Acute myocarditis associated with COVID-19 vaccination: A case report

Recently, new vaccine platforms-including mRNA vaccines for coronavirus disease 2019 (COVID-19) have been given emergency use authorization in Japan. Here, we present a rare case of myocarditis following a COVID-19 vaccine. In this case, myocarditis was confirmed by cardiac magnetic resonance imaging, endomyocardial biopsy, and troponin levels. The degree of myocardial inflammation in the endomyocardial biopsy samples was mild and the patient's clinical course was not severe. Although the pathology of myocarditis in this case was mild, further investigation would be needed. <Learning objective: Vaccination for coronavirus disease 2019 is advancing worldwide, but post-vaccination myocarditis is getting attention as a rare side effect. Although the myocarditis in this case was mild, the pathogenesis of the disease is unclear and needs to be thoroughly investigated in the vaccination.>