Pathological Evidence for SARS-CoV-2 as a Cause of Myocarditis: JACC Review Topic of the Week

To investigate whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)–induced myocarditis constitutes an important mechanism of cardiac injury, a review was conducted of the published data and the authors’ experience was added from autopsy examination of 16 patients dying of SARS-CoV-2 infection. Myocarditis is an uncommon pathologic diagnosis occurring in 4.5% of highly selected cases undergoing autopsy or endomyocardial biopsy. Although polymerase chain reaction–detectable virus could be found in the lungs of most coronavirus disease-2019 (COVID-19)–infected subjects in our own autopsy registry, in only 2 cases was the virus detected in the heart. It should be appreciated that myocardial inflammation alone by macrophages and T cells can be seen in noninfectious deaths and COVID-19 cases, but the extent of each is different, and in neither case do such findings represent clinically relevant myocarditis. Given its extremely low frequency and unclear therapeutic implications, the authors do not advocate use of endomyocardial biopsy to diagnose myocarditis in the setting of COVID-19.