Cardiac magnetic resonance imaging for the diagnosis of acute myocarditis mimicking a myocardial infarction

Abstract

Acute myocarditis frequently mimics an acute myocardial infarction, and its diagnosis is a clinical challenge. To describe the characteristics of cardiac magnetic resonance imaging in patients with acute myocarditis hospitalized with a diagnosis of ST-segment elevation myocardial infarction. Twenty-four patients aged 33 ± 11 years (21 men) with a definitive diagnosis of acute myocarditis hospitalized with a presumptive diagnosis of ST-segment elevation myocardial infarction, in whom a coronary angiogram excluded significant atherosclerotic coronary lesions, were included. Cardiac magnetic resonance imaging with cine-resonance images was performed to assess global and regional ventricular function, and to study myocardial tissue characteristics. T2-STIR sequences were used for the assessment of oedema and late gadolinium enhancement for necrosis/fibrosis. Patients had high levels of total CK, CK-MB, troponin I, brain natriuretic peptide and C-reactive protein. Cardiac magnetic resonance imaging revealed myocardial edema and late gadolinium enhancement was identified in all patients. The edema was transmural in 86% and subepicardial in 14%. Enhancement was subepicardial in 74% of patients and intramural in 26%. It was located in the inferior and lateral walls of the left ventricle in 93%, without affecting the endocardium. In all patients, two of three Lake Louise criteria were met, and an acute myocarditis was diagnosed. Cardiac magnetic resonance imaging is the diagnostic method of choice for diagnosing acute myocarditis when it mimics an acute myocardial infarction.