Irregular coronary lesion morphology after thrombolysis predicts early clinical instability

After successful thrombolytic treatment for acute myocardial infarction, recurrent ischemia and infarction may occur with little warning. Coronary lesion morphology was analyzed from angiograms performed in 72 consecutive patients at 1 to 8 days after streptokinase treatment for acute myocardial infarction and the data were evaluated in relation to the subsequent clinical course. All patients were clinically stable at the time of angiography and continued to receive heparin infusion for ≥4 days after thrombolysis. The infarct-related artery was patent in 55 patients (76%). In the 10 days after angiography, 15 patients developed prolonged episodes of angina at rest; the condition of 4 stabilized with medical treatment, but 11 required urgent medical intervention (coronary angioplasty in 8 and bypass surgery in 3). There were no differences in age, gender, left ventricular function or extent of coronary artery disease between those patients who developed unstable angina and those who had a stable in-hospital course. However, the median plaque ulceration index of the infarct-related lesion was 6.7 (95% confidence limits 6.3, 10) in the 15 patients with an unstable course versus 3.3 (2, 4.4) in those with a stable course (p < 0.001). There were no differences between the two patient groups in the severity of stenosis, length of diseased segment, symmetry/eccentricity, presence of a shoulder, location at branch point or bend, presence of globular or linear filling defects, contrast staining or collateral supply. These data show that after thrombolysis, the degree of irregularity of the infarct-related artery is a critical determinant of early clinical instability. Of the 19 patients with a plaque ulceration index >6, 11 (58%) subsequently demonstrated clinical instability compared with only 4 (8%) of the 53 patients with an ulceration index