A short overview summarizing two significant studies from the United States on rt-PA

Abstract

The first prospective, randomized, placebo controlled trial of intravenous recombinant human tissue-type plasminogen activator (rt-PA) was published in 1984 (1). 45 patients (35 male, 10 female) with acute transmural myocardial and angiographically-confirmed complete coronary occlusion were prospectively randomized, two to one, in the treatment of acute coronary thrombosis with intravenous rt-PA or placebo. Interval from onset of pain to randomization was 284 ± 99 minutes (mean ± SD). Each of 5 additional, consecutive patients was treated with a high dose of rt-PA for two hours. 25 of 33 patients (75%) receiving 0.5 to 0.75 mg/kg body weight of rt-PA over 30 to 120 minutes had angiographically proven recanalization within 90 minutes of initation of therapy (Table 1). Only one of 14 patients given placebo had spontaneous recanalization within 45 min (p< 0.001). 13 placebo treated patients were changed over to intracoronary rt-PA treatment (0.375 mg/kg body weight). 9 (69%) exhibited subsequent recanalization within 45 minutes. The level of circulated fibrinogen decreased by only 8% of baseline value after treatment with rt-PA. None of the patients treated with rt-PA manifested a depletion in the fibrinogen level to below 100 mg/dl.