Acute myocarditis (AM) is a rare disease of the heart muscle. Diagnosis involves a combination of clinical, biological and radiological findings. Cardiac MRI is a highly effective diagnostic tool. Recent studies in both pediatric and adult patients have shown a connection between the location of fibrosis (scarring) detected on MRI and subsequent health issues. Patients with AM are at risk of developing dilated cardiomyopathy and major cardiovascular events.

Our objective is to investigate whether the location of fibrosis lesions found on cardiac MRI differs between children with and without cardiac dysfunction.

This retrospective study was conducted at Amiens University Hospital. The study included children diagnosed with AM who underwent both an initial cardiac MRI and a follow-up MRI. We recorded the number of segments showing edema and late enhancement (scarring) on the MRI images. Additionally, we assessed cardiac function and collected all relevant clinical and biological data.

A total of 31 children with AM, with an average age of 12years, were included in the study. Most of the children exhibited typical involvement of the left ventricle in the inferolateral region. We found no association between the typical MRI localization and initial cardiac dysfunction (OR=0.25 [0.04, 1.24], P=0.091). However, patients with extensive edema experienced a decrease in subsequent MRI sequelae (scarring) by 0.69 [0.42, 0.97] per additional affected segment (P=0.029). Furthermore, children with more than 2 affected segments had longer hospital stays (OR=4.8 [1.03; 26.09], P=0.045) (Fig. 1).

The presence of initial edema appears to have a protective effect against subsequent MRI sequelae (scarring). Further studies are necessary to identify a specific subgroup of patients who are at a higher risk of developing dilated cardiomyopathy or major cardiovascular events.