Reduction of infarct size estimated enzymatically in patients with acute myocardial infarction after treatment with recombinant tissue type plasminogen activator or after spontaneous coronary recanalisation: A randomised, placebo controlled study

Abstract

In a double-blind trial, 56 patients with suspected myocardial infarction (AMI) of a duration of less than 5 h were randomised to either 100 mg recombinant human tissue type plasminogen activator (rt PA) treatment or placebo intravenously over 3 h. We studied the possible influence of endogenous coronary recanalisation on the extent of myocardial damage in relation to the estimate of myocardial salvage by early treatment of AMI patients with rt PA. We used a computerised serum CK MB time activity curve method for estimation of reperfusion and infarct size. Patients with a first AMI had a significantly higher reperfusion rate than patients with a previous AMI (p=0.01). In the placebo group, the median enzymatic estimated infarct size was significantly lower in the patients with spontaneous reperfusion compared to patients with no endogenous reperfusion (p < 0.05). The median infarct size was significantly lower (33%) in patients treated with rt PA than in patients without spontaneous reperfusion (p < 0.05). We conclude that rt PA is efficient in inducing coronary reperfusion in the majority of patients with a first AMI. Our results confirm that intravenously, administered rt PA treatment can reduce the infarct size in patients with AMI. Our study extends previous observations by indicating that the extent of myocardial salvage induced by such treatment has been underestimated in the past, where patients with spontaneous coronary reperfusion have been included in the reference group.