Comparing myocardial injury patterns and outcomes in cardiac magnetic resonance imaging between COVID-19- and non-COVID-19-related myocarditis

Purpose: Despite the low incidence of COVID myocarditis, its influence on outcomes is substantial. The pivotal role of cardiac magnetic resonance (CMR) in diagnosing myocarditis is considered to be associated with disease prognosis. The primary objective of this study was to conduct a comparative analysis of myocardial injury patterns, CMR pathologic features, outcomes, and their correlation with CMR findings in COVID- and non-COVID-related myocarditis. Material and methods: This historical cohort study involved 124 patients diagnosed with myocarditis (COVID-19 or non-COVID-19), who underwent CMR between 2018 and 2021. The COVID group consisted of 70 individuals with a definite history of COVID-19 infection within 4 weeks, and the non-COVID group comprised 54 individuals who had no prior exposure to the SARS-CoV-2 virus. All patients were monitored for one year to assess the incidence of major adverse cardiovascular events (MACE). Additionally, baseline and follow-up echocardiography data were obtained with a minimum 3-month interval. Extension of late gadolinium enhancement (LGE) was significantly greater in COVID group. Finally, the incidence of MACE and mean event-free survival did not have significant difference between two groups. Conclusions: Although CMR findings differed between the 2 groups, there was no significant difference in the risk of MACE or survival during one-year follow-up. Notably, LV and RV dysfunction were more prevalent in the non-COVID group, while extension of LGE was greater in the COVID group.