Myocardial ischemic syndromes account for a large portion of the annual mortality and morbidity from all causes in industrialized countries and encompass a wide clinical-pathologic spectrum. At one end of this spectrum are patients with chronic stable angina. When studied by coronary arteriography, such patients usually have obstructive atherosclerotic disease with no evidence of fresh thrombosis. At the other end of the spectrum are patients with acute myocardial infarction who present with a discrete episode of prolonged chest pain accompanied by persistent ST-segment elevation. Such patients have a high incidence of thrombotic coronary artery occlusion and the early intravenous administration of thrombolytic agents has been shown to re-establish perfusion, limit the extent of left ventricular dysfunction, and reduce both early or in-hospital and late or one year mortality in this group.