Assess the efficacy of a thrombolytic agent in reducing infarct size and thereby improving ventricular function and subsequent morbidity and mortality. The primary endpoint will be total mortality during the follow up period. Secondary endpoints include determination of the: effect of thrombolytic therapy on left ventricular ejection fraction;proportion of patients suspected of having myocardial infarction with complete versus incomplete occlusion of the infarct related artery; time limits for successful reperfusion including differences according to the route of administration; and frequency and severity of adverse effects of intracoronary and intravenous administration of thrombolytic agents in patients with acute infarction.