Risk analysis of coronary bypass surgery after acute myocardial infarction

Background. Current strategies for management of acute myocardial infarction (MT) include thrombolysis, angioplasty, and coronary bypass surgery singly or in combination. This study was designed to identify contemporary risk factors for coronary bypass surgery among patients in this high-risk group. Methods. Between June 1992 and December 1995, 1181 consecutive patients underwent isolated coronary bypass surgery. Of these, 316 underwent coronary bypass surgery within 21 days of MI. Mean age was 65 years (range, 33 to 87 years), and 73% were male. There were 166 patients with stable angina (group 1), 107 patients with unstable angina requiring intravenous nitroglycerin for a control of ischemia (group 2), 20 patients with angina requiring intraaortic balloon counterpulsation for stabilization (group 3), and 23 patients with severe postinfarction ischemia complicated by cardiogenic shock (group 4). Results. The overall in-hospital mortality rate was 5.1% (16 of 316), which was higher (p < 0.05) than the 2.5% (22 of 865) among patients undergoing coronary bypass surgery without recent myocardial infarction. Mortality increased with severity of clinical preoperative status and was 1.2% in group 1, 3.7% in group 2, 20.0% in group 3, and 26% in group 4. Serious postoperative morbidity occurred in 7.3% of patients. Multivariate logistic regression analysis identified preoperative intraaortic balloon counterpulsation, left ventricular dysfunction, and renal insufficiency as the only independent correlates of mortality. Conclusions. Coronary bypass surgery can be safely performed in stable patients at any time after acute MI, with an operative mortality similar to elective surgery. Thus, in this era of medical cost containment, there is no apparent indication for prolong ed stabilization attempts that delay surgery.