Myocarditis with ventricular tachycardia following bivalent COVID-19 mRNA vaccination.

This report describes a case of probable myocarditis following bivalent COVID-19 vaccination. Although this was the patient's fifth COVID-19 vaccination, it was the first dose of bivalent vaccine. The myocarditis may have been due to direct damage caused by an increase in free spike protein. This case demonstrates that postvaccination hypercytokinemia may cause myocarditis, leading to potentially fatal arrhythmia. Colchicine, which suppresses hypercytokinemia, may be effective in such cases and preferable to steroids, particularly in elderly patients. This adverse reaction is difficult to diagnose using conventional methods, and multimodality diagnostics are important, including myocardial scintigraphy and cardiac magnetic resonance imaging.