Abstract

Objective To assess the characteristics and prognosis of patients with myocardial infarction and non-obstructed coronary arteries (MINOCA). Methods MINOCA was defined as acute myocardial infarction (AMI) with angiographic coronary stenosis <50%.Cardiomyopathies and myocarditis were — a priori — excluded from the study. Stenoses <30% were considered normal coronary arteries (NCA); stenoses ≥30% but <50% were considered mild coronary artery disease (MCAD). Patients were subdivided in 3 groups: I) NCA (0 vessels; stenosis <30%); II) 1–2 vessels showing MCAD and III) MCAD in 3 vessels or the left main stem (LMS). Results From January 2006 to December 2014, 7935 consecutive AMI patients were entered into our institutional database;150 (2%) were diagnosed as having MINOCA. At a median follow-up of 7.1 years the composite end-point (cardiovascular death, AMI or acute coronary syndrome, heart failure, stroke) occurred in 23 patients (17.4%). Survival analysis showed no differences between NCA versus MCAD (p = 0.781). When assessed by distribution of CAD, group III had a lower event-free survival compared to group I and group II, respectively 54 ± 14%, 83 ± 4% and 90 ± 5% (p = 0.001). In a multivariate model, only 3 vessel disease or LMS involvement (HR = 23.5, 95% CI 2.59–173.49, P = 0.001) and high C-reactive protein at hospital admission (HR = 1.47, 95% CI 1.06–2.07, P = 0.005) were significant predictors of the study composite endpoint. Conclusions In patients with MINOCA, the presence of NCA or 1–2 vessel MCAD was associated with better long-term clinical outcomes compared with patients with MCAD affecting 3 vessels or the LMS. Increased CRP concentrations on hospital admission were also a marker of worse clinical outcome during follow-up.