Coronary bypass graft patency in patients with diabetes in the bypass angioplasty revascularization investigation (BARI)

Percutaneous Coronary Intervention vs. Coronary Bypass Graft Surgery for Diabetic Patients With Unstable Angina and Risk Factors for Adverse Outcomes With Bypass. Outcome of Diabetic Patients in the AWESOME Randomized Trial and Registry

long-term adjunctive dual antiplatelet therapy should continue to improve outcomes in diabetic patients undergoing PCI. DM

Coronary Bypass Graft Patency in Patients With Diabetes in the Bypass Angioplasty Revascularization Investigation (BARI)

Sedlis SP, Morrison DA, Lorin JD, et al., and Investigators of the Department of Veterans Affairs Cooperative Study #385, the Angina With Extremely Serious Operative Mortality Evaluation (AWESOME). J Am Coll Cardiol 2003;40:1555– 66.

Schwartz L, Kip KE, Frye RL, Alderman EL, Schaff HV, Detre KM. Circulation 2002;106:2652– 8.

Study Question: The authors compared survival after percutaneous coronary intervention (PCI) with survival after coronary artery bypass graft surgery (CABG) among diabetics in the Veterans Affairs AWESOME (Angina With Extremely Serious Operative Mortality Evaluation) study randomized trial and registry of high-risk patients. Methods: AWESOME was a nationwide prospective randomized clinical trial designed to compare CABG and PCI survival for patients with medically refractory unstable angina and at high risk of adverse outcomes with CABG. A post-hoc subgroup analysis of the diabetic patients was performed. Over 5 years, 2431 patients with medically refractory myocardial ischemia and at least one of five risk factors (prior CABG, myocardial infarction within 7 days, left ventricular ejection fraction ⬍0.35, age ⬎70 years or an intra-aortic balloon being required to stabilize) were identified. A total of 781 were acceptable for CABG and PCI, and 454 consented to be randomized. The 1650 patients not acceptable for both CABG and PCI constitute the physiciandirected registry, and the 327 who were acceptable but refused to be randomized constitute the patient-choice registry. Diabetes prevalence was 32% (144) among randomized patients, 27% (89) in the patient-choice registry and 32% (525) in the physician-directed registry. The CABG and PCI survival rates were compared using KaplanMeier curves and log-rank tests. Results: The respective 36-month survival rates for diabetic patients were 72% with CABG and 81% with PCI for randomized patients, 85% with CABG and 89% with PCI for patient-choice registry patients and 73% with CABG and 71% with PCI for the physician-directed registry patients. None of the differences was statistically significant by log rank test. Conclusions: The authors concluded that PCI is a relatively safe alternative to CABG for diabetic patients with medically refractory unstable angina who are at high risk for CABG. Perspective: This contemporary study using stents and adjunctive glycoprotein IIb/IIIa inhibitors demonstrated that there is no survival advantage with CABG compared to PCI in high-risk diabetic patients with unstable angina and risk factors for adverse outcomes. The small sample size in each group may have underpowered the analysis to detect small differences but survival appears marginally better with PCI in these high-risk patients. Recent advances in interventional technology such as drug-coated stents and

Study Question: What are the differences in the long-term status of coronary artery bypass grafts (CABG) between patients with and without diabetes? Methods: Among patients enrolled in BARI who underwent CABG as initial revascularization (n⫽1526), 292 had treated diabetes mellitus (TDM) (those on insulin or oral hypoglycemic agents) and 1234 were without TDM. Follow-up angiography was performed in 99 and 469 of patients with and without TDM, respectively. Angiograms with the longest interval from initial surgery and before any percutaneous graft intervention (mean 3.9 years) were reviewed. Results: At initial CABG, the average number of grafts (3.0 vs. 2.9) and internal mammary artery grafts (33% vs. 34%) utilized were similar for patients with and without TDM, respectively. Patients with TDM were more likely than those without to have small (⬍1.5 mm) grafted distal vessels (29% vs. 22%, p⬍0.0001) and vessels of poor quality (9% vs. 6%, p⬍0.0001). On follow-up angiography, the proportion of IMA grafts free of stenoses (ⱖ50%) (89% vs. 85%, p⫽0.23) and the proportion of vein grafts free of stenosis (71% vs. 75%, p⫽0.40) were similar among patients with TDM and those without TDM. TDM was found to be unrelated to having a graft stenosis ⬎50% on follow-up coronary angiograms (adjusted odds ratio, 0.87; 95% CI, 0.58 –1.32). Conclusions: Diabetes does not appear to adversely affect patency of IMA or vein grafts over an average of 4-year follow-up and thus does not account for the previously observed differences in survival between CABG-treated patients with and without diabetes, which may be largely a result of differential risk of mortality from noncardiac causes. Perspective: The potential biases inherent in the current study are multiple. First, angiographic follow-up was not available in patients dead at 1 year or at 5 years (but rather available only on patients that survive at this time point). Second, non-protocol driven coronary angiography in more than two thirds of the patients may confound the findings of this study. The conclusion that diabetes is associated with no incremental risk of stenosis of bypass grafts of patients undergoing CABG needs to be interpreted in light of these biases. RM

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