Long-Term Survival after CABG in Diabetics with Aggressive Risk Factor Management

Objectives: Diabetes is a well-established risk factor for cardiovascular disease, and diabetics have a threefold increase in risk of death from cardiovascular disease compared to non-diabetics. Following coronary artery bypass grafting, tight glycemic control improves short-term outcomes, however limited data exist for long-term outcomes. Here we examine these outcomes in diabetics using aggressive risk factor management. Methods: A retrospective review of all patients under-going coronary artery bypass between 1991 and 2000 at a single Veterans Affairs Medical Center was undertaken. 973 patients were included, 313 with diabetes and 660 without. Strict glucose control was maintained for all patients. Additional risk factor modification, including anti-platelets medications, statins, and beta blockers were also used. Survival analysis was performed. Results: The diabetic group was at higher risk, with age, BSA, and NYHA class all being greater (p < 0.05). The mean follow-up time was 6.7 ± 3 years. There were 28 deaths/1000 person-years for non-diabetics, and 48 deaths/1000 person-years for diabetics. Survival rates were significantly higher for non-diabetics (72% versus 58% in the diabetic group, p < 0.001). Cox proportional hazard analysis demonstrated mortality risk was 57% higher for diabetic patients (hazard ratio = 1.57; CI: 1.19 - 2.09; p = 0.002). The mortality risk in diabetics with and without prior MI was similar (HR = 0.83; CI: 0.54 - 1.28; p = 0.40). Conclusions: Diabetics undergoing coronary bypass have poorer long-term survival than non-diabetics despite perioperative glycemic control and risk factor modification. The long-term survival decrease in diabetics with history of MI is attenuated with surgical revascularization.