Baseline and Follow-up Cardiac Magnetic Resonance Findings in Pediatric Acute Myocarditis: A Single-center Experience

Objectives: Acute myocarditis in children has a broad clinical spectrum, and cardiac magnetic resonance (CMR) is an important non-invasive tool for diagnosis and follow-up. This study aimed to evaluate baseline and follow-up CMR findings in pediatric acute myocarditis and their relationship with clinical and laboratory markers of myocardial injury and inflammation. Materials and Methods: This single-center retrospective study included pediatric patients who underwent CMR for clinically suspected acute myocarditis. Demographic characteristics, presenting symptoms, laboratory data, electrocardiographic and echocardiographic findings, and CMR parameters were collected. Follow-up CMR was available in a subset of patients to assess interval changes in myocardial tissue characteristics, including native T1 and T2 mapping values, extracellular volume (ECV), late gadolinium enhancement (LGE), and left ventricular ejection fraction (LVEF). Results: Baseline CMR was performed in 139 pediatric patients with suspected acute myocarditis. Median LVEF was 50% interquartile range (IQR, 33–58): reduced systolic function (LVEF <55%) was observed in 64.7% of the cohort. LGE was identified in 91.4% of patients, with a median extent of 4% (IQR, 3–5). Follow-up CMR performed in 40 patients showed significant improvements in LVEF, native T1 and T2 relaxation times, ECV, and LGE extent (all p<0.05). All 40 patients had LGE at baseline, and LGE remained detectable in 32 patients (80%) at follow-up. Conclusion: Multiparametric CMR provides comprehensive insight in pediatric acute myocarditis. Significant improvement in ventricular function and tissue characterization parameters was observed at follow-up, although LGE remained detectable in 80% of patients. These findings support the role of CMR in both the initial evaluation and follow-up of pediatric myocarditis.