This cluster of papers focuses on the aetiology, diagnosis, and management of myocarditis, with an emphasis on viral infections such as enterovirus and poliovirus. It discusses the use of cardiovascular magnetic resonance and endomyocardial biopsy in diagnosing myocarditis, as well as the role of immunosuppressive therapy in its management. The cluster also covers the epidemiology of viral myocarditis and its association with inflammatory cardiomyopathy and heart failure.