Introduction: The risk of myocarditis after mRNA vaccination against COVID-19 has emerged, recently. Current evidence suggests that young male patients are predominantly affected. In the majority of the cases only mild symptoms were observed. However, little is known about mRNA vaccination related myocarditis cardiac magnetic resonance (CMR) imaging patterns and their differences to classical viral myocarditis in the acute phase of inflammation.

Methods: 10 mRNA vaccination associated myocarditis patients were retrospectively enrolled in this study and compared to 10 patients suffering from viral myocarditis, matched with age, sex, comorbidities and laboratory markers. All patients (n = 20) were hospitalized and underwent a standardized clinical examination as well as an echocardiography and a CMR. Both, clinical and imaging findings were compared between both groups.

Results: All patients described chest pain as the leading reason for their initial presentation. CMR volumetric and functional parameters did not differ significantly between both groups. In all cases the lateral left ventricular wall showed late gadolinium enhancement without significant differences in terms of the localisation or in-depth tissue characterization.

Conclusions: COVID-19 mRNA vaccination associated myocarditis does not show specific CMR patterns during the very acute stage in the most affected patient group of young male patients. The observed imaging markers are closely related with regular viral myocarditis and did not yield any evidence implying adverse outcomes in the investigated patient group.