Determining whether acute myocardial infarction in patients with previous coronary bypass grafting is the result of narrowing of a bypass conduit or of a native coronary artery.

The relation between electrocardiographic changes and the infarct-related coronary artery was studied in 76 patients with acute myocardial infarction 77 +/- 49 months after coronary artery bypass surgery in a retrospective series. When the infarct-related coronary artery was a graft, the electrocardiogram showed ST elevation and new Q waves less often; although the infarction was smaller, these patients presented a worse in-hospital prognosis.