Effect of continued rt-PA administration on the residual stenosis after initially successful recanalization in acute myocardial infarction - a quantitative coronary angiography study of a randomized trial

Quantitative angiography was performed in 68 out of 123 patientstreated with intravenous rt-PA for acute myocardial infarction.At 90 min angiography, the median minimal cross-sectional areawas 1.11 mm² and the median percentage area stenosis was 80%.A percentage area stenosis greater than 70% was seen in 78%of the patients. Patients with a patent infarct related artery at the first angiogramwere randomized to receive subsequent infusions either of rt-PA+ heparin or placebo + heparin. There was a persistent trendof improvement in minimal lumen diameter and percentage diameterstenosis of the residual stenosis in the infarct related arteryin both treatment groups when re-examined 6–24 hours laterand at the time of hospital discharge. A reduction in ‘plaquearea’, the area between the detected and the referencecontours of the infarct related segment, was more frequentlyseen in patients receiving a second infusion of rt-PA than inpatients with no prolonged thrombolytic therapy (83% versus57%, P<0.025, chi square).