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 follow-up (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.