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

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.

To monitor adolescents who present with acute myocarditis using MRI and routine diagnostic tests over the short- to mid-term.

Prospective.

Eighteen consecutive adolescents (median age 15.5, interquartile range 14.8-16.9 years, 78% male) with acute myocarditis.

A 3T scanner including cine steady-state free precession (SSFP), dark-blood T₂ -weighted (T₂ W) images, and late gadolinium enhancement (LGE).

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.

Fisher's exact test, Wilcoxon test for paired samples, Mann-Whitney test for independent samples, Kruskal-Wallis test.

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<50%) in four patients (22%). At follow-up there was a complete recovery in 16 patients (89%) observed with routinely performed tests, with two cases of persistent ventricular arrhythmia. Despite normal left ventricular volume and LVEF, MRI disclosed ongoing active inflammation in five patients (28%), healed myocarditis with persistent scars in eight patients (44%), and complete resolution of initially observed changes in five patients (28%).

In children with acute myocarditis, despite normalization of other routinely assessed parameters (including LVEF), there is a high prevalence of persistent MRI changes showing ongoing disease or remnant scars at follow-up. MRI may allow early detection and prevention of long-term complications of myocarditis in the follow-up care of children with acute myocarditis.

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020. J. Magn. Reson. Imaging 2020;52:488-496.