Myocarditis in the Athlete: Arrhythmogenic Substrates, Clinical Manifestations, Management, and Eligibility Decisions.

Myocarditis is as an important cause of sudden cardiac death (SCD) among athletes. The incidence of SCD ascribed to myocarditis did not change after the introduction of pre-participation screening in Italy, due to the transient nature of the disease and problems in the differential diagnosis with the athlete's heart. The arrhythmic burden and the underlying mechanisms differ between the acute and chronic setting, depending on the relative impact of acute inflammation versus post-inflammatory myocardial fibrosis. In the acute phase, ventricular arrhythmias vary from isolated ventricular ectopic beats to complex tachycardias that can lead to SCD. Atrioventricular blocks are typical of specific forms of myocarditis, and supraventricular arrhythmias may be observed in case of atrial inflammation. Athletes with acute myocarditis should be temporarily restricted from physical exercise, until complete recovery. However, ventricular tachycardia may also occur in the chronic phase in the context of post-inflammatory myocardial scar.