What is the optimal target for the second arterial graft in patients undergoing coronary bypass surgery?

What is the optimal target for the second arterial graft in patients undergoing coronary bypass... Abstract A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the anterolateral or the inferior wall served as a better location for the 2nd arterial graft in a 3-system coronary artery bypass grafting procedure. In total, more than 1800 papers were found, of which 6 represented the best evidence to answer the clinical question. All papers demonstrated equivalent early postoperative mortality and morbidity. The 3 largest studies comparing bilateral internal thoracic arteries showed no difference in perioperative mortality and morbidity regardless of whether the 2nd internal thoracic artery was used to graft the left or right system. One of these studies, however, showed significant survival benefit for the left-sided group at 8 years, whereas another study showed a reduced patency of right internal thoracic arteries when grafted to the right coronary artery and when used in situ. One study compared radial grafts to the right- and left-sided targets and showed no difference in long-term patency. Another study also reported on the angiographic patency of right internal thoracic arteries. The authors noted a non-significant increase in graft failure when non-left anterior descending arteries were grafted but no difference between circumflex or posterior descending arteries. All studies demonstrated similar or better mid- and long-term outcomes and patency rates when using the 2nd arterial graft to revascularize left-sided targets when compared with the right. However, all outcomes were similar when comparing non-left anterior descending left-sided targets with non-right coronary artery right-sided targets. Therefore, the right coronary artery itself should probably be avoided as the 2nd arterial target. Coronary artery bypass grafting , Arterial grafts , Target , Review INTRODUCTION A best evidence topic was constructed according to a structured protocol. This is fully described in the ICVTS [1]. THREE-PART QUESTION In patients undergoing 3-vessel coronary artery bypass grafting (CABG) with more than 1 arterial graft, is the anterolateral wall preferable to the inferior wall as a target for the 2nd arterial graft to achieve better patency rates and survival benefit? CLINICAL SCENARIO A 70-year-old non-diabetic patient requiring triple bypass is referred to your service. The targets are the left anterior descending (LAD) artery, the first obtuse marginal artery and the posterior descending artery arising from the right coronary artery (RCA). The stenoses are all >70%. You plan to use the left internal thoracic artery (LITA) to graft the LAD but also plan to use 1 more arterial graft, either the right internal thoracic artery (RITA) or the radial artery (RA), as the patient only has enough venous conduit for 1 target. While you plan to graft the posterior descending artery with the 2nd arterial conduit, your colleague suggests the outcome would be better using this on the obtuse marginal, so you resolve to check the literature yourself. SEARCH STRATEGY We searched MEDLINE from September 1970 to January 2017 using the search terms (‘CABG’ OR ‘coronary artery bypass’) AND (‘arterial’ OR ‘radial’ OR ‘RIMA’ OR ‘RITA’ OR ‘right internal thoracic artery’ OR ‘right internal mammary artery’ OR ‘second internal thoracic artery’ OR ‘second internal mammary artery’) AND (‘location’ OR ‘conduit’ OR ‘target’). SEARCH OUTCOME A total of 1827 papers were found using the reported search. Of these, 6 papers were identified that provided the highest quality evidence to answer the question. These are presented in Table 1. Table 1: Best evidence papers Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    AKI: acute kidney injury; CI: confidence interval; CVA: cerebrovascular accident; DSWI: deep sternal wound infection; IABP: intra-aortic balloon pump; ITA: internal thoracic artery; LAD: left anterior descending; LCS: left coronary system; LITA: left internal thoracic artery; LVEF: left ventricular ejection fraction; MI: myocardial infarction; OM: obtuse marginal; PDA: posterior descending artery; RA: radial artery; RCA: right coronary artery; RCS: right coronary system; RITA: right internal thoracic artery; RR: relative risk. Table 1: Best evidence papers Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    AKI: acute kidney injury; CI: confidence interval; CVA: cerebrovascular accident; DSWI: deep sternal wound infection; IABP: intra-aortic balloon pump; ITA: internal thoracic artery; LAD: left anterior descending; LCS: left coronary system; LITA: left internal thoracic artery; LVEF: left ventricular ejection fraction; MI: myocardial infarction; OM: obtuse marginal; PDA: posterior descending artery; RA: radial artery; RCA: right coronary artery; RCS: right coronary system; RITA: right internal thoracic artery; RR: relative risk. RESULTS Several single-centre studies demonstrate conflicting results regarding the impact of the location of the 2nd arterial graft on clinical outcomes. Schmidt et al. [2] retrospectively analysed data from 498 consecutive patients who underwent CABG with bilateral ITAs. The patients were divided into 2 groups. The first group comprised 311 patients who had the RITA anastomosed to right-sided targets, whereas the 2nd group comprised 187 patients who had the RITA grafted onto left coronary targets. More specifically, the operative strategy in the first group consisted of LITA to LAD and RITA to RCA, whereas in the 2nd group, the RITA was anastomosed to the LAD and the LITA was grafted to the circumflex system. There was an average of 3.4 bypass grafts per patient. A total of 82 ITAs (in 72 patients) were used for sequential grafts, whereas saphenous vein grafts were used to construct the remainder of bypass grafts. The authors found no difference in operative mortality between the groups. Moreover, there was no statistically significant difference in postoperative morbidity. However, during a mean follow-up of 7.1 years, the authors reported a survival benefit for patients in whom the RITA was grafted on a left-sided target. The survival curves began to diverge as early as 6 years, and the survival benefit became significant at 8 years of follow-up. Of the 498 patients included in this study, 89 underwent postoperative angiography at an average of 48.7 (range 1–103) months. Within this small subgroup, there was no difference in the proportion of functionally patent internal thoracic artery grafts between study groups. This study supports the concept that grafting both ITAs to left-sided coronary targets is the preferred strategy when using bilateral ITAs for CABG. Kurlansky et al. [3] studied 2215 patients over a 22-year period. They classified their patients into those who had the 2nd IMA anastomosed to the left coronary system (LCS) (n = 1479 patients) and those who had the IMA grafted onto the right coronary system (RCS) (n = 736 patients). The patients were propensity-matched into 730 pairs, with a mean follow-up of 12.8 years. The authors showed no difference in hospital mortality, perioperative complications and long-term survival between the 2 groups. No statistically significant difference was observed with regard to physical and health summary scores. Sabik et al. [4] studied 3611 patients with 3-vessel coronary artery disease who underwent bilateral ITA grafting with 1 graft anastomosed to the LAD and the 2nd to either the circumflex artery (n = 2926) or the RCA (n = 685). The probability of the 2nd internal thoracic artery grafting was the highest when the stenosis in the recipient artery was in the 70–90% range and decreased to less than 70% and more than 90% stenosis. The authors reported similar in-hospital mortality and long-term survival for both groups regardless of whether the 2nd internal thoracic artery was used to graft the circumflex artery or RCA system. Shah et al. [5] studied 1434 patients who had a CABG procedure and later presented with angina requiring angiogram. A total of 636 RITA symptom-directed angiograms were available for analysis. The authors divided these 636 RITAs between those grafted to the LCS (n = 362) and those which were anastomosed to the RCS (n = 262). They showed that grafts to the RCA had the worst patency, whereas those to the LAD had the best. Grafts to the LCS had better patency than those to the RCS, whereas free RITA grafts had better patency than in situ RITA grafts, regardless of the target artery. Moreover, both RITA and LITA exhibited similar patency rates for each target vessel, except the RCA to which no LITAs were grafted. Buxton et al. [6] assessed the optimal usage of RITA grafts by assessing long-term patency in 432 patients who underwent CABG with the use of a RITA graft and presented with evidence of myocardial ischaemia requiring reangiography at follow-up. The authors examined whether the patency of RITAs depends on the location of the distal anastomosis. The mean age of the patients was 59.6 ± 8.5 years, and the mean reangiography interval was 67.0 ± 39.4 (range 0.1–169.5) months postoperatively. Of the 432 RITA grafts studied, 241 were in situ, and 191 were free grafts. Of the in situ RITA grafts, 123 were to the RCS and 118 to the LCS. There was no statistically significant difference in rates of failure between in situ RITA grafts to the RCS versus in situ RITA grafts to the LCS (relative risk 1.8, 95% confidence interval 0.8–3.8; P = 0.13). Moreover, the authors reported no statistically significant difference in risk of failure in all the RITA graft configurations (diagonal, intermediate, circumflex posterior descending artery and the RCA) when compared with the LAD. Finally, Gaudino et al. [7] published the 20-year results of RA grafts used for CABG in 100 consecutive patients. The authors used the LITA to graft the LAD, whereas the RA was used either in the lateral or in the inferior wall. The authors concluded that the location of the distal anastomosis did not influence long-term angiographic outcomes. More specifically, the patency rate was similar for RA grafts anastomosed to the circumflex, diagonal and RCA. Importantly, this comparison was carried out on a small number of patients, namely 33 long-term survivors who underwent an angiographic control study at a mean period of 19.0 ± 2.5 years after surgery. The target vessel stenosis played a pivotal role in this study as well, as it was shown that a stenosis more than 90% contributed to patency rates similar to that of the LITA, whereas the outcomes for a lower degree of stenosis were more similar to those achieved with saphenous vein grafts. CLINICAL BOTTOM LINE This review attempts to determine the optimal revascularization technique with regard to the location of the 2nd best arterial graft in a 3-system coronary artery disease. There is no consensus on whether the ideal territory should be the anterolateral or the inferior wall. All studies demonstrate similar or better mid- and long-term outcomes and patency rates when using the 2nd arterial graft to revascularize left-sided targets when compared with the right-sided targets. However, all outcomes were similar when comparing non-LAD left-sided targets with non-RCA right-sided targets. Therefore, the RCA itself should probably be avoided as the 2nd arterial target. Conflict of interest: none declared. REFERENCES 1 Dunning J, Prendergast B, Mackway-Jones K. Towards evidence-based medicine in cardiothoracic surgery: best BETS. Interact CardioVasc Thorac Surg  2003; 2: 405– 9. Google Scholar CrossRef Search ADS PubMed  2 Schmidt SE, Jones JW, Thornby JI, Miller CC3rd, Beall ACJr. Improved survival with multiple left-sided bilateral internal thoracic artery grafts. Ann Thorac Surg  1997; 64: 9– 14. Google Scholar CrossRef Search ADS PubMed  3 Kurlansky PA, Traad EA, Dorman MJ, Galbut DL, Zucker M, Ebra G. Location of the second internal mammary artery graft does not influence outcome of coronary artery bypass grafting. Ann Thorac Surg  2011; 91: 1378– 83. Google Scholar CrossRef Search ADS PubMed  4 Sabik JF3rd, Stockins A, Nowicki ER, Blackstone EH, Houghtaling PL, Lytle BW et al.   Does location of the second internal thoracic artery graft influence outcome of coronary artery bypass grafting? Circulation  2008; 118: S210– 5. Google Scholar CrossRef Search ADS PubMed  5 Shah PJ, Durairaj M, Gordon I, Fuller J, Rosalion A, Seevanayagam S et al.   Factors affecting patency of internal thoracic artery graft: clinical and angiographic study in 1434 symptomatic patients operated between 1982 and 2002. Eur J Cardiothorac Surg  2004; 26: 118– 24. Google Scholar CrossRef Search ADS PubMed  6 Buxton BF, Ruengsakulrach P, Fuller J, Rosalion A, Reid CM, Tatoulis J. The right internal thoracic artery graft benefits of grafting the left coronary system and native vessels with a high grade stenosis. Eur J Cardiothorac Surg  2000; 18: 255– 61. Google Scholar CrossRef Search ADS PubMed  7 Gaudino M, Tondi P, Benedetto U, Milazzo V, Flore R, Glieca F et al.   Radial artery as a coronary artery bypass conduit: 20-year results. J Am Coll Cardiol  2016; 68: 603– 10. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018. 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/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Interactive CardioVascular and Thoracic Surgery Oxford University Press

What is the optimal target for the second arterial graft in patients undergoing coronary bypass surgery?

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
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1569-9293
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10.1093/icvts/ivy112
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Abstract

Abstract A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the anterolateral or the inferior wall served as a better location for the 2nd arterial graft in a 3-system coronary artery bypass grafting procedure. In total, more than 1800 papers were found, of which 6 represented the best evidence to answer the clinical question. All papers demonstrated equivalent early postoperative mortality and morbidity. The 3 largest studies comparing bilateral internal thoracic arteries showed no difference in perioperative mortality and morbidity regardless of whether the 2nd internal thoracic artery was used to graft the left or right system. One of these studies, however, showed significant survival benefit for the left-sided group at 8 years, whereas another study showed a reduced patency of right internal thoracic arteries when grafted to the right coronary artery and when used in situ. One study compared radial grafts to the right- and left-sided targets and showed no difference in long-term patency. Another study also reported on the angiographic patency of right internal thoracic arteries. The authors noted a non-significant increase in graft failure when non-left anterior descending arteries were grafted but no difference between circumflex or posterior descending arteries. All studies demonstrated similar or better mid- and long-term outcomes and patency rates when using the 2nd arterial graft to revascularize left-sided targets when compared with the right. However, all outcomes were similar when comparing non-left anterior descending left-sided targets with non-right coronary artery right-sided targets. Therefore, the right coronary artery itself should probably be avoided as the 2nd arterial target. Coronary artery bypass grafting , Arterial grafts , Target , Review INTRODUCTION A best evidence topic was constructed according to a structured protocol. This is fully described in the ICVTS [1]. THREE-PART QUESTION In patients undergoing 3-vessel coronary artery bypass grafting (CABG) with more than 1 arterial graft, is the anterolateral wall preferable to the inferior wall as a target for the 2nd arterial graft to achieve better patency rates and survival benefit? CLINICAL SCENARIO A 70-year-old non-diabetic patient requiring triple bypass is referred to your service. The targets are the left anterior descending (LAD) artery, the first obtuse marginal artery and the posterior descending artery arising from the right coronary artery (RCA). The stenoses are all >70%. You plan to use the left internal thoracic artery (LITA) to graft the LAD but also plan to use 1 more arterial graft, either the right internal thoracic artery (RITA) or the radial artery (RA), as the patient only has enough venous conduit for 1 target. While you plan to graft the posterior descending artery with the 2nd arterial conduit, your colleague suggests the outcome would be better using this on the obtuse marginal, so you resolve to check the literature yourself. SEARCH STRATEGY We searched MEDLINE from September 1970 to January 2017 using the search terms (‘CABG’ OR ‘coronary artery bypass’) AND (‘arterial’ OR ‘radial’ OR ‘RIMA’ OR ‘RITA’ OR ‘right internal thoracic artery’ OR ‘right internal mammary artery’ OR ‘second internal thoracic artery’ OR ‘second internal mammary artery’) AND (‘location’ OR ‘conduit’ OR ‘target’). SEARCH OUTCOME A total of 1827 papers were found using the reported search. Of these, 6 papers were identified that provided the highest quality evidence to answer the question. These are presented in Table 1. Table 1: Best evidence papers Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    AKI: acute kidney injury; CI: confidence interval; CVA: cerebrovascular accident; DSWI: deep sternal wound infection; IABP: intra-aortic balloon pump; ITA: internal thoracic artery; LAD: left anterior descending; LCS: left coronary system; LITA: left internal thoracic artery; LVEF: left ventricular ejection fraction; MI: myocardial infarction; OM: obtuse marginal; PDA: posterior descending artery; RA: radial artery; RCA: right coronary artery; RCS: right coronary system; RITA: right internal thoracic artery; RR: relative risk. Table 1: Best evidence papers Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    Author, date, journal and country Study type (level of evidence)  Patient group  Outcomes  Key results  Comments  Schmidt et al. (1997), Ann Thorac Surg, USA [2] Retrospective study (level II)  n = 498 2nd arterial graft ITA Group 1: n = 311, right side grafting, mean age 60.2 years Group 2: n = 187, left side grafting, mean age 58.6 years Mean follow-up: 7.1 years (mode: 7.3 years)  Preoperative characteristics (Group 1 vs Group 2)  Double-vessel disease: 42.6% vs 32.4% (P = 0.03)   Placing both ITAs to left coronary targets offers good mid-term outcomes and better survival 8 years after the procedure   Left main disease: 9.9% vs 20.2% (P = 0.001)   LVEF <50%: 34.0% vs 43.1% (P = 0.04)   Operative mortality (Group 1 vs Group 2)   1.9% vs 1.1% (P = 0.47)   Morbidity (Group 1 vs Group 2) DSWI   1.0% vs 1.1%   IABP  1.6% vs 2.1%   MI  3.2% vs 1.6%   CVA  1.3% vs 1.1%   Survival at 9.6 years (Group 1 vs Group 2)   70.1% vs 93.1% (P = 0.021)   Functionally patent ITA grafts in 89/498 patients who underwent postoperative angiography (Group 1 vs Group 2)   92% vs 91% (P = 0.81)     Kurlansky et al. (2011), Ann Thorac Surg, USA [3] Retrospective study (level III)  n = 2215 2nd arterial graft ITA n = 730 propensity-matched patients, LCS Mean age: 62.1 ± 10.0 years n = 730 propensity-matched patients, RCS Mean age: 61.7 ± 10.5 years Mean follow-up: 12.8 years (range: 6 weeks–32.1 years)  CCS symptom class at follow-up  CCS Class I or II symptoms (LCS vs RCS) 98.4% vs 96.8% (P = 0.219)   The use of RITA, regardless of the location of the graft (RCS or LCS), was associated with the excellent short- and long-term results There was no difference in operative mortality, hospital morbidity and long-term survival nor in long-term functional status and patient perception of quality of life between RCS and LCS patients  Overall incidence of hospital morbidity including reoperation for bleeding, DSWI, respiratory insufficiency, CVA, AKI, MI, low cardiac output, cardiac arrest and gastrointestinal disorders  Freedom from any in-hospital complication (LCS vs RCS): 622 (85.2%) vs 644 (88.2%)  Length of stay (days, LCS vs RCS)  12.8 ± 15.7 vs 12.4 ± 9.4 (P =0.712)   Hospital mortality (LCS vs RCS)  1.8% vs 2.7% (P = 0.284)       Median survival (years, LCS vs RCS)   16.1 vs 16.1 (P = 0.671)         Quality of Life Health Status assessed using the SF-36 Health Survey         SF-36 physical health summary (LCS vs RCS)  44.8 ± 12.2 vs 46.4 ± 11.7 (P = 0.085)         SF-36 mental health summary (LCS vs RCS)  54.5 ± 7.5 vs 54.1 ± 8.3 (P = 0.442)     Sabik et al. (2008) Circulation, USA [4] Observational study (level II)  n = 3611 2nd arterial graft ITA n = 2926 Circumflex artery Mean age: 56.0 ± 8.4 years n = 685 RCA Mean age: 55.0 ± 8.6 years Mean follow-up: 9.2 ± 7.2 years (median 9.0 years)  1-, 5-, 10-, 15-, and 20-year unadjusted survival estimates (ITA to circumflex artery vs ITA to RCA)  98%, 94%, 86%, 74% and 59% vs 98%, 95%, 87%, 76% and 61% (P = 0.4)   Bilateral ITA grafting is associated with the excellent short- and long-term outcomes regardless of the location of the 2nd ITA (circumflex artery or RCA system)   Hospital death (ITA to circumflex artery vs ITA to RCA)   0.34% vs 0.58% (P = 0.4)   Other hospital outcomes (ITA to circumflex artery vs ITA to RCA)     Stroke  0.96% vs 0.88% (P = 0.8)   MI  1.3% vs 0.73% (P = 0.2)   Renal failure  0.44% vs 0.29% (P = 0.6)   Respiratory failure  3.5% vs 3.8% (P = 0.7)   Re-exploration for bleeding  3.4% vs 3.2% (P = 0.8)     Shah et al. (2004), Eur J Cardiothorac Surg, Australia [5] Retrospective study (level III)  This is a study analysing factors affecting patency of RITA and LITA grafts n = 624 RITAs n = 362 RITAs grafted to LCS (LAD, diagonal, OM) n = 262 RITAs grafted to RCS (PDA, posterolateral, RCA) n = 1461 LITAs (all grafted to the LCS) Mean age: 59 years Mean period from operation to reangiogram: 80 months  Target artery distribution and patency on coronary angiogram  RITA-LAD: n = 93 Patency = 96%   In situ RITA grafts had worse patency than free RITAs, regardless of the target artery Grafts to non-LAD arteries had lower patency rates, with the worst patency seen in the RCA territory The overall patency of the RITA grafts to the left system is almost identical with that of LITA grafts  RITA-diagonal: n = 45 Patency = 93%   RITA-circumflex artery: n = 224 Patency = 90%   RITA-PDA: n = 123 Patency = 87%   RITA-RCA: n = 139 Patency = 79%   LITA-LAD: n = 1193 Patency = 97%   LITA-diagonal: n = 84 Patency = 96%   LITA-intermediate/ circumflex artery: n = 184 Patency = 91%   Buxton et al. (2000), Eur J Cardiothorac Surg, Australia [6] Retrospective study (level ΙΙ)  n = 432 RITA grafts 2nd arterial graft RITA n = 118 in situ RITAs to the LCS n =123 in situ RITAs to the RCS Mean age: 59.6 ± 8.5 years Follow-up: 67.0 ± 39.4 (range 0.1–169.5) months  Graft patency on reangiogram  Risk of failure of in situ RITA to the RCS vs LCS (RR 1.8, 95% CI 0.8–3.8; P = 0.13)   The authors did not report a direct comparison between free RITA grafts to the LCS vs RCS   Risk of failure of RITA-diagonal vs RITA-LAD (RR 2.0, 95% CI 0.3—12.3; P = 0.45)   Risk of failure of RITA-intermediate/circumflex artery vs RITA-LAD (RR 2.8, 95% CI 0.6–12.8; P = 0.17)   Risk of failure of RITA-RCA vs RITA-LAD (RR 4.0, 95% CI 0.9–17.4; P = 0.06)   RITA-PDA/posterolateral vs RITA-LAD (RR 2.6, 95% CI 0.5–2.1; P = 0.19)     Gaudino et al. (2016), J Am Coll Cardiol, Italy [7] Retrospective study (level ΙΙ)  20-Year results of RA and evaluation of patency according to location of distal anastomosis n = 100 patients Mean follow-up 20.8 ± 1.5 years  Long-term RA graft patency on coronary angiography or CT angiography  RA-RCA: n = 10 Patency: 8 patent and 2 occluded (80%)   Location of the distal anastomosis on the circumflex, diagonal or RCA did not influence angiographic RA patency on long-term follow-up. These comparisons were performed on a small number of patients, i.e. 33 patients (of 36 long-term survivors) who underwent an angiographic control study  RA-diagonal: n = 4 Patency: all patent (100%)   RA-circumflex artery: n = 19 Patency: 16 patent and 3 occluded (84%)    AKI: acute kidney injury; CI: confidence interval; CVA: cerebrovascular accident; DSWI: deep sternal wound infection; IABP: intra-aortic balloon pump; ITA: internal thoracic artery; LAD: left anterior descending; LCS: left coronary system; LITA: left internal thoracic artery; LVEF: left ventricular ejection fraction; MI: myocardial infarction; OM: obtuse marginal; PDA: posterior descending artery; RA: radial artery; RCA: right coronary artery; RCS: right coronary system; RITA: right internal thoracic artery; RR: relative risk. RESULTS Several single-centre studies demonstrate conflicting results regarding the impact of the location of the 2nd arterial graft on clinical outcomes. Schmidt et al. [2] retrospectively analysed data from 498 consecutive patients who underwent CABG with bilateral ITAs. The patients were divided into 2 groups. The first group comprised 311 patients who had the RITA anastomosed to right-sided targets, whereas the 2nd group comprised 187 patients who had the RITA grafted onto left coronary targets. More specifically, the operative strategy in the first group consisted of LITA to LAD and RITA to RCA, whereas in the 2nd group, the RITA was anastomosed to the LAD and the LITA was grafted to the circumflex system. There was an average of 3.4 bypass grafts per patient. A total of 82 ITAs (in 72 patients) were used for sequential grafts, whereas saphenous vein grafts were used to construct the remainder of bypass grafts. The authors found no difference in operative mortality between the groups. Moreover, there was no statistically significant difference in postoperative morbidity. However, during a mean follow-up of 7.1 years, the authors reported a survival benefit for patients in whom the RITA was grafted on a left-sided target. The survival curves began to diverge as early as 6 years, and the survival benefit became significant at 8 years of follow-up. Of the 498 patients included in this study, 89 underwent postoperative angiography at an average of 48.7 (range 1–103) months. Within this small subgroup, there was no difference in the proportion of functionally patent internal thoracic artery grafts between study groups. This study supports the concept that grafting both ITAs to left-sided coronary targets is the preferred strategy when using bilateral ITAs for CABG. Kurlansky et al. [3] studied 2215 patients over a 22-year period. They classified their patients into those who had the 2nd IMA anastomosed to the left coronary system (LCS) (n = 1479 patients) and those who had the IMA grafted onto the right coronary system (RCS) (n = 736 patients). The patients were propensity-matched into 730 pairs, with a mean follow-up of 12.8 years. The authors showed no difference in hospital mortality, perioperative complications and long-term survival between the 2 groups. No statistically significant difference was observed with regard to physical and health summary scores. Sabik et al. [4] studied 3611 patients with 3-vessel coronary artery disease who underwent bilateral ITA grafting with 1 graft anastomosed to the LAD and the 2nd to either the circumflex artery (n = 2926) or the RCA (n = 685). The probability of the 2nd internal thoracic artery grafting was the highest when the stenosis in the recipient artery was in the 70–90% range and decreased to less than 70% and more than 90% stenosis. The authors reported similar in-hospital mortality and long-term survival for both groups regardless of whether the 2nd internal thoracic artery was used to graft the circumflex artery or RCA system. Shah et al. [5] studied 1434 patients who had a CABG procedure and later presented with angina requiring angiogram. A total of 636 RITA symptom-directed angiograms were available for analysis. The authors divided these 636 RITAs between those grafted to the LCS (n = 362) and those which were anastomosed to the RCS (n = 262). They showed that grafts to the RCA had the worst patency, whereas those to the LAD had the best. Grafts to the LCS had better patency than those to the RCS, whereas free RITA grafts had better patency than in situ RITA grafts, regardless of the target artery. Moreover, both RITA and LITA exhibited similar patency rates for each target vessel, except the RCA to which no LITAs were grafted. Buxton et al. [6] assessed the optimal usage of RITA grafts by assessing long-term patency in 432 patients who underwent CABG with the use of a RITA graft and presented with evidence of myocardial ischaemia requiring reangiography at follow-up. The authors examined whether the patency of RITAs depends on the location of the distal anastomosis. The mean age of the patients was 59.6 ± 8.5 years, and the mean reangiography interval was 67.0 ± 39.4 (range 0.1–169.5) months postoperatively. Of the 432 RITA grafts studied, 241 were in situ, and 191 were free grafts. Of the in situ RITA grafts, 123 were to the RCS and 118 to the LCS. There was no statistically significant difference in rates of failure between in situ RITA grafts to the RCS versus in situ RITA grafts to the LCS (relative risk 1.8, 95% confidence interval 0.8–3.8; P = 0.13). Moreover, the authors reported no statistically significant difference in risk of failure in all the RITA graft configurations (diagonal, intermediate, circumflex posterior descending artery and the RCA) when compared with the LAD. Finally, Gaudino et al. [7] published the 20-year results of RA grafts used for CABG in 100 consecutive patients. The authors used the LITA to graft the LAD, whereas the RA was used either in the lateral or in the inferior wall. The authors concluded that the location of the distal anastomosis did not influence long-term angiographic outcomes. More specifically, the patency rate was similar for RA grafts anastomosed to the circumflex, diagonal and RCA. Importantly, this comparison was carried out on a small number of patients, namely 33 long-term survivors who underwent an angiographic control study at a mean period of 19.0 ± 2.5 years after surgery. The target vessel stenosis played a pivotal role in this study as well, as it was shown that a stenosis more than 90% contributed to patency rates similar to that of the LITA, whereas the outcomes for a lower degree of stenosis were more similar to those achieved with saphenous vein grafts. CLINICAL BOTTOM LINE This review attempts to determine the optimal revascularization technique with regard to the location of the 2nd best arterial graft in a 3-system coronary artery disease. There is no consensus on whether the ideal territory should be the anterolateral or the inferior wall. All studies demonstrate similar or better mid- and long-term outcomes and patency rates when using the 2nd arterial graft to revascularize left-sided targets when compared with the right-sided targets. However, all outcomes were similar when comparing non-LAD left-sided targets with non-RCA right-sided targets. Therefore, the RCA itself should probably be avoided as the 2nd arterial target. Conflict of interest: none declared. REFERENCES 1 Dunning J, Prendergast B, Mackway-Jones K. Towards evidence-based medicine in cardiothoracic surgery: best BETS. Interact CardioVasc Thorac Surg  2003; 2: 405– 9. Google Scholar CrossRef Search ADS PubMed  2 Schmidt SE, Jones JW, Thornby JI, Miller CC3rd, Beall ACJr. Improved survival with multiple left-sided bilateral internal thoracic artery grafts. Ann Thorac Surg  1997; 64: 9– 14. Google Scholar CrossRef Search ADS PubMed  3 Kurlansky PA, Traad EA, Dorman MJ, Galbut DL, Zucker M, Ebra G. Location of the second internal mammary artery graft does not influence outcome of coronary artery bypass grafting. Ann Thorac Surg  2011; 91: 1378– 83. Google Scholar CrossRef Search ADS PubMed  4 Sabik JF3rd, Stockins A, Nowicki ER, Blackstone EH, Houghtaling PL, Lytle BW et al.   Does location of the second internal thoracic artery graft influence outcome of coronary artery bypass grafting? Circulation  2008; 118: S210– 5. Google Scholar CrossRef Search ADS PubMed  5 Shah PJ, Durairaj M, Gordon I, Fuller J, Rosalion A, Seevanayagam S et al.   Factors affecting patency of internal thoracic artery graft: clinical and angiographic study in 1434 symptomatic patients operated between 1982 and 2002. Eur J Cardiothorac Surg  2004; 26: 118– 24. Google Scholar CrossRef Search ADS PubMed  6 Buxton BF, Ruengsakulrach P, Fuller J, Rosalion A, Reid CM, Tatoulis J. The right internal thoracic artery graft benefits of grafting the left coronary system and native vessels with a high grade stenosis. Eur J Cardiothorac Surg  2000; 18: 255– 61. Google Scholar CrossRef Search ADS PubMed  7 Gaudino M, Tondi P, Benedetto U, Milazzo V, Flore R, Glieca F et al.   Radial artery as a coronary artery bypass conduit: 20-year results. J Am Coll Cardiol  2016; 68: 603– 10. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018. 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/about_us/legal/notices)

Journal

Interactive CardioVascular and Thoracic SurgeryOxford University Press

Published: Apr 5, 2018

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