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Off-Pump vs Conventional Coronary Artery Bypass Grafting: Early and 1-Year Graft Patency, Cost, and Quality-of-Life Outcomes

Off-Pump vs Conventional Coronary Artery Bypass Grafting: Early and 1-Year Graft Patency, Cost,... ContextPrevious trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG).ObjectiveTo assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up.Design, Setting, and PatientsRandomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year.InterventionsOne surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass.The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols.Main Outcome MeasuresCoronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s).ResultsGraft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], −0.66% to 3.31%; P= .19) and at 1 year (absolute difference, −2.2%; 95% CI, −6.1% to 1.7%; P= .27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was $2272 (95% CI, $755-$3732) less for OPCAB (P= .002) and $1955 (95% CI, −$766 to $4727) less at 1 year (P= .08).ConclusionsIn this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.Motivated by morbidity attributable to cardiopulmonary bypass,US surgeons performed approximately 21% of coronary artery bypass operations off-pump in 2002.Nonetheless, concern remains about the technical difficulty of off-pump coronary artery bypass (OPCAB), including the possibility of imprecise anastomoses and incomplete revascularization compromising patient outcomes.Two prospective, randomized studiesand all but a fewretrospective comparisons have reported significantly fewer grafts in OPCAB. Retrospective studies among selected patients showing significant benefits of OPCAB over conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass for mortality,morbidity,length of stay, and costhave been criticized for potential bias in patient selection and management.Previous randomized studies among selected low-risk patientshave reported similar results, but cannot be extrapolated to the general population of CABG patients. The potential clinical and economic advantages of OPCAB in unselected patients and the graft patencies that may be achievable are unknown.The Surgical Management of Arterial Revascularization Therapies (SMART) trial was designed to compare graft patency, clinical outcomes, health-related quality of life, and costs in unselected patients referred for elective, isolated CABG surgery and randomized to OPCAB or CABG with cardiopulmonary bypass. In a preliminary report, patients receiving OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with patients receiving CABG with cardiopulmonary bypass.Results for the primary end point, graft patency prior to hospital discharge and at 1 year, are now reported. Secondary end points include clinical and health-related quality-of-life outcomes and costs during 1-year follow-up.METHODSPatient Enrollment and ManagementIn accordance with the Declaration of Helsinki and with the institutional review board approval granted by Emory University, 200 patients provided written informed consent and were enrolled between March 20, 2000, and August 10, 2001. During this period, 465 patients were referred to a single surgeon (J.D.P.) for isolated primary, elective CABG. An attempt was made to enroll 1 patient each operative day to facilitate accurate and complete data acquisition.Consecutive patients referred each day were screened for eligibility and asked to volunteer until 1 patient had agreed to participate for the following day. Thus, 297 nonconsecutive patients were asked to participate, representing 64% of all referrals. Patients were not excluded for any pattern of coronary artery disease, ventricular dysfunction, or any other comorbidity. Only patients in cardiogenic shock requiring emergency surgery or preoperative intra-aortic balloon pump (inserted at cardiologists' discretion) were excluded for cardiac reasons. Ninety-seven refused to participate. The 200 elective patients randomized comprised 67% of those screened and 43% of all primary elective coronary referrals during the enrollment period (Figure 1).Figure.Flow Diagram of Surgical Management of Arterial Revascularization Therapies (SMART) TrialAll surgery was performed by a single experienced surgeon (J.D.P.) and all patient management was conducted by a single team. Patients, their families, referring cardiologists, and nonoperative clinicians were blinded to treatment strategy for 1 year. Randomization occurred after documentation by the surgeon of the intended optimal revascularization. Patients were randomly assigned by means of a computer-generated random number table and were stratified by sex and diabetic status. Random assignment was performed separately within each stratum with randomly permuted block sizes of 4 and 6. Three patients (1 in the CABG with cardiopulmonary bypass group and 2 in the OPCAB group) were found after randomization to require mitral valve repair or replacement and were withdrawn.Therefore, the study population included 197 patients.Patient management was governed by unbiased and criteria-driven printed protocols that were applied similarly to both groups.Surgical TechniqueIncisions, closure, blood conservation, and suture techniques were similar in all patients. OPCAB was performed with the Medtronic Octopus II or III stabilizing device (Medtronic, Minneapolis, Minn) for coronary stabilization and deep pericardial traction sutures for cardiac displacement.Technical details of surgery for both groups in this trial have been described.All patients received aspirin daily.Graft PatencyGraft angiography was planned prior to hospital discharge and at 1-year follow-up. Only patients with renal insufficiency or severe aortic atherosclerosis were excluded from postoperative angiography for clinical reasons. Three cardiologists, who were blinded to group assignment, simultaneously reviewed angiograms. Each graft was viewed in at least 2 orthogonal planes and scored on the worst appearance of the proximal anastomosis (if any), body of the conduit and distal anastomosis—generating a FitzGibbon scoreby which comparisons were made between groups. A Thrombolysis in Myocardial Infarction flow scorewas also recorded for each graft. A score of 0 indicates no flow or no perfusion; 1, slow penetration without perfusion; 2, partial flow or partial perfusion (>1 but <3); 3, complete and brisk flow or complete perfusion.Left ventriculograms (right anterior oblique projection) from both the preoperative and 1-year follow-up arteriograms were evaluated by a single blinded cardiologist. Left ventricular ejection fraction was calculated by quantitative analysis using the GE Gemnet software (Fairfield, Conn).Follow-up, Quality-of-Life AssessmentAll 192 eligible surviving patients completed a 30-day inperson or telephone interview assessing adverse events, complications, readmissions, and reinterventions. Of 189 (95.9%) patients surviving 365 days, 178 (94.2%) were similarly interviewed at 1-year follow-up. Health-related quality of life was measured using the EuroQol 6and 36-item Medical Outcomes Short-Form Health Survey (SF-36)self-administered questionnaires, which were completed preoperatively and postoperatively at 4 to 6 weeks, 6 months, and 1 year.CostsHospital charges for the index hospitalization were derived from the Medicare formulation of the hospital bill, and costs were calculated using departmental cost-to-charge ratios. Professional costs for the index hospitalization were obtained from Current Procedural Terminology codes, which were converted to relative value units using the resource-based relative value scale.Current Procedural Terminology relative value units were summed and converted to dollars using the Medicare conversion factor. For all rehospitalizations, which tended to occur at other hospitals, diagnosis-related groups were assigned and hospital costs were estimated using average Medicare reimbursement rates. Physician costs for rehospitalizations were estimated as a percentage of hospital costs according to diagnosis-related group and corresponding Medicare physician cost to hospital cost percentages.Power Calculations and Statistical AnalysesThis trial was designed with adequate power (80%; α level of .05) to detect an absolute difference in patency rates between groups in either direction (as small as 5%). All data analysis was according to the intent-to-treat principle. Discrete data are presented as numbers and percentages; continuous data are presented as mean (SD). Dichotomous morbidity and mortality outcomes were analyzed using the Fisher exact test. Analysis of covariance was used to compare postoperative laboratory values and health-related quality-of-life scores between treatment groups after adjusting for preoperative levels. Differences between groups in health-related quality of life were not considered significant at follow-up unless P<.01 (to adjust for the multiple time points of assessment). Dichotomous patency outcomes were analyzed using the Fisher exact test. Overall dichotomous patency rates were analyzed using generalized estimating equationsto account for the potential correlation between patency outcomes within patients. Ordered categorical outcomes were compared between groups using the Cochran-Mantel-Haenszel χ2test. Cost data are presented as mean (SD). Confidence intervals and associated Pvalues for the difference in average costs between treatment groups were obtained using bootstrap resampling.S-PLUS (version 6, Insightful Corp, Seattle, Wash) and SAS (version 8.02, SAS Institute Inc, Cary, NC) statistical software were used for statistical analyses.RESULTSPatient CharacteristicsBaseline characteristics (Table 1) were similar between groups for all measures except previous stroke (more common in CABG with cardiopulmonary bypass) and Canadian Cardiovascular Society angina classifications III and IV (more common in OPCAB).Table 1.Preoperative Patient Characteristics*CharacteristicOff-Pump Coronary Artery BypassCoronary Artery Bypass Graft With Cardiopulmonary BypassPValue†(n = 98)(n = 99)Age, mean (SD), y62.2 (11.1)62.5 (9.45).97Body mass index, mean (SD)‡29.4 (6.0)28.1 (4.5).10Women22 (22.4)23 (23.2)>.99Recent myocardial infarction, d0-714 (14.3)10 (10.1)>7-212 (2.0)2 (2.0).88§>2118 (18.4)21 (21.2)Cerebrovascular accident1 (1.0)9 (9.1).02Transient ischemic attack3 (3.1)1 (1.0).62Chronic obstructive pulmonary disease10 (10.2)8 (8.1).63Current smoker27 (27.6)31 (31.3).64Diabetes&par;Diabetic32 (32.7)33 (33.3)>.99Insulin-treated9 (9.2)10 (10.1)>.99Oral agents22 (22.4)24 (24.2).86Dietary management24 (24.5)21 (21.2).60Hypertension64 (65.3)61 (61.6).65Hypercholesterolemia48 (49.0)47 (47.5)>.99Angioplasty23 (23.5)15 (15.2).21Stent9 (9.2)6 (6.1).43Peripheral vascular surgery13 (13.3)11 (11.1).66Renal failure4 (4.1)2 (2.0).68Dialysis dependent1 (1.0)1 (1.0)>.99NYHA classification III/IV2 (2.0)1 (1.0).62CCS classification III/IV24 (24.5)12 (12.1).03Preoperative medicationsAspirin53 (54.1)57 (57.6).67ACE inhibitor41 (41.8)37 (37.4).56β-Blocker41 (41.8)48 (48.5).39Calcium channel blocker24 (24.5)22 (22.2).74Diuretic16 (16.3)11 (11.1).31Statin40 (40.8)33 (33.3).31(n = 88)¶(n = 91)¶Baseline ejection fraction, %>5546 (52.3)47 (51.6)45-5419 (21.6)20 (22.0)35-4414 (15.9)11 (12.1).7025-345 (5.68)7 (7.69)<254 (4.55)6 (6.59)Abbreviations: ACE, angiotensin-converting enzyme; CCS, Canadian Cardiovascular Society; NYHA, New York Heart Association.*Values are expressed as number (percentage) unless otherwise indicated. Percentages may not total to 100 due to rounding. Baseline values have been reported.19†Fisher exact test for proportions used unless otherwise stated. Wilcoxon rank-sum test used for group comparisons of continuous variables unless otherwise stated. All Pvalues are 2-tailed.‡Measured as weight in kilograms divided by height in meters squared.§Cochran-Mantel-Haenszel test for trend.&par;Categories are not mutually exclusive.¶Number of patients having preoperative (baseline) transesophageal echocardiographic ventricular function data recorded before sternotomy in the operating room.Comparison of risk factors from Table 1for patients enrolled in the SMART trial compared with those patients meeting similar inclusion and exclusion criteria and contemporaneously referred to the study surgeon (J.D.P.) revealed a significant difference only in the proportion of women—45 (22.8%) of 197 trial patients compared with 90 (33.0%) of 268 nontrial patients, which is a 10.2% absolute negative difference (95% confidence interval [CI], 2.0%-18.5%; P= .02). Additional comparison of risk factors from Table 1for patients referred to the study surgeon and for patients meeting similar inclusion and exclusion criteria and referred to the 8 other Emory cardiothoracic surgeons performing CABG with cardiopulmonary bypass revealed few significant differences. The mean (SD) age of the study surgeon's patients was 61.3 (10.7) years, which is 1.7 years younger (95% CI, 0.53-2.8 years; P= .004) than the other surgeons' patients (63.9 [10.8] years). Chronic obstructive pulmonary disease was present in 180 (38.7%) of the study surgeon's 465 patients compared with 334 (17.4%) of the other surgeons' 1921 patients, which is a positive difference of 21.3% (95% CI, 17.5%-25.8%; P<.001). Finally, hypertension was present in 325 (69.9%) of the study surgeon's 465 patients compared with 1468 (76.4%) of the other surgeons' 1921 patients, which is a negative difference of 6.5% (95% CI, 1.2%-10.1%; P= .01). No other significant differences between the study surgeon's patients and the patients of the 8 other Emory surgeons were identified.Three patients assigned to CABG with cardiopulmonary bypass were reassigned to OPCAB due to severe aortic atherosclerosis; 1 patient assigned to OPCAB was reassigned to CABG with cardiopulmonary bypass to graft a deeply intramyocardial coronary artery. Complications within 30 days and 1 year of surgery were similar between groups (Table 2). Twelve patients (8 in the OPCAB group and 4 in the CABG with cardiopulmonary bypass group) were lost to follow-up or withdrew from the study by 1 year. A search of the US Social Security Death Indexrevealed that none of these 12 patients had recorded deaths.Table 2.Early and Late Complications*ComplicationComplications <30 DaysComplications 30 Days to 1 Year†No. (%) of Off-Pump Coronary Artery Bypass Patients (n = 98)No. (%) of CABG With Cardiopulmonary Bypass Patients (n = 99)OR (95% CI)No. (%) of Off-Pump Coronary Artery Bypass Patients (n = 89)No. (%) of CABG With Cardiopulmonary Bypass Patients (n = 93)OR (95% CI)Death (all causes)1 (1.0)2 (2.0)0.50 (0.04-5.61)3 (3.4)2 (2.2)1.58 (0.26-9.73)CardiacReoperation for bleeding1 (1.0)2 (2.0)0.50 (0.04-5.61)00Symptomatic graft occlusion01 (1.0)2 (2.2)1 (1.1)2.11 (0.19-23.7)Angioplasty or stent01 (1.0)2 (2.2)0New Q wave1 (1.0)2 (2.0)0.50 (0.04-5.61)1 (1.1)1 (1.1)1.05 (0.06-17.0)Recurrent angina01 (1.0)3 (3.4)1 (1.1)3.21 (0.33-31.5)New atrial fibrillation16 (16.3)22 (22.2)0.68 (0.33-1.40)01 (1.1)Pacemaker placement0000Congestive heart failure003 (3.4)5 (5.4)0.61 (0.14-2.65)Repeat CABG surgery0000Cardiac readmission1 (1.0)1 (1.0)1.0 (0.06-16.4)11 (12.4)9 (9.7)1.32 (0.52-3.35)NeurologicalPermanent stroke1 (1.0)2 (2.0)0.50 (0.04-5.61)1 (1.1)0Transient ischemic attack1 (1.0)001 (1.1)RenalNew renal failure‡1 (1.0)2 (2.0)0.50 (0.04-5.61)01 (1.1)New dialysis2 (2.0)001 (1.1)PulmonaryPleural effusions requiring thoracentesis9 (9.2)17 (17.2)0.49 (0.21-1.15)00InfectionsDeep sternal§2 (2.0)1 (1.0)2.04 (0.18-22.9)01 (1.1)Superficial sternal&par;4 (4.1)7 (7.1)0.56 (0.16-1.97)00Harvest conduit site&par;9 (9.2)10 (10.1)0.90 (0.35-2.32)00OtherGastrointestinal tract bleed3 (3.1)2 (2.0)1.53 (0.25-9.37)00Noncardiac readmission8 (8.2)9 (9.1)0.89 (0.33-2.41)24 (27.0)25 (27.0)1.00 (0.52-1.93)Abbreviations: CABG, coronary artery bypass graft; CI, confidence interval; OR, odds ratio.*Baseline values have been reported.19†Patients who were alive at 30 days and not withdrawn or lost to follow-up at 1 year.‡Creatinine level higher than 2 mg/dL (176.8 µmol/L) or 50% increase in creatinine level compared with baseline.§Major surgical debridement and/or muscle flap closure and antibiotic treatment.&par;Antibiotic treatment with or without minor incision and drainage.Early Postoperative Graft PatencyOf 197 enrollees, 184 (93.4%) patients had coronary angiography prior to hospital discharge. Angiographic FitzGibbon scores were similar between groups for 622 grafts scored (Table 3). Overall patency rates (FitzGibbon A plus B) were 99.0% for OPCAB and 97.7% for CABG with cardiopulmonary bypass (P= .22 [Fisher exact]; P= .32 [generalized estimating equations]; absolute difference, 1.3% [95% CI, −0.66% to 3.31%]; P= .19). Early patency was similar between groups among all arterial conduits, all venous conduits, and among grafts to each region of the heart. Thrombolysis in Myocardial Infarction flows were also similar between groups (Table 4).Table 3.Early (Inhospital) and Late (1-Year) Arterial and Venous Graft Patency by Coronary Arterial TargetNo. of Grafts With FitzGibbon A or B Score/Total No. of Grafts With Any FitzGibbon Score (%)*Arterial Conduits (n = 250)PValue†Venous Conduits (n = 372)PValue†Off-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassOff-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassLeft anterior descending coronary artery and branches (n = 273)Early90/90 (100)90/90 (100)>.9946/48 (95.8)45/45 (100).501-year69/71 (97.2)76/77 (98.7)>.9934/36 (94.4)35/35 (100).49Right coronary artery and branches (n = 168)Early14/14 (100)12/13 (100).4968/68 (100)69/73 (94.5).121-year11/13 (84.6)10/10 (100).4954/56 (96.4)55/60 (91.7).44Circumflex coronary artery and branches (n = 181)Early22/22 (100)21/21 (100)>.9971/72 (98.6)64/66 (97.0).611-year15/17 (88.2)16/17 (94.1)>.9952/58 (89.7)57/61 (93.4).52All coronary arteries (n = 622)Early126/126 (100)123/124 (99.2)>.99185/188 (98.4)178/184 (96.7).481-year95/101 (94.1)102/104 (98.1).26140/150 (93.3)147/156 (94.2).93Abbreviation: CABG, coronary artery bypass graft.*An "A" on the FitzGibbon scoring system indicates "perfectly patent"; a "B," patent, with any stenosis of less than 50% of the diameter of the target coronary artery; and an "O," totally occluded.22†Pearson χ2test.Table 4.Cross-tabulation of Early (Inhospital) and Late (1-Year) Angiographic Graft Patency Scores*Thrombolysis in Myocardial Infarction Scoring System†No. (%) of Total0123Early (n = 621 Grafts)&par;Off-pump coronary artery bypass (n = 314)‡FitzGibbon O30003 (1)FitzGibbon B00077 (2.2)FitzGibbon A016297304 (97)No. (%) of total grafts3 (1)1 (0.3)6 (2)304 (97)314 (100)CABG with cardiopulmonary bypass (n = 307)§FitzGibbon O70007 (2.3)FitzGibbon B00066 (2.0)FitzGibbon A014289294 (96)No. (%) of total grafts7 (2.3)1 (0.33)4 (1.3)295 (96)307 (100)Late (n = 510 Grafts)&par;Off-pump coronary artery bypass (n = 250)¶FitzGibbon O1600016 (6.4)FitzGibbon B00189 (3.6)FitzGibbon A005220225 (90)No. (%) of total grafts16 (6.4)06 (2.4)228250 (100)CABG with cardiopulmonary bypass (n = 260)#FitzGibbon O1100011 (4.2)FitzGibbon B00044 (1.5)FitzGibbon A011243245 (94)No. (%) of total grafts11 (4.2)1 (0.4)1 (0.4)247 (95)260 (100)Abbreviation: CABG, coronary artery bypass graft.*An "A" on the FitzGibbon scoring system indicates "perfectly patent"; a "B," patent, with any stenosis of less than 50% of the diameter of the target coronary artery; and an "O," totally occluded.†Zero indicates no flow or no perfusion; 1, slow penetration without perfusion; 2, partial flow or partial perfusion (>1 but <3); 3, complete and brisk flow or complete perfusion.‡Of 332 original grafts (94.6%). §Of 337 original grafts (91.1%)&par;Only 621 and 510 grafts are described herein because each of these grafts had both a FitzGibbon score and a Thrombolysis in Myocardial Infarction score recorded.¶Of 332 original grafts (75.3%).#Of 337 original grafts (77.2%).Ten (1.6%) of 622 grafts were occluded at cardiac catheterization prior to hospital discharge. Of these, 3 were in the OPCAB group and 7 were in the CABG with cardiopulmonary bypass group. Nine of the 10 were saphenous vein conduits to non–left anterior descending coronary targets. None of these occluded grafts was associated with recurrent angina or Q-wave myocardial infarction.Graft Patency at 1-Year Follow-upOf the 189 patients who were alive at 1 year, 153 (81%) had coronary angiography a mean (SD) of 384.5 (32) days after surgery (OPCAB group: 385.8 [33]; CABG with cardiopulmonary bypass group: 383.3 [31]). Seven were deemed ineligible due to renal insufficiency (creatinine level >2.5 mg/dL [221 µmol/L]), other medical problems, or social circumstances (3 in OPCAB group and 4 in CABG with cardiopulmonary bypass group) and 17 patients refused follow-up angiography (7 in OPCAB group and 10 in CABG with cardiopulmonary bypass group). Angiographic FitzGibbon scores were similar between groups for 511 grafts scored (Table 3; absolute difference −2.2%; 95% CI, −6.1% to 1.7%; P= .27). Overall, 93.6% of grafts were patent among OPCAB patients compared with 95.8% of the grafts among CABG with cardiopulmonary bypass patients (P= .33 [Fisher exact]; P= .44 [generalized estimating equation]). Patency was similar between groups at 1 year among all arterial conduits, all venous conduits, and among grafts to each region of the heart. Thrombolysis in Myocardial Infarction flows were similar between groups at 1 year (Table 4).Twenty-seven (5.3%) of 511 grafts studied were occluded at 1-year follow-up. Of these, 16 were in OPCAB patients and 11 were in CABG with cardiopulmonary bypass patients. Of these 27 occluded grafts, 19 were saphenous vein conduits to non–left anterior descending coronary targets, while 4 were radial artery grafts and 4 were right or left internal mammary artery grafts.Cardiac End PointsThere were no significant differences between groups in the incidence of death, myocardial infarction, stroke, recurrent angina, readmission for cardiac or noncardiac events, or percutaneous reintervention during hospitalization, at 30 days, or at 1-year follow-up. As of January 2004, no patient has required a surgical reintervention (Table 2).Left ventricular ejection fraction increased significantly (P<.001) in both groups at 1 year compared with baseline preoperative ventriculography (54%-61% in the OPCAB group and 53%-59% in the CABG with cardiopulmonary bypass group).Health-Related Quality of LifeBaseline preoperative SF-36 scores tended to be lower for OPCAB patients and were significantly lower in the General Health Perception subscale and the Mental Component scores. After adjusting for baseline, no significant (P<.01) differences between groups were found for any of the subscale or summary component scores of the SF-36 or the EuroQol 6 scores at any of the follow-up time points (Table 5). There was a trend toward a significant difference in the Social Functioning subscale of the SF-36 at 1 year (P= .049) favoring treatment with OPCAB.Table 5.SF-36 and EuroQol 6 Scores at Baseline and Change From BaselineMean (SD)*PValue†Off-Pump Coronary Artery BypassCABG With Cardiopulmonary Bypass(n = 97)(n = 98)Baseline SF-36 scoresPhysical functioning50.7 (27.9)54.0 (27.2).39Role limitation, physical health28.4 (37.8)31.6 (40.7).56Bodily pain51.0 (25.5)56.8 (26.3).12Social functioning53.2 (19.8)58.4 (20.8).07General health39.2 (23.6)43.0 (24.5).27Role limitation, emotional64.4 (28.3)69.1 (28.2).25Vitality, energy, or fatigue57.0 (45.1)68.4 (41.8).07General health perception66.9 (21.0)75.1 (20.4).007Physical component34.7 (10.3)35.5 (10.8).60Mental component46.4 (12.2)50.6 (11.8).02Baseline EuroQol 6 scores‡Community weights0.73 (0.25)§0.73 (0.23)§.94Visual analog0.60 (0.20)&par;0.62 (0.19)§.51(n = 77)(n = 80)1-Year SF-36 scoresPhysical functioning15.815.6.95Role limitation, physical health36.237.4.84Bodily pain19.417.4.60Social functioning11.66.02.049General health17.813.5.16Role limitation, emotional15.716.4.83Vitality, energy, or fatigue11.512.2.91General health perception6.784.66.40Physical component9.388.71.65Mental component3.252.75.741-Year change from baseline EuroQol 6 scores‡Community weights0.06¶0.074#.66Visual analog0.14**0.15††.63Abbreviations: CABG, coronary artery bypass graft; SF-36, 36-item short form.*One-year SF-36 scores are means that are adjusted for baseline by an analysis of covariance model.†The ttest was used for baseline unpaired data (2-tailed) and analysis of covariance was used to compare changes from baseline at follow-up.‡Community weights are based on utility weights for 5 dimensions of health (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) from a general population in the United Kingdom; visual analog scale is based on a self-rating of current health-related quality of life on a scale of 0 (worst imaginable health state) to 100 (best imaginable health state).§The sample size is 97.&par;The sample size is 96.¶The sample size is 77.#The sample size is 79.**The sample size is 76.††The sample size is 80.CostsThere were 2 patients (both in the OPCAB group) with outlying hospital costs due to severe noncardiac comorbidity (heparin-induced thrombocytopenia and severe Clostridium difficileenterocolitis), which were more than twice the next highest value for the group ($69 883 and $108 353 vs $33 348). Thus, for the primary analysis, hospital costs for these patients were truncated back to the next highest observed value ($33 348). Costs were truncated in the same manner for the patients with the 2 highest observed hospital cost values in the CABG with cardiopulmonary bypass group. Table 6shows results from the overall cost analysis based on truncated data. Mean index hospitalization costs (hospital plus professional costs) were $2272 (95% CI, $755-$3732) lower for the OPCAB group (P= .002). Without truncation of outlying costs, average hospital costs for the index procedure were $18 236 for patients in the CABG with cardiopulmonary bypass group and $17 010 for patients in the OPCAB group (change in cost, $1226 [95% CI, −$1637 to $3575; P= .17). Costs associated with readmission to hospital were similar between groups. The OPCAB treatment remained $1955 (95% CI, −$766 to $4727; P= .08) less expensive on average at 1-year follow-up. Without truncating outlying costs, the difference in 1-year costs was $1266 (95% CI, −$1613 to $3634; P= .16).Table 6.Cost ComparisonOff-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassDifference (95% CI)PValue*(n = 96)(n = 98)Initial hospital cost, mean (SD), US $†Initial cost15 849 (5218)18 080 (4825)2231 (845 to 3625).001Professional cost2947 (1133)2988 (1273)41 (−300 to 385).40Total acute cost18 796 (5552)21 068 (5030)2272 (755 to 3732).002(n = 85)(n = 91)Cumulative hospital costs over 1 y of follow-up, mean (SD), US $‡Initial hospital cost18 618 (4973)20 838 (4879)2220 (751 to 3668).0011-Year follow-up cost4219 (7770)3954 (8334)−265 (−2643 to 2192).59Total 1-year cumulative hospital cost22 837 (9707)24 792 (9140)1955 (−766 to 4727).08Abbreviations: CABG, coronary artery bypass graft; CI, confidence interval.*The bootstrap method was used.†Hospital cost includes all nonprofessional cost categories.‡For all patients with complete 1-year follow-up cost data.COMMENTA preliminary report from the SMART trialdocumented that the mean (SD) number of grafts performed per patient (OPCAB group: 3.39 [1.04]; CABG with cardiopulmonary bypass group: 3.40 [1.08]) and the number of grafts performed per number of grafts intended (index of completeness of revascularization) were similar between groups (OPCAB group: 1.00 [0.18]; CABG with cardiopulmonary bypass group: 1.01 [0.09]). This was the first time that treatment with OPCAB achieved complete revascularization when applied to unselected patients, avoiding the documented negative consequences of incomplete revascularization.Two previous randomized comparisons of OPCAB and CABG with cardiopulmonary bypass have included postoperative angiography. Among low-risk patients, the first study documented angiographic patency among a subset of approximately 25% of enrollees (158 grafts) and reported similar patency rates of 93% for CABG with cardiopulmonary bypass and 91% for OPCAB at 1 year.The second studyreported 3-month angiographic patency rates for 260 grafts among 82 of 103 randomized, low-risk patients. The overall patency rate for grafts performed using conventional CABG was significantly higher than for those performed using OPCAB (98% vs 88%; P= .002). The greatest difference between groups was for patency of radial artery conduits (22/22 [100%] for CABG with cardiopulmonary bypass compared with 26/34 [76%] for OPCAB; P= .01). The 2 surgeons reporting these results had limited experience with OPCAB surgery, having performed only 13% of their isolated coronary bypass procedures off-pump during the preceding 2 years. However, each surgeon was obliged to perform the procedure on each patient in the OPCAB group. Moreover, these surgeons used a relatively low dose of heparin (150 units/kg) in their OPCAB patients and did not supplement that dose intraoperatively.All surgical procedures reported in the present trial were performed by a single experienced OPCAB practitioner, who routinely performs more than 90% of his isolated coronary cases using OPCABand had personal experience in excess of 350 OPCAB cases prior to randomizing patients for this trial. Heparin levels were supplemented at 30-minute intervals. Angiographic results from the SMART trial, obtained in 184 of 197 patients prior to hospital discharge (622 grafts) and 153 of 189 patients at 1 year (511 grafts), demonstrate similar patency and completeness of revascularization in both treatment groups. It is not possible to formally conclude that patency was statistically equivalent between groups; more than 500 patients in each treatment group would have been required to demonstrate such equivalence. Nevertheless, these results suggest that application of OPCAB techniques to unselected patients with multivessel disease need not lead to imprecise anastomoses, nor to a decrement in graft patency.Procoagulant activity may be increased after OPCAB.This phenomenon has been invoked to explain the few isolated reports of diminished vein graft patency after OPCAB.Importantly, patency of saphenous vein grafts was similarly excellent between groups in the present study. Patients in both groups of the SMART trial were treated with perioperative and long-term aspirin; none were prescribed clopidogrel. Nonetheless, awareness of a potential hypercoagulable state among OPCAB patientshas prompted an institutional policy at Emory University since January 2003 of treating OPCAB patients with postoperative clopidogrel for 3 months.Several previous studies have reported improved neuropsychological function after treatment with OPCAB compared with CABG with cardiopulmonary bypass,although this finding has not been uniformly consistent.Results from studies that compared quality-of-life measures after OPCAB and CABG with cardiopulmonary bypass have also been inconsistent.While the weight of peer-reviewed evidence may support the hypothesis that avoidance of cardiopulmonary bypass improves neuropsychological and quality-of-life outcomes after CABG surgery, this important area of investigation remains limited by imprecise assessment toolsand logistical difficulties in performing perioperative testing.Because economic considerations influence medical decision making, the length of stay and cost associated with alternative methods of surgical coronary revascularization are increasingly relevant. With all other acute and long-term outcome measures either similar or superior for the OPCAB group, the decrease in length of stay and cost may influence third-party payers and institutional administrators.The present study has several important limitations. The performance of all surgery by a single surgeon reduced surgical variability, thus making the groups more comparable; but the generalizability of the findings to other surgeons and health care systems has not been proven. No outpatient resource use data was collected during the trial, and thus the evaluation of costs in terms of hospitalization costs alone is limited. However, rehospitalization data capture a large proportion of the costs associated with major adverse events. If OPCAB is associated with lower morbidity compared with CABG with cardiopulmonary bypass, this might be reflected in lower outpatient treatment and medication use for patients receiving OPCAB. Under such circumstances, results based on hospitalization costs alone would yield a conservative estimate of the cost difference between groups.Another important limitation is that 1-year follow-up angiography was only obtained in 78% of the enrolled patients (81% of 1-year survivors). Although there was no systematic difference between the 2 groups regarding lack of 1-year angiography, we cannot exclude the possibility of selection biases affecting our findings. This type of limitation is inherent in trials that require patients to undergo invasive follow-up procedures.These results from the SMART trial demonstrate that OPCAB may provide complete revascularization that is durable and cost-effective relative to CABG with cardiopulmonary bypass when performed on unselected patients undergoing elective, isolated CABG. 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Puskas, MD, MSc, Crawford Long Hospital, Sixth Floor, Medical Office Tower, 550 Peachtree St NE, Atlanta, GA 30308 (john_puskas@emoryhealthcare.org).Author Contributions:Dr Puskas had full access to all of the data in the study and takes full responsibility for the integrity of the data and for the accuracy of the data analysis.Study concept and design:Puskas, Williams, Duke, Marshall, Petersen, Weintraub, Guyton.Acquisition of data:Williams, Huber, Block, Duke, Staples, Marshall, Leimbach, McCall, Bailey.Analysis and interpretation of data:Puskas, Williams, Mahoney, Huber, Block, Glas, Marshall, Leimbach, Weintraub.Drafting of the manuscript:Puskas, Williams, Duke, Marshall, McCall, Petersen, Weintraub.Critical revision of the manuscript for important intellectual content:Puskas, Williams, Mahoney, Huber, Block, Duke, Staples, Glas, Leimbach, Bailey, Weintraub, Guyton.Statistical expertise:Williams, Mahoney, Weintraub.Obtained funding:Puskas, Petersen, Guyton.Administrative, technical, or material support:Williams, Huber, Block, Duke, Marshall, Leimbach, McCall, Petersen, Bailey, Weintraub, Guyton.Supervision:Puskas, Williams, Mahoney, Block, Duke, Staples, Guyton.Funding/Support:The research for this article was supported by grants from Medtronic Inc and the Carlyle Fraser Heart Center Foundation (Atlanta, Ga).Role of the Sponsors:The study sponsors played no role in the design, methods, data management or analysis, nor in the decision to publish. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

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Copyright 2004 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.
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Abstract

ContextPrevious trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG).ObjectiveTo assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up.Design, Setting, and PatientsRandomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year.InterventionsOne surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass.The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols.Main Outcome MeasuresCoronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s).ResultsGraft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], −0.66% to 3.31%; P= .19) and at 1 year (absolute difference, −2.2%; 95% CI, −6.1% to 1.7%; P= .27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was $2272 (95% CI, $755-$3732) less for OPCAB (P= .002) and $1955 (95% CI, −$766 to $4727) less at 1 year (P= .08).ConclusionsIn this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.Motivated by morbidity attributable to cardiopulmonary bypass,US surgeons performed approximately 21% of coronary artery bypass operations off-pump in 2002.Nonetheless, concern remains about the technical difficulty of off-pump coronary artery bypass (OPCAB), including the possibility of imprecise anastomoses and incomplete revascularization compromising patient outcomes.Two prospective, randomized studiesand all but a fewretrospective comparisons have reported significantly fewer grafts in OPCAB. Retrospective studies among selected patients showing significant benefits of OPCAB over conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass for mortality,morbidity,length of stay, and costhave been criticized for potential bias in patient selection and management.Previous randomized studies among selected low-risk patientshave reported similar results, but cannot be extrapolated to the general population of CABG patients. The potential clinical and economic advantages of OPCAB in unselected patients and the graft patencies that may be achievable are unknown.The Surgical Management of Arterial Revascularization Therapies (SMART) trial was designed to compare graft patency, clinical outcomes, health-related quality of life, and costs in unselected patients referred for elective, isolated CABG surgery and randomized to OPCAB or CABG with cardiopulmonary bypass. In a preliminary report, patients receiving OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with patients receiving CABG with cardiopulmonary bypass.Results for the primary end point, graft patency prior to hospital discharge and at 1 year, are now reported. Secondary end points include clinical and health-related quality-of-life outcomes and costs during 1-year follow-up.METHODSPatient Enrollment and ManagementIn accordance with the Declaration of Helsinki and with the institutional review board approval granted by Emory University, 200 patients provided written informed consent and were enrolled between March 20, 2000, and August 10, 2001. During this period, 465 patients were referred to a single surgeon (J.D.P.) for isolated primary, elective CABG. An attempt was made to enroll 1 patient each operative day to facilitate accurate and complete data acquisition.Consecutive patients referred each day were screened for eligibility and asked to volunteer until 1 patient had agreed to participate for the following day. Thus, 297 nonconsecutive patients were asked to participate, representing 64% of all referrals. Patients were not excluded for any pattern of coronary artery disease, ventricular dysfunction, or any other comorbidity. Only patients in cardiogenic shock requiring emergency surgery or preoperative intra-aortic balloon pump (inserted at cardiologists' discretion) were excluded for cardiac reasons. Ninety-seven refused to participate. The 200 elective patients randomized comprised 67% of those screened and 43% of all primary elective coronary referrals during the enrollment period (Figure 1).Figure.Flow Diagram of Surgical Management of Arterial Revascularization Therapies (SMART) TrialAll surgery was performed by a single experienced surgeon (J.D.P.) and all patient management was conducted by a single team. Patients, their families, referring cardiologists, and nonoperative clinicians were blinded to treatment strategy for 1 year. Randomization occurred after documentation by the surgeon of the intended optimal revascularization. Patients were randomly assigned by means of a computer-generated random number table and were stratified by sex and diabetic status. Random assignment was performed separately within each stratum with randomly permuted block sizes of 4 and 6. Three patients (1 in the CABG with cardiopulmonary bypass group and 2 in the OPCAB group) were found after randomization to require mitral valve repair or replacement and were withdrawn.Therefore, the study population included 197 patients.Patient management was governed by unbiased and criteria-driven printed protocols that were applied similarly to both groups.Surgical TechniqueIncisions, closure, blood conservation, and suture techniques were similar in all patients. OPCAB was performed with the Medtronic Octopus II or III stabilizing device (Medtronic, Minneapolis, Minn) for coronary stabilization and deep pericardial traction sutures for cardiac displacement.Technical details of surgery for both groups in this trial have been described.All patients received aspirin daily.Graft PatencyGraft angiography was planned prior to hospital discharge and at 1-year follow-up. Only patients with renal insufficiency or severe aortic atherosclerosis were excluded from postoperative angiography for clinical reasons. Three cardiologists, who were blinded to group assignment, simultaneously reviewed angiograms. Each graft was viewed in at least 2 orthogonal planes and scored on the worst appearance of the proximal anastomosis (if any), body of the conduit and distal anastomosis—generating a FitzGibbon scoreby which comparisons were made between groups. A Thrombolysis in Myocardial Infarction flow scorewas also recorded for each graft. A score of 0 indicates no flow or no perfusion; 1, slow penetration without perfusion; 2, partial flow or partial perfusion (>1 but <3); 3, complete and brisk flow or complete perfusion.Left ventriculograms (right anterior oblique projection) from both the preoperative and 1-year follow-up arteriograms were evaluated by a single blinded cardiologist. Left ventricular ejection fraction was calculated by quantitative analysis using the GE Gemnet software (Fairfield, Conn).Follow-up, Quality-of-Life AssessmentAll 192 eligible surviving patients completed a 30-day inperson or telephone interview assessing adverse events, complications, readmissions, and reinterventions. Of 189 (95.9%) patients surviving 365 days, 178 (94.2%) were similarly interviewed at 1-year follow-up. Health-related quality of life was measured using the EuroQol 6and 36-item Medical Outcomes Short-Form Health Survey (SF-36)self-administered questionnaires, which were completed preoperatively and postoperatively at 4 to 6 weeks, 6 months, and 1 year.CostsHospital charges for the index hospitalization were derived from the Medicare formulation of the hospital bill, and costs were calculated using departmental cost-to-charge ratios. Professional costs for the index hospitalization were obtained from Current Procedural Terminology codes, which were converted to relative value units using the resource-based relative value scale.Current Procedural Terminology relative value units were summed and converted to dollars using the Medicare conversion factor. For all rehospitalizations, which tended to occur at other hospitals, diagnosis-related groups were assigned and hospital costs were estimated using average Medicare reimbursement rates. Physician costs for rehospitalizations were estimated as a percentage of hospital costs according to diagnosis-related group and corresponding Medicare physician cost to hospital cost percentages.Power Calculations and Statistical AnalysesThis trial was designed with adequate power (80%; α level of .05) to detect an absolute difference in patency rates between groups in either direction (as small as 5%). All data analysis was according to the intent-to-treat principle. Discrete data are presented as numbers and percentages; continuous data are presented as mean (SD). Dichotomous morbidity and mortality outcomes were analyzed using the Fisher exact test. Analysis of covariance was used to compare postoperative laboratory values and health-related quality-of-life scores between treatment groups after adjusting for preoperative levels. Differences between groups in health-related quality of life were not considered significant at follow-up unless P<.01 (to adjust for the multiple time points of assessment). Dichotomous patency outcomes were analyzed using the Fisher exact test. Overall dichotomous patency rates were analyzed using generalized estimating equationsto account for the potential correlation between patency outcomes within patients. Ordered categorical outcomes were compared between groups using the Cochran-Mantel-Haenszel χ2test. Cost data are presented as mean (SD). Confidence intervals and associated Pvalues for the difference in average costs between treatment groups were obtained using bootstrap resampling.S-PLUS (version 6, Insightful Corp, Seattle, Wash) and SAS (version 8.02, SAS Institute Inc, Cary, NC) statistical software were used for statistical analyses.RESULTSPatient CharacteristicsBaseline characteristics (Table 1) were similar between groups for all measures except previous stroke (more common in CABG with cardiopulmonary bypass) and Canadian Cardiovascular Society angina classifications III and IV (more common in OPCAB).Table 1.Preoperative Patient Characteristics*CharacteristicOff-Pump Coronary Artery BypassCoronary Artery Bypass Graft With Cardiopulmonary BypassPValue†(n = 98)(n = 99)Age, mean (SD), y62.2 (11.1)62.5 (9.45).97Body mass index, mean (SD)‡29.4 (6.0)28.1 (4.5).10Women22 (22.4)23 (23.2)>.99Recent myocardial infarction, d0-714 (14.3)10 (10.1)>7-212 (2.0)2 (2.0).88§>2118 (18.4)21 (21.2)Cerebrovascular accident1 (1.0)9 (9.1).02Transient ischemic attack3 (3.1)1 (1.0).62Chronic obstructive pulmonary disease10 (10.2)8 (8.1).63Current smoker27 (27.6)31 (31.3).64Diabetes&par;Diabetic32 (32.7)33 (33.3)>.99Insulin-treated9 (9.2)10 (10.1)>.99Oral agents22 (22.4)24 (24.2).86Dietary management24 (24.5)21 (21.2).60Hypertension64 (65.3)61 (61.6).65Hypercholesterolemia48 (49.0)47 (47.5)>.99Angioplasty23 (23.5)15 (15.2).21Stent9 (9.2)6 (6.1).43Peripheral vascular surgery13 (13.3)11 (11.1).66Renal failure4 (4.1)2 (2.0).68Dialysis dependent1 (1.0)1 (1.0)>.99NYHA classification III/IV2 (2.0)1 (1.0).62CCS classification III/IV24 (24.5)12 (12.1).03Preoperative medicationsAspirin53 (54.1)57 (57.6).67ACE inhibitor41 (41.8)37 (37.4).56β-Blocker41 (41.8)48 (48.5).39Calcium channel blocker24 (24.5)22 (22.2).74Diuretic16 (16.3)11 (11.1).31Statin40 (40.8)33 (33.3).31(n = 88)¶(n = 91)¶Baseline ejection fraction, %>5546 (52.3)47 (51.6)45-5419 (21.6)20 (22.0)35-4414 (15.9)11 (12.1).7025-345 (5.68)7 (7.69)<254 (4.55)6 (6.59)Abbreviations: ACE, angiotensin-converting enzyme; CCS, Canadian Cardiovascular Society; NYHA, New York Heart Association.*Values are expressed as number (percentage) unless otherwise indicated. Percentages may not total to 100 due to rounding. Baseline values have been reported.19†Fisher exact test for proportions used unless otherwise stated. Wilcoxon rank-sum test used for group comparisons of continuous variables unless otherwise stated. All Pvalues are 2-tailed.‡Measured as weight in kilograms divided by height in meters squared.§Cochran-Mantel-Haenszel test for trend.&par;Categories are not mutually exclusive.¶Number of patients having preoperative (baseline) transesophageal echocardiographic ventricular function data recorded before sternotomy in the operating room.Comparison of risk factors from Table 1for patients enrolled in the SMART trial compared with those patients meeting similar inclusion and exclusion criteria and contemporaneously referred to the study surgeon (J.D.P.) revealed a significant difference only in the proportion of women—45 (22.8%) of 197 trial patients compared with 90 (33.0%) of 268 nontrial patients, which is a 10.2% absolute negative difference (95% confidence interval [CI], 2.0%-18.5%; P= .02). Additional comparison of risk factors from Table 1for patients referred to the study surgeon and for patients meeting similar inclusion and exclusion criteria and referred to the 8 other Emory cardiothoracic surgeons performing CABG with cardiopulmonary bypass revealed few significant differences. The mean (SD) age of the study surgeon's patients was 61.3 (10.7) years, which is 1.7 years younger (95% CI, 0.53-2.8 years; P= .004) than the other surgeons' patients (63.9 [10.8] years). Chronic obstructive pulmonary disease was present in 180 (38.7%) of the study surgeon's 465 patients compared with 334 (17.4%) of the other surgeons' 1921 patients, which is a positive difference of 21.3% (95% CI, 17.5%-25.8%; P<.001). Finally, hypertension was present in 325 (69.9%) of the study surgeon's 465 patients compared with 1468 (76.4%) of the other surgeons' 1921 patients, which is a negative difference of 6.5% (95% CI, 1.2%-10.1%; P= .01). No other significant differences between the study surgeon's patients and the patients of the 8 other Emory surgeons were identified.Three patients assigned to CABG with cardiopulmonary bypass were reassigned to OPCAB due to severe aortic atherosclerosis; 1 patient assigned to OPCAB was reassigned to CABG with cardiopulmonary bypass to graft a deeply intramyocardial coronary artery. Complications within 30 days and 1 year of surgery were similar between groups (Table 2). Twelve patients (8 in the OPCAB group and 4 in the CABG with cardiopulmonary bypass group) were lost to follow-up or withdrew from the study by 1 year. A search of the US Social Security Death Indexrevealed that none of these 12 patients had recorded deaths.Table 2.Early and Late Complications*ComplicationComplications <30 DaysComplications 30 Days to 1 Year†No. (%) of Off-Pump Coronary Artery Bypass Patients (n = 98)No. (%) of CABG With Cardiopulmonary Bypass Patients (n = 99)OR (95% CI)No. (%) of Off-Pump Coronary Artery Bypass Patients (n = 89)No. (%) of CABG With Cardiopulmonary Bypass Patients (n = 93)OR (95% CI)Death (all causes)1 (1.0)2 (2.0)0.50 (0.04-5.61)3 (3.4)2 (2.2)1.58 (0.26-9.73)CardiacReoperation for bleeding1 (1.0)2 (2.0)0.50 (0.04-5.61)00Symptomatic graft occlusion01 (1.0)2 (2.2)1 (1.1)2.11 (0.19-23.7)Angioplasty or stent01 (1.0)2 (2.2)0New Q wave1 (1.0)2 (2.0)0.50 (0.04-5.61)1 (1.1)1 (1.1)1.05 (0.06-17.0)Recurrent angina01 (1.0)3 (3.4)1 (1.1)3.21 (0.33-31.5)New atrial fibrillation16 (16.3)22 (22.2)0.68 (0.33-1.40)01 (1.1)Pacemaker placement0000Congestive heart failure003 (3.4)5 (5.4)0.61 (0.14-2.65)Repeat CABG surgery0000Cardiac readmission1 (1.0)1 (1.0)1.0 (0.06-16.4)11 (12.4)9 (9.7)1.32 (0.52-3.35)NeurologicalPermanent stroke1 (1.0)2 (2.0)0.50 (0.04-5.61)1 (1.1)0Transient ischemic attack1 (1.0)001 (1.1)RenalNew renal failure‡1 (1.0)2 (2.0)0.50 (0.04-5.61)01 (1.1)New dialysis2 (2.0)001 (1.1)PulmonaryPleural effusions requiring thoracentesis9 (9.2)17 (17.2)0.49 (0.21-1.15)00InfectionsDeep sternal§2 (2.0)1 (1.0)2.04 (0.18-22.9)01 (1.1)Superficial sternal&par;4 (4.1)7 (7.1)0.56 (0.16-1.97)00Harvest conduit site&par;9 (9.2)10 (10.1)0.90 (0.35-2.32)00OtherGastrointestinal tract bleed3 (3.1)2 (2.0)1.53 (0.25-9.37)00Noncardiac readmission8 (8.2)9 (9.1)0.89 (0.33-2.41)24 (27.0)25 (27.0)1.00 (0.52-1.93)Abbreviations: CABG, coronary artery bypass graft; CI, confidence interval; OR, odds ratio.*Baseline values have been reported.19†Patients who were alive at 30 days and not withdrawn or lost to follow-up at 1 year.‡Creatinine level higher than 2 mg/dL (176.8 µmol/L) or 50% increase in creatinine level compared with baseline.§Major surgical debridement and/or muscle flap closure and antibiotic treatment.&par;Antibiotic treatment with or without minor incision and drainage.Early Postoperative Graft PatencyOf 197 enrollees, 184 (93.4%) patients had coronary angiography prior to hospital discharge. Angiographic FitzGibbon scores were similar between groups for 622 grafts scored (Table 3). Overall patency rates (FitzGibbon A plus B) were 99.0% for OPCAB and 97.7% for CABG with cardiopulmonary bypass (P= .22 [Fisher exact]; P= .32 [generalized estimating equations]; absolute difference, 1.3% [95% CI, −0.66% to 3.31%]; P= .19). Early patency was similar between groups among all arterial conduits, all venous conduits, and among grafts to each region of the heart. Thrombolysis in Myocardial Infarction flows were also similar between groups (Table 4).Table 3.Early (Inhospital) and Late (1-Year) Arterial and Venous Graft Patency by Coronary Arterial TargetNo. of Grafts With FitzGibbon A or B Score/Total No. of Grafts With Any FitzGibbon Score (%)*Arterial Conduits (n = 250)PValue†Venous Conduits (n = 372)PValue†Off-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassOff-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassLeft anterior descending coronary artery and branches (n = 273)Early90/90 (100)90/90 (100)>.9946/48 (95.8)45/45 (100).501-year69/71 (97.2)76/77 (98.7)>.9934/36 (94.4)35/35 (100).49Right coronary artery and branches (n = 168)Early14/14 (100)12/13 (100).4968/68 (100)69/73 (94.5).121-year11/13 (84.6)10/10 (100).4954/56 (96.4)55/60 (91.7).44Circumflex coronary artery and branches (n = 181)Early22/22 (100)21/21 (100)>.9971/72 (98.6)64/66 (97.0).611-year15/17 (88.2)16/17 (94.1)>.9952/58 (89.7)57/61 (93.4).52All coronary arteries (n = 622)Early126/126 (100)123/124 (99.2)>.99185/188 (98.4)178/184 (96.7).481-year95/101 (94.1)102/104 (98.1).26140/150 (93.3)147/156 (94.2).93Abbreviation: CABG, coronary artery bypass graft.*An "A" on the FitzGibbon scoring system indicates "perfectly patent"; a "B," patent, with any stenosis of less than 50% of the diameter of the target coronary artery; and an "O," totally occluded.22†Pearson χ2test.Table 4.Cross-tabulation of Early (Inhospital) and Late (1-Year) Angiographic Graft Patency Scores*Thrombolysis in Myocardial Infarction Scoring System†No. (%) of Total0123Early (n = 621 Grafts)&par;Off-pump coronary artery bypass (n = 314)‡FitzGibbon O30003 (1)FitzGibbon B00077 (2.2)FitzGibbon A016297304 (97)No. (%) of total grafts3 (1)1 (0.3)6 (2)304 (97)314 (100)CABG with cardiopulmonary bypass (n = 307)§FitzGibbon O70007 (2.3)FitzGibbon B00066 (2.0)FitzGibbon A014289294 (96)No. (%) of total grafts7 (2.3)1 (0.33)4 (1.3)295 (96)307 (100)Late (n = 510 Grafts)&par;Off-pump coronary artery bypass (n = 250)¶FitzGibbon O1600016 (6.4)FitzGibbon B00189 (3.6)FitzGibbon A005220225 (90)No. (%) of total grafts16 (6.4)06 (2.4)228250 (100)CABG with cardiopulmonary bypass (n = 260)#FitzGibbon O1100011 (4.2)FitzGibbon B00044 (1.5)FitzGibbon A011243245 (94)No. (%) of total grafts11 (4.2)1 (0.4)1 (0.4)247 (95)260 (100)Abbreviation: CABG, coronary artery bypass graft.*An "A" on the FitzGibbon scoring system indicates "perfectly patent"; a "B," patent, with any stenosis of less than 50% of the diameter of the target coronary artery; and an "O," totally occluded.†Zero indicates no flow or no perfusion; 1, slow penetration without perfusion; 2, partial flow or partial perfusion (>1 but <3); 3, complete and brisk flow or complete perfusion.‡Of 332 original grafts (94.6%). §Of 337 original grafts (91.1%)&par;Only 621 and 510 grafts are described herein because each of these grafts had both a FitzGibbon score and a Thrombolysis in Myocardial Infarction score recorded.¶Of 332 original grafts (75.3%).#Of 337 original grafts (77.2%).Ten (1.6%) of 622 grafts were occluded at cardiac catheterization prior to hospital discharge. Of these, 3 were in the OPCAB group and 7 were in the CABG with cardiopulmonary bypass group. Nine of the 10 were saphenous vein conduits to non–left anterior descending coronary targets. None of these occluded grafts was associated with recurrent angina or Q-wave myocardial infarction.Graft Patency at 1-Year Follow-upOf the 189 patients who were alive at 1 year, 153 (81%) had coronary angiography a mean (SD) of 384.5 (32) days after surgery (OPCAB group: 385.8 [33]; CABG with cardiopulmonary bypass group: 383.3 [31]). Seven were deemed ineligible due to renal insufficiency (creatinine level >2.5 mg/dL [221 µmol/L]), other medical problems, or social circumstances (3 in OPCAB group and 4 in CABG with cardiopulmonary bypass group) and 17 patients refused follow-up angiography (7 in OPCAB group and 10 in CABG with cardiopulmonary bypass group). Angiographic FitzGibbon scores were similar between groups for 511 grafts scored (Table 3; absolute difference −2.2%; 95% CI, −6.1% to 1.7%; P= .27). Overall, 93.6% of grafts were patent among OPCAB patients compared with 95.8% of the grafts among CABG with cardiopulmonary bypass patients (P= .33 [Fisher exact]; P= .44 [generalized estimating equation]). Patency was similar between groups at 1 year among all arterial conduits, all venous conduits, and among grafts to each region of the heart. Thrombolysis in Myocardial Infarction flows were similar between groups at 1 year (Table 4).Twenty-seven (5.3%) of 511 grafts studied were occluded at 1-year follow-up. Of these, 16 were in OPCAB patients and 11 were in CABG with cardiopulmonary bypass patients. Of these 27 occluded grafts, 19 were saphenous vein conduits to non–left anterior descending coronary targets, while 4 were radial artery grafts and 4 were right or left internal mammary artery grafts.Cardiac End PointsThere were no significant differences between groups in the incidence of death, myocardial infarction, stroke, recurrent angina, readmission for cardiac or noncardiac events, or percutaneous reintervention during hospitalization, at 30 days, or at 1-year follow-up. As of January 2004, no patient has required a surgical reintervention (Table 2).Left ventricular ejection fraction increased significantly (P<.001) in both groups at 1 year compared with baseline preoperative ventriculography (54%-61% in the OPCAB group and 53%-59% in the CABG with cardiopulmonary bypass group).Health-Related Quality of LifeBaseline preoperative SF-36 scores tended to be lower for OPCAB patients and were significantly lower in the General Health Perception subscale and the Mental Component scores. After adjusting for baseline, no significant (P<.01) differences between groups were found for any of the subscale or summary component scores of the SF-36 or the EuroQol 6 scores at any of the follow-up time points (Table 5). There was a trend toward a significant difference in the Social Functioning subscale of the SF-36 at 1 year (P= .049) favoring treatment with OPCAB.Table 5.SF-36 and EuroQol 6 Scores at Baseline and Change From BaselineMean (SD)*PValue†Off-Pump Coronary Artery BypassCABG With Cardiopulmonary Bypass(n = 97)(n = 98)Baseline SF-36 scoresPhysical functioning50.7 (27.9)54.0 (27.2).39Role limitation, physical health28.4 (37.8)31.6 (40.7).56Bodily pain51.0 (25.5)56.8 (26.3).12Social functioning53.2 (19.8)58.4 (20.8).07General health39.2 (23.6)43.0 (24.5).27Role limitation, emotional64.4 (28.3)69.1 (28.2).25Vitality, energy, or fatigue57.0 (45.1)68.4 (41.8).07General health perception66.9 (21.0)75.1 (20.4).007Physical component34.7 (10.3)35.5 (10.8).60Mental component46.4 (12.2)50.6 (11.8).02Baseline EuroQol 6 scores‡Community weights0.73 (0.25)§0.73 (0.23)§.94Visual analog0.60 (0.20)&par;0.62 (0.19)§.51(n = 77)(n = 80)1-Year SF-36 scoresPhysical functioning15.815.6.95Role limitation, physical health36.237.4.84Bodily pain19.417.4.60Social functioning11.66.02.049General health17.813.5.16Role limitation, emotional15.716.4.83Vitality, energy, or fatigue11.512.2.91General health perception6.784.66.40Physical component9.388.71.65Mental component3.252.75.741-Year change from baseline EuroQol 6 scores‡Community weights0.06¶0.074#.66Visual analog0.14**0.15††.63Abbreviations: CABG, coronary artery bypass graft; SF-36, 36-item short form.*One-year SF-36 scores are means that are adjusted for baseline by an analysis of covariance model.†The ttest was used for baseline unpaired data (2-tailed) and analysis of covariance was used to compare changes from baseline at follow-up.‡Community weights are based on utility weights for 5 dimensions of health (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) from a general population in the United Kingdom; visual analog scale is based on a self-rating of current health-related quality of life on a scale of 0 (worst imaginable health state) to 100 (best imaginable health state).§The sample size is 97.&par;The sample size is 96.¶The sample size is 77.#The sample size is 79.**The sample size is 76.††The sample size is 80.CostsThere were 2 patients (both in the OPCAB group) with outlying hospital costs due to severe noncardiac comorbidity (heparin-induced thrombocytopenia and severe Clostridium difficileenterocolitis), which were more than twice the next highest value for the group ($69 883 and $108 353 vs $33 348). Thus, for the primary analysis, hospital costs for these patients were truncated back to the next highest observed value ($33 348). Costs were truncated in the same manner for the patients with the 2 highest observed hospital cost values in the CABG with cardiopulmonary bypass group. Table 6shows results from the overall cost analysis based on truncated data. Mean index hospitalization costs (hospital plus professional costs) were $2272 (95% CI, $755-$3732) lower for the OPCAB group (P= .002). Without truncation of outlying costs, average hospital costs for the index procedure were $18 236 for patients in the CABG with cardiopulmonary bypass group and $17 010 for patients in the OPCAB group (change in cost, $1226 [95% CI, −$1637 to $3575; P= .17). Costs associated with readmission to hospital were similar between groups. The OPCAB treatment remained $1955 (95% CI, −$766 to $4727; P= .08) less expensive on average at 1-year follow-up. Without truncating outlying costs, the difference in 1-year costs was $1266 (95% CI, −$1613 to $3634; P= .16).Table 6.Cost ComparisonOff-Pump Coronary Artery BypassCABG With Cardiopulmonary BypassDifference (95% CI)PValue*(n = 96)(n = 98)Initial hospital cost, mean (SD), US $†Initial cost15 849 (5218)18 080 (4825)2231 (845 to 3625).001Professional cost2947 (1133)2988 (1273)41 (−300 to 385).40Total acute cost18 796 (5552)21 068 (5030)2272 (755 to 3732).002(n = 85)(n = 91)Cumulative hospital costs over 1 y of follow-up, mean (SD), US $‡Initial hospital cost18 618 (4973)20 838 (4879)2220 (751 to 3668).0011-Year follow-up cost4219 (7770)3954 (8334)−265 (−2643 to 2192).59Total 1-year cumulative hospital cost22 837 (9707)24 792 (9140)1955 (−766 to 4727).08Abbreviations: CABG, coronary artery bypass graft; CI, confidence interval.*The bootstrap method was used.†Hospital cost includes all nonprofessional cost categories.‡For all patients with complete 1-year follow-up cost data.COMMENTA preliminary report from the SMART trialdocumented that the mean (SD) number of grafts performed per patient (OPCAB group: 3.39 [1.04]; CABG with cardiopulmonary bypass group: 3.40 [1.08]) and the number of grafts performed per number of grafts intended (index of completeness of revascularization) were similar between groups (OPCAB group: 1.00 [0.18]; CABG with cardiopulmonary bypass group: 1.01 [0.09]). This was the first time that treatment with OPCAB achieved complete revascularization when applied to unselected patients, avoiding the documented negative consequences of incomplete revascularization.Two previous randomized comparisons of OPCAB and CABG with cardiopulmonary bypass have included postoperative angiography. Among low-risk patients, the first study documented angiographic patency among a subset of approximately 25% of enrollees (158 grafts) and reported similar patency rates of 93% for CABG with cardiopulmonary bypass and 91% for OPCAB at 1 year.The second studyreported 3-month angiographic patency rates for 260 grafts among 82 of 103 randomized, low-risk patients. The overall patency rate for grafts performed using conventional CABG was significantly higher than for those performed using OPCAB (98% vs 88%; P= .002). The greatest difference between groups was for patency of radial artery conduits (22/22 [100%] for CABG with cardiopulmonary bypass compared with 26/34 [76%] for OPCAB; P= .01). The 2 surgeons reporting these results had limited experience with OPCAB surgery, having performed only 13% of their isolated coronary bypass procedures off-pump during the preceding 2 years. However, each surgeon was obliged to perform the procedure on each patient in the OPCAB group. Moreover, these surgeons used a relatively low dose of heparin (150 units/kg) in their OPCAB patients and did not supplement that dose intraoperatively.All surgical procedures reported in the present trial were performed by a single experienced OPCAB practitioner, who routinely performs more than 90% of his isolated coronary cases using OPCABand had personal experience in excess of 350 OPCAB cases prior to randomizing patients for this trial. Heparin levels were supplemented at 30-minute intervals. Angiographic results from the SMART trial, obtained in 184 of 197 patients prior to hospital discharge (622 grafts) and 153 of 189 patients at 1 year (511 grafts), demonstrate similar patency and completeness of revascularization in both treatment groups. It is not possible to formally conclude that patency was statistically equivalent between groups; more than 500 patients in each treatment group would have been required to demonstrate such equivalence. Nevertheless, these results suggest that application of OPCAB techniques to unselected patients with multivessel disease need not lead to imprecise anastomoses, nor to a decrement in graft patency.Procoagulant activity may be increased after OPCAB.This phenomenon has been invoked to explain the few isolated reports of diminished vein graft patency after OPCAB.Importantly, patency of saphenous vein grafts was similarly excellent between groups in the present study. Patients in both groups of the SMART trial were treated with perioperative and long-term aspirin; none were prescribed clopidogrel. Nonetheless, awareness of a potential hypercoagulable state among OPCAB patientshas prompted an institutional policy at Emory University since January 2003 of treating OPCAB patients with postoperative clopidogrel for 3 months.Several previous studies have reported improved neuropsychological function after treatment with OPCAB compared with CABG with cardiopulmonary bypass,although this finding has not been uniformly consistent.Results from studies that compared quality-of-life measures after OPCAB and CABG with cardiopulmonary bypass have also been inconsistent.While the weight of peer-reviewed evidence may support the hypothesis that avoidance of cardiopulmonary bypass improves neuropsychological and quality-of-life outcomes after CABG surgery, this important area of investigation remains limited by imprecise assessment toolsand logistical difficulties in performing perioperative testing.Because economic considerations influence medical decision making, the length of stay and cost associated with alternative methods of surgical coronary revascularization are increasingly relevant. With all other acute and long-term outcome measures either similar or superior for the OPCAB group, the decrease in length of stay and cost may influence third-party payers and institutional administrators.The present study has several important limitations. The performance of all surgery by a single surgeon reduced surgical variability, thus making the groups more comparable; but the generalizability of the findings to other surgeons and health care systems has not been proven. No outpatient resource use data was collected during the trial, and thus the evaluation of costs in terms of hospitalization costs alone is limited. However, rehospitalization data capture a large proportion of the costs associated with major adverse events. If OPCAB is associated with lower morbidity compared with CABG with cardiopulmonary bypass, this might be reflected in lower outpatient treatment and medication use for patients receiving OPCAB. Under such circumstances, results based on hospitalization costs alone would yield a conservative estimate of the cost difference between groups.Another important limitation is that 1-year follow-up angiography was only obtained in 78% of the enrolled patients (81% of 1-year survivors). Although there was no systematic difference between the 2 groups regarding lack of 1-year angiography, we cannot exclude the possibility of selection biases affecting our findings. This type of limitation is inherent in trials that require patients to undergo invasive follow-up procedures.These results from the SMART trial demonstrate that OPCAB may provide complete revascularization that is durable and cost-effective relative to CABG with cardiopulmonary bypass when performed on unselected patients undergoing elective, isolated CABG. 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Puskas, MD, MSc, Crawford Long Hospital, Sixth Floor, Medical Office Tower, 550 Peachtree St NE, Atlanta, GA 30308 (john_puskas@emoryhealthcare.org).Author Contributions:Dr Puskas had full access to all of the data in the study and takes full responsibility for the integrity of the data and for the accuracy of the data analysis.Study concept and design:Puskas, Williams, Duke, Marshall, Petersen, Weintraub, Guyton.Acquisition of data:Williams, Huber, Block, Duke, Staples, Marshall, Leimbach, McCall, Bailey.Analysis and interpretation of data:Puskas, Williams, Mahoney, Huber, Block, Glas, Marshall, Leimbach, Weintraub.Drafting of the manuscript:Puskas, Williams, Duke, Marshall, McCall, Petersen, Weintraub.Critical revision of the manuscript for important intellectual content:Puskas, Williams, Mahoney, Huber, Block, Duke, Staples, Glas, Leimbach, Bailey, Weintraub, Guyton.Statistical expertise:Williams, Mahoney, Weintraub.Obtained funding:Puskas, Petersen, Guyton.Administrative, technical, or material support:Williams, Huber, Block, Duke, Marshall, Leimbach, McCall, Petersen, Bailey, Weintraub, Guyton.Supervision:Puskas, Williams, Mahoney, Block, Duke, Staples, Guyton.Funding/Support:The research for this article was supported by grants from Medtronic Inc and the Carlyle Fraser Heart Center Foundation (Atlanta, Ga).Role of the Sponsors:The study sponsors played no role in the design, methods, data management or analysis, nor in the decision to publish.

Journal

JAMAAmerican Medical Association

Published: Apr 21, 2004

References