Clinical trials of revascularization therapy in diabetics

Abstract

Diabetic patients are a high-risk group for cardiovascular morbidity and mortality, with poorer long-term outcomes, with or without revascularization, than non-diabetic patients. Results from the Bypass Angioplasty Revascularization Investigation (BARI) trial, the largest randomized study of coronary revascularization strategies, showed that diabetic patients with multivessel coronary disease who were undergoing an initial revascularization procedure had a significant long-term survival advantage with coronary artery bypass graft surgery (CABG) compared with percutaneous transluminal coronary angioplasty (PTCA). The 8-year follow-up data from the Emory Angioplasty Versus Surgery Trial (EAST) study, the other major US trial of CABG versus PTCA, and results of other clinical trials that enrolled similar patients are consistent with an advantage for CABG in diabetic patients but not for nondiabetic patients. This benefit is entirely a result of improved cardiac mortality. It is limited to patients receiving an internal mammary artery (IMA) graft and is apparent earlier in insulin-treated patients. The benefit of CABG in diabetic patients may be significantly related to a protective effect on mortality after myocardial infarction, because CABG greatly reduced the risk of death after spontaneous Q-wave myocardial infarction in BARI-eligible diabetic patients (relative risk 0.09, P<0.001), an effect not seen in non-diabetic patients.