ABSTRACT
OBJECTIVES: The clinical manifestations of COVID-19 associated cardiac complications are heterogeneous, ranging from asymptomatic to severe symptoms, including arrhythmias and cardiogenic shock. For COVID-19 patients with cardiac sequela, only a small subset of patients have myocarditis; the pathogenesis of cardiac sequela caused by SARS-CoV-2 other than microthrombi associated sequela remains to be determined. METHODS: Retrospective analysis of 71 heart autopsy specimens from COVID-19 and putative COVID-19 in the NIH COVID Digital Pathology Repository. RESULTS: The most consistent observation was localized myocardial cell death not associated with either myocarditis or microthrombi. Red blood cells were typically absent from capillaries but, when observed, were predominately in linear clusters (stacks) of adjacent cells. CONCLUSIONS: Based on our retrospective analysis, we propose that localized ischemia and subsequent cell death by anoxia contributes to the cardiac pathogenesis in some COVID-19 patients. We propose two new models predicting vasoconstriction of cardiac pericyte cells induced by elevated histamine from hyper-activated mast cells or direct infection. We propose that impeded blood flow and cell death by anoxia are initial steps in the development of SARS-CoV-2 induced cardiac injury in COVID-19 patients independent of microthrombi or myocarditis.