Background: Myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) is a heterogeneous entity often overlooked in contemporary medicine. We aim to determine MINOCA differential characteristics, the main etiologies, and prognostic outcomes.
Patients and methods: We carried out a retrospective longitudinal analysis including 1047 patients with MI, from 1 January 2011 to 1 January 2016, subjected to coronary angiography and classified according to the presence [MI and obstructive coronary artery disease (MICAD)] or absence (MINOCA) of any coronary stenosis of at least 50%. Studied data included clinical, demographic, laboratorial, and angiographic features. The median follow-up duration was 35 (interquartile range: 25) months. Mortality was the primary endpoint. To identify MINOCA underlying etiologies, only the final diagnosis obtained according to the European Society of Cardiology proposed algorithm was accepted. To determine MINOCA predictors, multivariate analysis with logistic regression was carried out.
Results: The mean age of the patients was 66.3±13.4 years; 319 (30.5%) patients were women. The MINOCA group included 114 (10.8%) patients. The underlying final diagnosis in the MINOCA group was obtained in 78 (68.4%) patients. The total mortality rate was 8.8% (n=10) in the MINOCA group versus 17.7% (n=165) in the MICAD group, P=0.018. After multivariate analysis, age [odds ratio (OR)=1.05, 95% confidence interval (CI): 1.03-1.07, P<0.001], female sex (OR=3.91, 95% CI: 2.53-6.06, P<0.001), no previous tobacco use (OR=3.41, 95% CI: 1.68-3.90, P=0.001), atrial fibrillation (OR=3.62, 95% CI: 1.56-8.40, P=0.003), no previous AMI (OR=6.85, 95% CI: 1.65-28.5, P=0.008), and non-ST-segment elevation myocardial infarction diagnosis (OR=5.36, 95% CI: 2.62-10.96, P<0.001) remained independent predictors of MINOCA.
Conclusion: MINOCA represents a challenging group of heterogeneous patients whose clinical characteristics contrast with classical cardiovascular risk factors. Despite lower mortality than MICAD, the commonly attributed low-risk classification for MINOCA may be erroneous.