CAUSE OF ACUTE MYOCARDIAL-INFARCTION LATE AFTER SUCCESSFUL CORONARY-ARTERY BYPASS-GRAFTING

Coronary artery bypass grafting (CABG) reduces angina and improves exercise tolerance in patients with symptomatic coronary artery disease. Further, it improves survival in selected high-risk patients. Despite these dramatic results CABG has not been shown to reduce the incidence of acute myocardial infarction (AMI). In each of 3 large randomized CABG trials the frequency of nonfatal AMI was not reduced.1-3. The causes of AMI occurring months or years after successful CABG have not been well defined. In patients who have undergone CABG, AMI may potentially result from occlusion of a graft to an artery that has already closed, occlusion of an artery whose graft has previously closed or occlusion of an ungrafted native coronary artery.4 Recently, we observed that AMI in medically treated patients with coronary artery disease frequently was due to occlusion of an artery that previously did not contain an obstruction.5 This suggests that occlusion of unbypassed arteries that did not previously contain obstructions may be an important cause of AMI after CABG. © 1990.