0.808 85 (6.94) 21 (6.86) 64 (6.97) 0.948  Asthma 290 (3.68) 11 (3.18) 279 (3.70) 0.591 37 (3.02) 9 (2.94) 28 (3.05) 0.923 LVEF (%), median (IQR)a 50 (40–55) 50 (41–58) 50 (40–55) 0.090 50 (40–57) 50 (41–57) 50 (40–59) 0.867  <20, n (%) 208 (2.64) 13 (3.76) 195 (2.59) 0.185 25 (2.04) 6 (1.96) 19 (2.07) 0.907  21–30, n (%) 415 (5.27) 11 (3.18) 404 (5.36) 0.082 33 (2.70) 8 (2.61) 25 (2.72) 0.919  31–50, n (%) 2993 (37.99) 134 (38.73) 2859 (37.95) 0.770 833 (68.06) 208 (67.97) 625 (68.08) 0.972  >50, n (%) 4261 (54.08) 186 (53.76) 4075 (54.10) 0.902 337 (27.54) 84 (27.45) 253 (27.56) 0.970 CAD,an (%)  1-VD 689 (8.74) 33 (9.54) 656 (8.71) 0.592 112 (9.15) 28 (9.15) 84 (9.15) 0.950  2-VD 2378 (30.18) 114 (32.95) 2264 (30.05) 0.243 422 (34.48) 99 (32.35) 323 (35.19) 0.972  3-VD 4489 (56.97) 194 (56.07) 4295 (57.02) 0.731 689 (56.29) 179 (58.49) 510 (55.56) 0.974  LM disease 2207 (28.01) 76 (21.97) 2131 (28.29) 0.004 300 (24.51 ) 72 (23.53) 228 (24.84) 0.922 Previous MI, n (%) 4338 (55.06) 140 (40.46) 4198 (55.73) <0.001 409 (33.42) 102 (33.33) 307 (33.44) 0.972  >1 861 (10.90) 31 (8.96) 830 (11.02) 0.229 95 (7.76) 23 (7.52) 72 (7.84) 0.853 Previous PCI 1871 (23.75) 73 (21.10) 1798 (23.87) 0.236 192 (15.69) 49 (16.01) 143 (15.58) 0.856 NYHA functional class, n (%)  0 1061 (13.47) 47 (13.58) 1014 (13.46) 0.948 163 (13.32) 40 (13.07) 123 (13.40) 0.884  I 1655 (21.01) 48 (13.87) 1607 (21.33) 0.001 165 (13.48) 31 (13.40) 124 (13.51) 0.962  II 3660 (46.45) 195 (56.36) 3465 (46.00) <0.001 581 (47.47) 145 (47.39) 436 (47.49) 0.974  III 1234 (15.66) 51 (14.74) 1183 (15.70) 0.629 143 (11.68) 43 (14.05) 100 (10.89) 0.958  IV 269 (3.41) 5 (1.45) 264 (3.50) 0.045 182 (14.87) 47 (15.36) 135 (14.71) 0.781 CCS, n (%)  0 112 (1.42) 5 (1.45) 107 (1.42) 0.970 13 (1.06) 3 (0.98) 10 (1.09) 0.872  1 593 (7.53) 25 (7.23) 568 (7.54) 0.828 76 (6.21) 18 (5.88) 58 (6.32) 0.785  2 2822 (35.82) 145 (41.91) 2677 (35.54) 0.016 483 (39.46) 123 (40.20) 360 (39.22) 0.893  3 3203 (40.65) 146 (42.20) 3057 (40.58) 0.550 536 (43.79) 134 (43.79) 402 (43.79) 0.816  4 899 (11.41) 22 (6.36) 877 (11.64) 0.003 116 (9.48) 28 (9.15) 88 (9.59) 0.779  ACS 250 (3.17) 3 (0.87) 247 (3.28) 0.019 0 (0.00) 0 (0.00) 0 (0.00) 0.999 a Missing data. ACS: acute coronary syndrome; BMI: body mass index; CABG: coronary artery bypass grafting; CAD: coronary artery disease; CC: creatinine clearance; CCS: Canadian Cardiovascular Society; IQR: interquartile range; LM: left main; LVEF: left ventricle ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; PA: pulmonary artery; PCI: percutaneous coronary intervention; TIA: transient ischaemic attack; VD: vessel disease. Open in new tab Operative and early results All patients underwent isolated CABG; concomitant left atrial appendage occlusion was performed and reported in 70 cases (0.9%). Off-pump CABG was preferred over on-pump CABG [4215 (53.5%) vs 3664 (46.5%)]. Left internal mammary artery grafts were used in 79.6% and were used more frequently with isolated CABG + ablation (88.4% vs 79.2%; P < 0.001); a pedicled internal mammary artery was harvested nearly twice as often as a skeletonized internal mammary artery (50.5 vs 29.3%). Complete revascularization was possible in 68.0% of patients and was nearly 8.5% higher in the group undergoing CABG + ablation (P < 0.001). Arterial anastomoses accounted for 41.9% of all distal anastomoses; total arterial revascularization was achieved in 19.7%. The median (interquartile range) HLoS was 10 (8–15) days and the median ICU stay was 2.05 (1.13–3.62) days. The HLoS was no different in the isolated CABG + ablation (standardized mean difference −0.032, 95% CI −0.139 to 0.076; P = 0.567) than in the isolated CABG alone group; length of stay in the ICU was, however, longer in patients undergoing concomitant ablation (standardized mean difference −0.153, 95% CIs −0.261 to −0.045; P = 0.005). The unadjusted RR of the 30-day mortality rate favoured isolated CABG + ablation (HR 0.55, 95% CI 0.30–0.98; P = 0.044). During the 13-year study period, there was a significant survival benefit (HR 0.66, 95% CI 0.51–0.84; P = 0.001) with isolated CABG + ablation compared to isolated CABG alone (Fig. 2). Figure 2: Open in new tabDownload slide Unadjusted Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio. Figure 2: Open in new tabDownload slide Unadjusted Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio. Propensity score analysis A 1–3 PS matched analysis resulted in 306 pairs (306 patients vs 918 patients) with similar baseline and operative characteristics (Table 1 and Supplementary Material, Table S1). The list of variables contributing to the PSs along with the respective PSs is available in Supplementary Material, Table S2. After PS matching, off-pump CABG was performed in 37.6% versus 41.5% (P = 0.226) patients. The use of left internal mammary artery was 81.7% versus 85.4% (P = 0.143) in isolated CABG + ablation versus isolated CABG alone; Complete revascularization (CR) was achieved equally in 79.4% (P = 0.999). Detailed analyses of standardized mean differences before and after PS matching comparing covariate values for patients undergoing isolated CABG + ablation versus isolated CABG alone (Supplementary Material, Fig. S1) suggested a covariate balance across groups. Among PS-matched hospital outcomes, isolated CABG + ablation was associated with a statistically lower risk of 30-day death [respective rates: 5/306 (1.63%) vs 41/918 (4.47%); RR 0.37, 95% CI 0.15–0.91; P = 0.032] and multiorgan failure (RR 0.29, 95% CI 0.10–0.94; P = 0.029). The remaining outcomes did not differ between study groups and are reported in Table 2. PS matched long-term survival was estimated to have an HR of 0.67 (95% CI 0.49–0.90; P = 0.008) (Fig. 3). Figure 3: Open in new tabDownload slide Propensity score matched Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio; PS: propensity score. Figure 3: Open in new tabDownload slide Propensity score matched Kaplan–Meier survival curves between the 2 groups: isolated CABG + ablation versus isolated CABG alone at long-term follow-up. CABG: coronary artery bypass grafting; CI: confidence interval; HR: hazard ratio; PS: propensity score. Table 2: In-hospital outcomes after propensity score matching Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 CABG: coronary artery bypass grafting; CI: confidence interval; ECMO: extracorporeal membrane oxygenation; IABP: intra-aortic balloon pump; ICU: intensive care unit; MI: myocardial infarction; NA: not applicable; PPI: permanent pacemaker implantation. Open in new tab Table 2: In-hospital outcomes after propensity score matching Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 Propensity score matched patients Isolated CABG +  ablation (306), n (%) Isolated CABG alone (918), n (%) Risk ratio (95% CI) P-value Early postoperative death (<24 h) 1 (0.33) 3 (0.33) 1.00 (0.18–5.47) 0.999 30-Day mortality rate 5 (1.63) 41 (4.47) 0.37 (0.15–0.91) 0.032 Cardiac tamponade and/or rethoracotomy 17 (5.56) 45 (4.90) 1.13 (0.66–1.95) 0.651 Periprocedural MI 3 (0.98) 13 (1.42) 0.69 (0.19–2.41) 0.564 Respiratory failure 22 (7.19) 62 (6.75) 1.06 (0.66–1.70) 0.794 Prolonged ICU stay 4 (1.31) 11 (1.20) 1.09 (0.35–3.40) 0.881 Neurological complications 11 (3.59) 34 (3.70) 0.97 (0.49–1.89) 0.930 Multiorgan failure 3 (0.98) 31 (3.38) 0.29 (0.10–0.94) 0.029 Gastrointestinal complications 3 (0.9) 17 (1.85) 0.53 (0.16–1.79) 0.307 Acute kidney failure and/or dialysis 10 (3.27) 38 (5.66) 0.79 (0.40–1.57) 0.498 Superficial sternal wound infection 6 (1.96) 22 (2.40) 0.82 (0.33–1.99) 0.659 Deep sternal wound infection 2 (0.65) 11 (1.20) 0.55 (0.12–2.47) 0.436 Mediastinitis 3 (0.98) 8 (0.87) 1.13 (0.30–4.25) 0.849 PPI 2 (0.65) 2 (0.22) 3.00 (0.42–21.21) 0.271 ECMO 0 (0.00) 0 (0.00) NA NA IABP 11 (3.59) 47 (5.12) 0.70 (0.37–1.33) 0.281 CABG: coronary artery bypass grafting; CI: confidence interval; ECMO: extracorporeal membrane oxygenation; IABP: intra-aortic balloon pump; ICU: intensive care unit; MI: myocardial infarction; NA: not applicable; PPI: permanent pacemaker implantation. Open in new tab Sensitivity and subgroup analyses Supplementary Material, Tables S3 and S4 list the subgroup estimates before and after PS matching. The direction of benefit with concomitant ablation was maintained across subgroups of patients, yet it was particularly pronounced in lower risk older patients (age >70 years; P = 0.020; elective status; P = 0.011) with 3-vessel disease (P = 0.036), history of a cerebrovascular accident (P = 0.018) and preserved left ventricular function (left ventricular ejection fraction > 50%; P = 0.017; no signs of heart failure; P = 0.001). A higher long-term survival benefit in the isolated CABG + ablation group was found in patients undergoing on-pump CABG (HR 0.41, 95% CI 0.28–0.67; P < 0.001) compared to those having off-pump CABG (HR 0.74, 95% CI 0.49–1.13; P = 0.158) (Pint = 0.021). Remaining significant and close-to-significant interactions were found across gender, smoking status, extent of CAD and New York Heart Association classes (Fig. 4). A detailed analysis including both univariable and multivariable Cox proportional hazards models is appended as Supplementary Material, Table S5. Double robust regression model estimates are available as Supplementary Material, Table S6. Figure 4: Open in new tabDownload slide Propensity matched subgroup analysis for the primary end point long-term survival for isolated CABG + ablation compared to isolated CABG alone. CABG: coronary artery bypass grafting; CI: confidence interval; CPB: cardiopulmonary bypass; NYHA: New York Heart Association; OPCAB: off-pump coronary artery bypass; TIA: transient ischaemic attack; VD: vessel disease. Figure 4: Open in new tabDownload slide Propensity matched subgroup analysis for the primary end point long-term survival for isolated CABG + ablation compared to isolated CABG alone. CABG: coronary artery bypass grafting; CI: confidence interval; CPB: cardiopulmonary bypass; NYHA: New York Heart Association; OPCAB: off-pump coronary artery bypass; TIA: transient ischaemic attack; VD: vessel disease. Open in new tabDownload slide Open in new tabDownload slide DISCUSSION Although AF occurs much less frequently in patients undergoing CABG for CAD than in patients having MV surgery, still ∼6% of patients presenting for coronary surgery have preoperative AF [1, 3] regardless of its origin (e.g. valvular vs non-valvular). Preoperative AF was found to be associated with a higher adjusted 30-day mortality rate and greater morbidity rates including those for stroke, renal failure, prolonged ventilation, reoperation and deep sternal wound complications. Patients with preoperative AF also experienced a higher adjusted long-term risk of all-cause death and of a cumulative risk of stroke and systemic embolism compared to those without AF [11, 12]. Unlike MV surgery, with the prevalence of surgical ablation for AF being as high as 70% and increasing trends seen in the latest STS database report [1] and supported in the latest guidelines [2], concomitant ablation is performed in only up to ∼30% of patients with AF at the time of CABG. This report is the first to use the European Registry to assess the safety of surgical ablation for AF performed during isolated CABG on such a scale. A major finding of the analysis is that performing ablation at the time of isolated CABG was associated with a significant long-term survival benefit compared to that achieved when performing isolated CABG alone (HR 0.66, 95% CI 0.51–0.84; P = 0.001). The benefit was maintained after matching for PS (HR 0.67, 95% CI 0.40–0.90; P = 0.008] as well. The extent of the above-reported survival benefit is similar to that observed in the latest PS matching analysis by the group from Washington University in Saint Louis [13] and to that of another KROK analysis performed by our group solely for MV surgery [8] (HR 0.71, 95% CI 0.63–0.79; P < 0.001 for the comparison MV surgery + ablation vs MV surgery alone). Unlike that for MV surgery, assessment of the safety of surgical ablation for AF performed together with CABG is one of the greatest gaps in evidence among heart rhythm operations. Our results fully support this approach in the setting of non-valvular AF as well. To date, several small randomized trials of ablation during CABG are available, with excellent sinus rhythm maintenance rates. Yet, they all suffer from being underpowered for hard clinical outcomes and in particular for long-term outcomes. Among the sparse evidence available to support ablation for AF in CABG are the results of the PRAGUE-12 [14] trial, which compared cardiac surgery with the maze procedure versus cardiac surgery without the maze procedure in patients with coronary and/or valvular heart disease and underlying AF. At 1 year, their results showed sinus rhythm without any AF episodes in 60.2% of patients who had the maze procedure versus 35.5% of the no-maze group (P = 0.002). The addition of surgical ablation to the CABG procedure not only did not compromise early safety (the only significant difference was a longer stay in the ICU), but it was also associated with improved early (30-day) and long-term survival rates. It is worth mentioning that surgical ablation during CABG significantly improved the survival rate from the very first days postoperatively. Curiously, this was not demonstrated in the analysis of ablation concomitant with MV surgery even with the higher number of included ‘ablation patients’, [8] suggesting more pronounced benefits of ablation in CAD than in valvular disease, at least in early postoperative phase. Indeed, in the critically ill patient having cardiac surgery, the loss of sinus rhythm and the atrial contribution to cardiac output can lead to significant haemodynamic instability. In the study by Madershahian et al. [15], patients with AF undergoing CABG had significantly reduced coronary vascular resistance and improved blood flow through the grafts when biventricular pacing wires were applied, thereby minimizing the atrial contribution. Shin et al. [16] went even further and induced AF by high frequency atrial pacing immediately after surgical revascularization in 18 patients who had CABG. AF caused significant deterioration in haemodynamics: Heart rate and central venous pressure increased, and the mean arterial pressure and the cardiac index decreased (P = 0.003). In left internal mammary artery grafts, the flow decreased significantly (P < 0.001) as measured using transit-time flowmetry. By avoiding postoperative AF, the vulnerable grafts are protected against diastolic impairment and the low cardiac output syndrome that is prominent in cases of arrhythmias [17] and are therefore less likely to fail. Corroborating the findings of another analysis by Suwalski et al. [8] in MVs, the benefit of surgical ablation for AF in patients having CABG was much higher in patients at lower risk and most pronounced in older patients (age >70 years; P = 0.020) with 3-vessel disease (P = 0.036) and preserved left ventricular function (left ventricular ejection fraction > 50%; P = 0.017; no signs of heart failure, P = 0.001) and in those undergoing elective CABG (P = 0.034). Interestingly, higher benefits were observed in patients undergoing on-pump CABG: HR 0.40, 95% CI 0.25–0.67; P < 0.001 compared to off-pump CABG with significant statistical interaction between the 2 estimates (Pint = 0.021). It is difficult to discuss the incremental costs of ablation concomitant with CABG in the KROK registry because these are not reimbursed either in Poland or in a majority of European countries [18]. Therefore, surgical ablation performed at the time of isolated CABG is done at the discretion of the physician or is driven by industry-funded research programmes. That phenomenon translated into an unacceptable 4.4% ablation rate in the overall population, which is much lower than that observed in other reports (17–30%) [1, 3, 13]. That said, the current analysis should also be viewed as a potential epidemiological study for payers. To perform surgical ablation at the time of isolated CABG does not compromise safety; it is associated with improved survival and reduced rehospitalization costs, at the same time being financially more attractive for catheter ablation and staged/hybrid procedures [19]. Limitations The limitations of the KROK registry have been described previously [8]. Since the registry itself is a database of general cardiac surgery procedures, several important factors related to approaches to ablation are missing; therefore, a post-hoc survey was conducted in all participating centres to deliver insights on ablation type, energy sources and left atrial appendage management; these results are appended as Supplementary Material. Furthermore, (i) we could not determine the immediate and the long-term efficacy of surgical ablation since these data were not required at the conception of the registry. (ii) Similarly, later conversions to sinus rhythms and maintenance rates are not available; we know from the available literature that patients in whom successful ablation was performed gained higher survival benefits compared to those in whom the ablation was not successful [20]. On the other hand, patients may present with AF up to 3 months postoperatively, which makes the immediate assessment of success inaccurate. (iii) Secondly, left atrial appendage closure rates reported in the current analysis are certainly underestimated, because providing an answer to this query was not obligatory during the conception of the registry. (iv) Lastly, as is the case with registries, other confounders are definitely not accounted for because they were not available from the initial datasets, which may have ‘co-driven’ the long-term results. CONCLUSIONS Surgical ablation for AF in patients undergoing isolated CABG is safe, feasible and associated with significantly improved long-term survival rates. A particular survival benefit was observed in low-risk patients with extensive CAD and those undergoing on-pump CABG. SUPPLEMENTARY MATERIAL Supplementary material is available at EJCTS online. Conflict of interest: none declared. Author contributionsPiotr Suwalski: Conceptualization; Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Mariusz Kowalewski: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualization; Writing—Original draft; Writing—Review & Editing. Marek Jasiński: Conceptualization; Data curation; Investigation; Methodology; Project administration; Validation; Writing—Original draft; Writing—Review & Editing. Jakub Staromłyński: Conceptualization; Data curation; Investigation; Methodology; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Marian Zembala: Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. Kazimierz Widenka: Formal analysis; Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Mirosław Brykczyński: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Jacek Skiba: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Michał Oskar Zembala: Investigation; Methodology; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Krzysztof Bartuś: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Tomasz Hirnle: Investigation; Methodology; Project administration; Validation; Writing—Original draft; Writing—Review & Editing. Inga Dziembowska: Data curation; Formal analysis; Methodology; Resources; Validation; Writing—Original draft; Writing—Review & Editing. Marek Deja: Investigation; Methodology; Project administration; Supervision; Validation; Writing—Original draft; Writing—Review & Editing. Zdzisław Tobota: Data curation; Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. Bohdan J. Maruszewski: Investigation; Methodology; Project administration; Resources; Supervision; Validation; Writing—Original draft; Writing—Review & Editing; registry administration. 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J Thorac Cardiovasc Surg 2012 ; 143 : 1341 – 51 ; discussion 1350–1. Google Scholar Crossref Search ADS PubMed WorldCat ABBREVIATIONS ABBREVIATIONS AF Atrial fibrillation CABG Coronary artery bypass grafting CAD Coronary artery disease CI Confidence interval HR Hazard ratio ICU Intensive care unit MV Mitral valve PS Propensity score RR Risk ratio STS Society of Thoracic Surgeons Author notes The first two authors Mariusz Kowalewski and Piotr Suwalski contributed equally to this study. © The Author(s) 2019. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

European Journal of Cardio-Thoracic SurgeryOxford University Press

Published: Nov 1, 2002

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