RISK ANALYSIS OF CORONARY-BYPASS SURGERY AFTER ACUTE MYOCARDIAL-INFARCTION

Background. Current strategies for management of acute myocardial infa rction (MT) include thrombolysis, angioplasty, and coronary bypass sur gery singly or in combination. This study was designed to identify con temporary risk factors for coronary bypass surgery among patients in t his high-risk group. Methods. Between June 1992 and December 1995, 118 1 consecutive patients underwent isolated coronary bypass surgery. Of these, 316 underwent coronary bypass surgery within 21 days of MI. Mea n age was 65 years (range, 33 to 87 years), and 73% were male. There w ere 166 patients with stable angina (group 1), 107 patients with unsta ble angina requiring intravenous nitroglycerin for a control of ischem ia (group 2), 20 patients with angina requiring intraaortic balloon co unterpulsation for stabilization (group 3), and 23 patients with sever e 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 u ndergoing coronary bypass surgery without recent myocardial infarction . Mortality increased with severity of clinical preoperative status an d was 1.2% in group 1, 3.7% in group 2, 20.0% in group 3, and 26% in g roup 4. Serious postoperative morbidity occurred in 7.3% of patients. Multivariate logistic regression analysis identified preoperative intr aaortic balloon counterpulsation, left ventricular dysfunction, and re nal insufficiency as the only independent correlates of mortality. Con clusions. Coronary bypass surgery can be safely performed in stable pa tients at any time after acute MI, with an operative mortality similar to elective surgery. Thus, in this era of medical cost containment, t here is no apparent indication for prolong ed stabilization attempts t hat delay surgery.