OPTIMAL TIMING OF CORONARY-ARTERY BYPASS GRAFT-SURGERY AFTER ACUTE MYOCARDIAL-INFARCTION

Background To assess optimal timing for coronary artery bypass graft s urgery (CABG) after an acute myocardial infarction (AMI), all patients undergoing CABG without associated procedures at our institution from January 1, 1991, to July 30, 1992, were reviewed. Patients were divid ed into three groups based on time from infarct to revascularization. The control group consisted of patients operated on for angina refract ory to medical management. Relative risks (incident infarction group d ivided by incident control group) were established for need of vasopre ssors, new balloon to separate from bypass, perioperative myocardial i nfarction, and hospital mortality. Methods and Results One hundred six teen patients underwent CABG within 6 weeks of infarction. In the expe rimental group, 58 patients underwent CABG for non-Q-wave infarction, and 58 patients underwent CABG for Q-wave infarction. In the control g roup, 255 patients underwent surgery for angina without infarction. Pa tients were analyzed by group relative to the time between infarction and CABG. Patients were analyzed between infarction and CABG and assig ned to one of three groups. Group 1 patients were revascularized withi n 48 hours; group 2, between 3 and 5 days; and group 3, after 5 days. Significance was determined by Fisher's exact or Mantel-Kaenszel chi(2 ) test where appropriate. Multivariate analysis was performed on stati stics that were significant. All patients within all groups after Q-wa ve or non-Q-wave myocardial infarction had a significantly higher risk of needing an intra-aortic balloon pump and vasopressors to be weaned from bypass and a greater incidence of perioperative MI compared with control patients. Surgical mortality is highest immediately after Q-w ave infarctions. Conclusions Patients with non-Q-wave infarction may u ndergo CABG relatively safely at any time. Acceptable timing for CABG after Q-wave infarction is after 48 hours.