Background. Cardiac involvement in multisystem inflammatory syndrome in children may have a spectrum ranging from mild disease to severe heart failure due to fulminant myocarditis. Cardiac involvement usually resolves after clinical recovery. However, the adverse effects of myocarditis on cardiac function after recovery are not fully known. This study aims to investigate cardiac involvement by performing cardiac magnetic resonance imaging (MRI) after the acute and recovery periods.

Methods. 21 patients with clinical and laboratory signs of myocarditis, including left ventricular systolic dysfunction, mitral regurgitation, elevated troponin T, elevated N-terminal pro-B-type natriuretic peptide and electrocardiographic changes, who had given consent for cardiac MRI, underwent cardiac MRI after completion of the acute and recovery phases.

Results. When compared to 16 patients with normal cardiac MRI, five patients with cardiac fibrosis on MRI were older, had greater body mass indexes, lower leucocyte counts, lower neutrophil counts, higher blood urea nitrogen levels and higher creatinine levels. Cardiac fibrosis on MRI was located in the posterior right ventricle insertion point and in mid ventricular septum.

Conclusions. Adolescence and obesity appear as risk factors for the development of fibrosis as a late-term sequela of myocarditis. Furthermore, future studies reporting the follow-up data of patients with fibrosis are necessary to predict and manage adverse outcomes.

Keywords: cardiac involvement, cardiac magnetic resonance, fibrosis, multisystem inflammatory syndrome in children, myocarditis