High-dose, brief intravenous streptokinase early in acute myocardial infarction.

An acute thrombus at the proximal border of a high-grade atherosclerotic obstruction is the usual cause of myocardial infarction. Although intracoronary thrombolysis is potentially an exciting new therapy for reducing the extent of myocardial infarction by lysing coronary clot, a number of major difficulties limit its widespread application. It is a complex procedure requiring intracoronary visualization and infusion within a few hours of onset of symptoms. Since intravenous streptokinase could be widely applied if effective, we and others have wondered whether high-dose, brief-duration intravenous streptokinase infusion given early in myocardial infarction would lyse coronary clots without bleeding. To date we have treated 13 patients within 6 hours of onset of symptoms and with ECG and angiographic evidence of typical myocardial infarction caused by coronary clot. Clot lysis and angiographically proved coronary reperfusion were achieved in 6 patients within 1 hour of starting a systemic intravenous infusion of 850,000 IU of streptokinase. Schroeder et al., in Berlin, West Germany, achieved angiographically proved coronary reperfusion in 11 of 21 patients with acute myocardial infarction following a 30-minute intravenous streptokinase infusion of 500,000 IU. Neuhaus et al., in Göttinen, West Germany, achieved angiographically proved coronary reperfusion in 24 of 39 similar patients within 48 minutes by intravenous infusion of 1,700,000 IU of streptokinase. In these three studies, no serious bleeding occured; left ventricular function was improved in patients who achieved coronary reperfusion. We conclude that rapid intracoronary clot lysis and coronary reperfusion can be achieved early in myocardial infarction by brief-duration systemic intravenous infusion of high-dose streptokinase without a high incidence of serious bleeding.