Mortality, mode of death and risk indicators for death during 5 years after coronary artery bypass grafting among patients with and without a history of diabetes mellitus

OBJECTIVE: To describe mortality, mode of death, risk indicators for death and symptoms of angina pectoris among survivors during 5 years after coronary artery bypass grafting (CABG) among patients with and without a history of diabetes mellitus. METHODS: All patients in western Sweden who underwent CABG without concomitant valve surgery and who had no previous CABG between June 1988 and June 1991 were entered prospectively in this study. After 5 years, information on deaths that had occurred was obtained for the analysis. RESULTS: In all, 1998 patients were included in the analysis; 242 (12%) had a history of diabetes. Among the non-diabetic patients, 5-year mortality was 12.5%; the corresponding relative risk for diabetic patients was 2.1 (95% confidence interval 1.6 to 2.9). A history of diabetes was an independent risk indicator of death; there was no significant interaction between any other risk indicator and diabetes. Independent risk indicators for death among diabetic patients were: current smoking, renal dysfunction and left ventricular ejection fraction < 0.40. Compared with non-diabetic patients, those with diabetes more frequently died in hospital, died a cardiac death, or had death associated with the development of acute myocardial infarction and with symptoms of congestive heart failure. Among survivors, diabetic patients tended to have more angina pectoris 5 years after CABG than did those without diabetes. CONCLUSION: During a period of 5 years after CABG, diabetic patients had a mortality twice that of non-diabetic patients. The increased risk included death in hospital, cardiac death and death associated with development of acute myocardial infarction and with symptoms of congestive heart failure.