Myocarditis in athletes: A clinical perspective

Myocarditis is an important cause of arrhythmias and sudden cardiac death (SCD) in both physically active individuals and athletes. Elite athletes seem to have an increased risk for viral infection and subsequent myocarditis due to increased exposure to pathogens (worldwide traveling/international competition) or impaired immune system (continuing training during infections/resuming training early thereafter, strenuous exercise training or competition, and exercising in extreme weather conditions). Initial clinical presentation is variable, but athletes characteristically express non-specific symptoms of fatigue, muscle soreness, increased heart rate at rest, as well as during exercise and reduced overall exercise capacity. Beyond resting electrocardiogram (ECG), cardiac biomarkers, echocardiography, and 24-hour Holter ECG, diagnostic work-up should include cardiac magnetic resonance imaging (CMR) assessing inflammation, oedema, and fibrosis by late gadolinium enhancement (LGE), respectively, as these measures are crucial for prognosis and sports eligibility. For patients with insufficient cardiac recovery, endomyocardial biopsy is recommended to clarify differential diagnoses and initiate specific treatment options. In uncomplicated cases with normal left ventricular function during acute phase and absent LGE, eligibility for sports can be attested to three months after clinical recovery. In those with persistent pathological findings, even after six months, the risk for SCD remains increased and resuming exercise beyond recreational activities can only be recommended individually based on course of disease, left ventricular function, arrhythmias, pattern of LGE in CMR, as well as intensity and volume of exercise performed during training and competition. For all athletes, follow-up examination should be performed yearly.