Evolution of acute myocarditis in a pediatric population: An MRI based study.

Background: Cardiac Magnetic Resonance (CMR) data regarding myocarditis presentation and disease course is still lacking in pediatric patients. We evaluate baseline CMR and evolution of functional and tissue abnormalities in children with acute myocarditis.

Methods: CMR was performed in 125 patients with clinical diagnosis of acute myocarditis. Clinical follow-up was performed for a median of 498 (214-923) days.

Results: LVEF was depressed (<55%) in 56 cases (45%) upon baseline CMR. LGE was found in 93 patients (77%) of cases. LGE was exclusively subepicardial in 29 patients (23%), while other LGE patterns (midwall/mixed) were present in 64 (51%). CMR was repeated in 92 (74%) patients. 67% presented recover of function at a median of 170 (70-746) days after onset of symptoms. Midwall/mixed LGE pattern had a statistically significant correlation with absent recover of function (OR 0.20 p 0.036). Thirteen patients (16%) had recovery from LV dysfunction but with persistence of LGE. Sub-epicardial pattern of LGE (OR 3.33, 95% CI 1.08-10.2, p = 0.036) and the presence of fever at admission (OR 4.67, 95% CI 1.16-18.7, p = 0.03) were associated with a significantly higher likelihood of complete normalization while midwall/mixed LGE pattern was associated with non-recovery.

Conclusions: In pediatric myocarditis, midwall/mixed LGE pattern is associated with absent recover of function. Patients with recover of function may still have persistence of LGE, while a complete recovery from functional and tissue abnormalities is found only in a third of patients. Midwall/mixed pattern of LGE at first MRI was associated to worse outcome.