553 Myocarditis after COVID-19 vaccination—a case series

Abstract Myocarditis has been recognized as a rare complication of SARS-CoV-2 infection even in the absence of lung involvement and recent histological findings suggest that COVID-19-related myocardial damage may differ from other typical lymphocytic myocarditis associated with other viruses and could be possibly linked to diffuse infiltration of monocytes and macrophage leading to microvascular dysfunction and cell necrosis. SARS-CoV-2 vaccines have been well tolerated and associated with decreasing burden of disease in areas with high vaccination rates. Minor side-effects have been frequently described, mainly after second dose. Here, we report our findings in four male patients consistent with acute myocarditis at our Institutional Hospital; all four had recently received a second-dose mRNA vaccine. All presented with acute chest pain associated with biomarker evidence of myocardial injury and were hospitalized. None of them had a previous history of SARS-CoV2 infection. All of them showed markedly abnormal EKG findings with diffuse ST segment elevation and laboratory tests revealed elevated high-sensitivity (hs) troponin T levels and C-reactive protein with no peripheral eosinophilia. All patients underwent nasopharyngeal swabbing and the specimens were tested for common respiratory viruses by RT-PCR and resulted all negative. All patients underwent CMR scan during hospitalization. The hospital course was benign for all patients without evidence of arrhythmias or heart failure, in all cases we performed a conservative treatment with nonsteroidal anti-inflammatory drugs and colchicine with progressive normalization of troponin levels before discharge. Our cases presented features of acute myocarditis with a temporal association with the mRNA Covid-19 vaccination, in absence of other apparent causes (in fact none had viral prodromes) nor COVID-19 infection in the prior year. Several reports in the past months had suggested a possible association between the mRNA Covid-19 and myocarditis, most of the cases presenting in young males, after the second dose and with a favourable course. Thus, given the potential risk of cardiac involvement after SARS-CoV-2 infection even in younger adults, the risk-benefit decisions favours vaccination for population immunity. Despite this, the potential mechanisms of SARS-CoV-2 vaccine-related myocarditis seem different from the previously described eosinophilic myocarditis after smallpox vaccination remain unclear and vaccine adverse event reporting remains of high importance. Figure 1 shows one acute MRI scan with STIR, T2-map and LGE in short-axis and apical four-chamber view.