Non-ST-Elevation Acute Myocardial Infarction With Normal Coronary Arteries: Predictors and Prognosis

Introduction and objectives. Occasionally, coronary arteries without significant stenosis are observed during invasive treatment of acute non-ST-elevation myocardial infarction (NSTEMI). The aim was to investigate predictive factors and prognosis in these patients. Methods. The study involved 504 patients admitted for NSTEMI who underwent cardiac catheterization. The primary end-point was the observation of coronary arteries without significant stenosis, and the secondary end-point was death or myocardial infarction within a median of 3 years. In evaluating the secondary end-point, a control group of 160 patients with a normal troponin level and no significant coronary artery stenosis who were admitted for chest pain during the same period was included. Results. Overall, 64 patients (13%) had coronary arteries without significant lesions. The predictors were: female sex (odds ratio [OR]=6.6; P=.0001), age <55 years (OR=3.0; P=.001), and the absence of diabetes (OR=2.4, P=.02), previous antiplatelet treatment (OR=3.9, P=.007) or ST-segment depression (OR=2.4, P=.008). The composite variable of female sex plus at least two additional predictive factors had a specificity of 85% and a sensitivity of 53% for coronary angiography showing no significant stenosis. The absence of coronary artery stenosis decreased the probability of death or myocardial infarction during followup (hazard ratio=0.3, 95% confidence interval, 0.2-0.9; P=.03). Among all patients without significant stenosis (n=224), there was no difference in the event rate between those with elevated and normal troponin levels. Conclusions. In NSTEMI, female sex, age <55 years and the absence of diabetes, previous antiplatelet treatment or ST-segment depression were all associated with coronary angiography showing no significant stenosis. The long-term prognosis in these patients was good.