Prognostic Role of CMR and Conventional Risk Factors in Myocardial Infarction With Nonobstructed Coronary Arteries

This study sought to assess the prognostic impact of cardiac magnetic resonance (CMR) and conventional risk factors in patients with myocardial infarction with nonobstructed coronaries (MINOCA).

Myocardial infarction with nonobstructed coronary arteries (MINOCA) represents a diagnostic dilemma, and the prognostic markers have not been clarified.

A total of 388 consecutive patients with MINOCA undergoing CMR assessment were identified retrospectively from a registry database and prospectively followed for a primary clinical endpoint of all-cause mortality. A 1.5-T CMR was performed using a comprehensive protocol (cines, T2-weighted, and late gadolinium enhancement sequences). Patients were grouped into 4 categories based on their CMR findings: myocardial infarction (MI) (embolic/spontaneous recanalization), myocarditis, cardiomyopathy, and normal CMR.

CMR (performed at a median of 37 days from presentation) was able to identify the cause for the troponin rise in 74% of the patients (25% myocarditis, 25% MI, and 25% cardiomyopathy), whereas a normal CMR was identified in 26%. Over a median follow-up of 1,262 days (3.5 years), 5.7% patients died. The cardiomyopathy group had the worst prognosis (mortality 15%; log-rank test: 19.9; p < 0.001), MI had 4% mortality, and 2% in both myocarditis and normal CMR. In a multivariable Cox regression model (including clinical and CMR parameters), CMR diagnosis of cardiomyopathy and ST-segment elevation on presentation electrocardiogram (ECG) remained the only 2 significant predictors of mortality. Using presentation with ECG ST-segment elevation and CMR diagnosis of cardiomyopathy as risk markers, the mortality risk rates were 2%, 11%, and 21% for presence of 0, 1, and 2 factors, respectively (p < 0.0001).

In a large cohort of patients with MINOCA, CMR (median 37 days from presentation) identified a final diagnosis in 74% of patients. Cardiomyopathy had the highest mortality, followed by MI. The strongest predictors of mortality were a CMR diagnosis of cardiomyopathy and ST-segment elevation on presentation ECG.