A comparative study on the effects of low dose of tPA and different regimens of intravenous urokinase in acute myocardial infarction.

OBJECTIVE:To compare the effects of low dose of recombinant tissue-type plasminogen activator (tPA) with those of conventional dose of urokinase (UK) and assess the influence of different regimens of intravenous UK in patients with acute myocardial infarction (AMI). METHODS:Eighty patients with AMI were randomized to 50 mg of tPA (Group I; n = 26) using an accelerating approach or 1.0-1.5 million U of UK (Group II; n = 54). UK was administered as a single bolus injection of whole dose (Group IIa; n = 26) or half dose bolus injection followed by half dose infusion (Group IIb; n = 28). All patients underwent coronary arteriography 90 min after the initiation of intravenous thrombolysis, and the infarct-related coronary artery (IRA) patency was evaluated. Cardiac events during hospitalization were recorded and predischarge left ventricular function was determined by two-dimensional echocardiography. RESULTS:The IRA patency rate was significantly higher in Group I (88.4%) than in Group II (53.7%) (P < 0.01). Group I patients had less cardiac events during hospitalization (11.5% vs 33.3%) and greater improvement in left ventricular function than Group II patients. However, these angiographic, left ventricular functional and prognostic parameters did not significantly differ between Group IIa and Group IIb. CONCLUSIONS:Thrombolysis after AMI with low dose of intravenous tPA exerts better angiographic and clinical effects than that with conventional dose of UK. The thrombolytic effects of UK were not affected by different regimens of intravenous administration of the agent.