Children With Acute Myocarditis Often Have Persistent Subclinical Changes as Revealed by Cardiac Magnetic Resonance

Background Many children presenting with myocarditis may not fully recover and have long‐term complications, including dilated cardiomyopathy. Magnetic resonance imaging (MRI) has a potential for early detection of persistent changes with long‐term implications, but is not performed routinely in the monitoring of myocarditis. Purpose To monitor adolescents who present with acute myocarditis using MRI and routine diagnostic tests over the short‐ to mid‐term. Study Type Prospective. Population Eighteen consecutive adolescents (median age 15.5, interquartile range 14.8–16.9 years, 78% male) with acute myocarditis. Field Strength A 3T scanner including cine steady‐state free precession (SSFP), dark‐blood T2‐weighted (T2W) images, and late gadolinium enhancement (LGE). Assessment The diagnosis of acute myocarditis was based on clinical symptoms and signs and MRI criteria (cine, T2‐W images, LGE). Follow‐up MRI was performed after median 7 months (range 6–9 months). Other routine diagnostic tests included electrocardiogram (ECG), high‐sensitivity troponin levels, transthoracic echocardiography, and Holter monitoring. Statistical Tests Fisher's exact test, Wilcoxon test for paired samples, Mann–Whitney test for independent samples, Kruskal–Wallis test. Results At baseline, 17 patients (94%) had elevated troponin levels and/or ST‐T changes on resting ECG; ECG showed depressed left ventricular ejection fraction (LVEF