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 patients treated with intravenous rt-PA for acute myocardial infarction. At 90 min angiography, the median minimal cross-sectional area was 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 patient infarct related artery at the first angiogram were randomized to receive subsequent infusions either of rt-PA + heparin or placebo + heparin. There was a persistent trend of improvement in minimal lumen diameter and percentage diameter stenosis of the residual stenosis in the infarct related artery in both treatment groups when re-examined 6-24 hours later and at the time of hospital discharge. A reduction in 'plaque area', the area between the detected and the reference contours of the infarct related segment, was more frequently seen in patients receiving a second infusion of rt-PA than in patients with no prolonged thrombolytic therapy (83% versus 57%, P less than 0.025, chi square).