Specific Cardiovascular Diseases and Competitive Sports Participation: Myocarditis and Myocardial Fibrosis

According to recent epidemiologic studies, myocarditis represents one of the major causes of sudden cardiac death among young competitive athletes. Myocarditis can be caused by infectious agents (with viral myocarditis being the leading cause), systemic auto-immune diseases, medical drugs and toxic agents. Since myocarditis is an acquired disease, systematic screening programs will fail to depict this disease. Nevertheless, an adapted prevention can decrease its incidence in athletes. Information on not to train in case of infection and systemic symptoms and on the potential adverse effects of doping agents and recreational drugs is essential for the prevention of myocarditis in athletes. The diagnosis of myocarditis is challenging, due to the heterogeneity of its clinical presentation. Cardiovascular symptoms, ECG and echocardiographic changes, as well as elevation of troponin are rather unspecific. If these first line examinations are suggestive, cardiac MRI should be performed, and the diagnosis should be based on the Lake Louise Consensus criteria. Endomyocardial biopsy, the gold standard for diagnosis, should be limited to recent-onset, high-risk major clinical syndromes not responding to conventional medical therapy. In case of myocarditis, the treatment is essentially symptomatic and based on the management of arrhythmic and heart failure complications. Sport restriction is of course warranted in order to prevent potential lethal arrhythmias and to decrease the risk of negative ventricular remodelling. Athletes with a diagnosis of myocarditis should be restricted from exercise programs for a period of 3–6 months. Asymptomatic patients might be able to resume training and competition if serum markers of myocardial injury, inflammation, and heart failure have normalized, if ventricular systolic function has returned to the normal range, and if no significant arrhythmia occurs on a 24-h ECG monitoring and during an exercise test.