Abstract
Intravenous administrations of 2000×104IU (33mg) (rt-PA2) and 3000×104IU (50 mg) (rt-PA3) of a new recombinant tissue plasminogen activator (rt-PA : TD-2061) derived from uterine endotherial cells and urokinase (UK) 96×104IU were compared in a double blind, randomized trial of 198 patients with evolving myocardial infarction. All patients entered the trial within 6 h of the onset of symptoms and underwent baseline coronary angiography of the infarct-related coronary artery before thrombolytic therapy was instituted. Sixty minutes following thrombolytic therapy occluded infarct-related arteries were successfully reperfused in 41.5% of 66 patients in the UK, 76.4% of 72 patients in the rt-PA2, and 74.6% of 59 patients in the rt-PA3 group. Statistically significant differences were observed between the UK and rt-PA groups (p<0.01). Serum fibrinogen levels declined in all 3 groups at 60 min post-therapy by averages of 35.9±3.1% in the UK, 16.8±4.8% in the rt-PA2 and 17.5±4.5% in the rt-PA3 group. The difference between the UK and the rt-PA groups was statistically significant (p<0.01). Plasma plasminogen and α2-plasmin inhibitor levels showed the same tendencies. Bleeding was the most commonly observed complication and was most commonly seen at the catheterization site. There was no difference in the incidence among the 3 groups. Hospital deaths occurred in 5.3%, 6.3%, and 4.7% of the cases in the UK, rt-PA2 and rt-PA3 groups, respectively. We conclude, therefore, that rt-PA achieves a significantly higher rate of recanalization with less extensive systemic fibrinogenolysis at the dose employed than does UK. The optimum intravenous dose of rt-PA for Japanese patients is considered to be 2000×104IU (33mg).
