Mortality and myocardial infarction after coronary artery surgery

OBJECTIVE: To review the results of uncomplicated coronary artery bypass graft surgery and to identify factors which influence operative mortality (OM) and postoperative myocardial infarction (PMI). DESIGN: An analysis of the outcome in patients having coronary artery bypass graft surgery for the first time from 1978 to 1990 inclusive. SETTING: The Cardiothoracic Surgery Unit at the Royal Adelaide Hospital. PARTICIPANTS: Twelve thousand and twenty-two patients had coronary artery bypass graft surgery only. Complete data were available for 12,003 patients. RESULTS: There was an overall mortality rate of 0.99% and a postoperative myocardial infarction rate of 1.34%. Older patients and women had a higher operative mortality rate. Both unstable angina and poor ventricular function increased the mortality rate. The only significant operative factor was the perfusion time. There was a more than 16-fold increase in mortality in patients who had an average bypass time (48 minutes) compared with those whose bypass time was 100 minutes or more (0.63% v. 10.3%). The PMI rate changed over the study period, and was also influenced by the presence of unstable angina and the duration of bypass: unstable angina doubled the rate from 0.86% to 1.91%, and with an average bypass time the PMI rate was 0.56% whereas with a bypass time of 100 minutes or more the rate increased to 7.7%. CONCLUSIONS: The outcome after coronary artery bypass graft surgery is strongly dependent on the perfusion time and the presence of unstable angina. Older patients and women are more likely to die during the operation.