Diagnostic and Prognostic Role of Cardiac Magnetic Resonance in MINOCA: Systematic Review and Meta-Analysis

Background: Myocardial infarction with nonobstructive coronary arteries (MINOCA) is common in current clinical practice. Cardiac magnetic resonance (CMR) plays an important role in its management and is increasingly recommended by all the current guidelines. However, the prognostic value of CMR in patients with MINOCA is still undetermined. Objectives: The purpose of this study was to determine the diagnostic and prognostic value of CMR in the management of patients with MINOCA. Methods: A systematic review was performed to identify studies reporting the results of CMR findings in patients with MINOCA. Random effects models were used to determine the prevalence of different disease entities: myocarditis, myocardial infarction (MI), or takotsubo syndrome. Pooled odds ratios (ORs) and 95% CIs were calculated to evaluate the prognostic value of CMR diagnosis in the subgroup of studies that reported clinical outcomes. Results: A total of 26 studies comprising 3,624 patients were included. The mean age was 54.2 ± 5.3 years, and 56% were men. MINOCA was confirmed in only 22% (95% CI: 0.17-0.26) of the cases and 68% of patients with initial MINOCA were reclassified after the CMR assessment. The pooled prevalence of myocarditis was 31% (95% CI: 0.25-0.39), and takotsubo syndrome 10% (95% CI: 0.06-0.12). In a subgroup analysis of 5 studies (770 patients) that reported clinical outcomes, CMR diagnosis of confirmed MI was associated with an increased risk of major adverse cardiovascular events (pooled OR: 2.40; 95% CI: 1.60-3.59). Conclusions: In patients with MINOCA, CMR has been demonstrated to add an important diagnostic and prognostic value, proving to be crucial for the diagnosis of this condition. Sixty-eight percent of patients with initial MINOCA were reclassified after the CMR evaluation. CMR-confirmed diagnosis of MINOCA was associated with an increased risk of major adverse cardiovascular events at follow-up.