Influence of Diabetes on 5-Year Mortality and Morbidity in a Randomized Trial Comparing CABG and PTCA in Patients With Multivessel Disease

Abstract

Background Patients with diabetes mellitus have increased morbidity and mortality after coronary revascularization. The Bypass Angioplasty Revascularization Investigation (BARI), a trial of percutaneous transluminal coronary angioplasty (PTCA) versus coronary artery bypass graft surgery (CABG) in patients with multivessel disease, reported a 5-year survival advantage of CABG over PTCA in patients with treated diabetes mellitus (TDM). This report examines these findings in more detail. Methods and Results Eighteen clinical centers randomly assigned 1829 patients with multivessel coronary disease to undergo initial CABG or PTCA. Patients were followed an average of 5.4 years. TDM was defined as a history of diabetes with use of oral hypoglycemic agents or insulin at study entry. Nineteen percent of the randomized population (353 patients) met these criteria. TDM patients had more unfavorable baseline characteristics than other patients, but among TDM patients, these characteristics were similar between the CABG and PTCA groups. Better average 5.4-year survival with CABG was due to reduced cardiac mortality (5.8% versus 20.6%, P =.0003), which was confined to those receiving at least one internal mammary artery graft. Conclusions Patients with TDM assigned to an initial strategy of CABG have a striking reduction in cardiac mortality compared with PTCA. Long-term internal mammary artery graft patency may contribute to this improved outcome by reducing the fatality of follow-up myocardial infarction.