Early Comprehensive Cardiovascular Magnetic Resonance Imaging in Patients With Myocardial Infarction With Nonobstructive Coronary Arteries.

OBJECTIVES The objective of the SMINC-2 (Stockholm Myocardial Infarction With Normal Coronaries 2) study was to determine if more than 70% of patients with myocardial infarction with nonobstructed coronary arteries (MINOCA), investigated early with comprehensive cardiovascular magnetic resonance (CMR), could receive a diagnosis entirely by imaging. BACKGROUND The etiology of MINOCA is heterogeneous, including coronary, cardiac, and noncardiac causes. Patients with MINOCA, therefore, represent a diagnostic challenge where CMR is increasingly used. METHODS The SMINC-2 study was a prospective study of 148 patients with MINOCA imaged with 1.5-T CMR with T1 and extracellular volume mapping early after hospital admission, compared to 150 patients with MINOCA imaged using 1.5-T CMR without mapping techniques from the SMINC-1 study as historic controls. RESULTS CMR was performed at a median of 3 (SMINC-2) versus 12 (SMINC-1) days after hospital admission. In total, 77% of patients received a diagnosis with CMR imaging in the SMINC-2 study compared to 47% in the SMINC-1 study (p < 0.001). Compared to SMINC-1, CMR in SMINC-2 detected higher proportions of myocarditis (17% vs. 7%; p = 0.01) and takotsubo syndrome (35% vs. 19%; p = 0.002) but similar proportions of myocardial infarction (22% vs. 19%; p = 0.56) and other cardiomyopathies (3% vs. 2%; p = 0.46). CONCLUSIONS The results of the SMINC-2 study show that 77% of all patients with MINOCA received a diagnosis when imaged early with CMR, including advanced tissue characterization, which was a considerable improvement in comparison to the SMINC-1 study. This supports the use of early CMR imaging as a diagnostic tool in the investigation of patients with MINOCA. (Stockholm Myocardial Infarction With Normal Coronaries [SMINC]-2 Study on Diagnosis Made by Cardiac MRI [SCMINC-2]; NCT02318498).