Multisystem Inflammatory Syndrome in Children　- A New Syndrome Complicated With Acute Heart Failure Following Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a rare syndrome temporally related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). MIS-C shares similarities with Kawasaki disease, but left ventricular dysfunction is more common in MIS-C.Methods and Results:This study reports the case of a 16-year-old Japanese male patient with MIS-C. Although the initial presentation was severe with circulatory and respiratory failure, the patient recovered completely. Endomyocardial biopsy showed active myocarditis with fibrosis. Immunoglobulin treatment was useful for recovery. CONCLUSIONS: This is the first reported case of MIS-C in Japan. Cardiologists should be aware of MIS-C, a new disease, occurring during the global SARS-CoV-2 pandemic.