Coronary thrombolysis and myocardial salvage by tissue plasminogen activator given up to 4 hours after onset of myocardial infarction. National Heart Foundation of Australia Coronary Thrombolysis Group

Abstract

144 patients presenting within 4 h of onset of myocardial infarction were randomised to receive either 100 mg of single-strand recombinant tissue plasminogen activator (rTPA) in 3 h (n = 73) or placebo infused at the same rate (n = 71). All patients were given heparin 5000 units before the infusion and heparin was continued, initially at 1000 units per hour, after the infusion. Minor bleeding was more frequent in the rTPA recipients, and during subsequent anticoagulant therapy there were three clinically significant bleeding episodes in this group. Patency of the infarct-related coronary artery was determined by coronary angiography about one week post-infarction, 125 angiograms being assessable. The infarct-related artery was patent in 70% of patients who received rTPA and in 41% of those who did not (p = 0.0015). In the 103 patients who had assessable contrast ventriculograms, the global ejection fractions were 57.7% and 51.7%, respectively (p = 0.04). The difference in ventricular function was largest in patients with anterior infarction (52.7% versus 40.0%, p = 0.02). The magnitude of these changes suggests an improvement in ejection fraction of 12% overall and about 30% in patients with anterior infarction.