ABSTRACT
Introduction In November 2019, the first case of SARS-CoV-2 infection was reported in China, the first European case was declared 2 months later in January 2020. While the pediatric population seemed to be less affected by SARS-CoV-2, an alert was launched in April 2020 following multiple cases of multisystem inflammatory syndrome in children (MIS-C), secondary to SARS-CoV-2 infection. The presentation shares clinical features with Kawasaki disease but involves almost systematically cardiac dysfunction. Cardiac involvement is central in MIS-C and represents the main cause of morbidity. Objective In this study, we therefore aimed to assess the myocardial damage in patients with MIS-C using MRI during the acute phase as well as left ventricular and atrial longitudinal strain during the acute phase and after recovery. Method We performed a single-center prospective cohort and case-control study. Between September 2020 and January 2022, we included 39 patients hospitalized for MIS-C in our center. We performed left ventricular and atrial longitudinal 2D strain analysis on admission and during follow-up;the analysis was compared to a matched control population. Patients above 4 years old with increased troponin underwent cardiac MRI. Results Of 22 patients who underwent cardiac MRI, 14 (64%) presented myocardial edema and 6 (27%) late gadolinium enhancement, the latter being associated with myopericarditis and impaired LVEF (P<0.001), older patients (P=0.027) and elevated ferritin (P=0.03). We found a decrease in left ventricular and atrial longitudinal strain on admission as compared to controls with a significant improvement at 1 month post-discharge (P<0.0001). The alteration in LV strain persisted beyond one month according the comparison with the control population (P=0.01). Conclusion Only little is known about the long-term follow-up and prognosis in MIS-C patients. Our study demonstrated the myocardial inflammation during the acute phase of MIS-C as well as the impaired LA and LV myocardial deformation that persists for at least several weeks after the acute phase. Thus, we believe MRI and LV/LA strain could help us individualize our MIS-C patients follow-up.