Sudden deaths in young active people and athletes are distinctly uncommon and frequently related to highly visible cardiovascular conditions including hypertrophic cardiomyopathy and congenital coronary anomalies. Myocarditis is also a cause of sudden death in the young, but frequently under-recognized clinically, and therefore deserving of the present analysis. Two large registries were interrogated for cases of myocarditis, and clinical, demographic, and pathologic findings were assessed. Of 97 cases of myocarditis identified, ages were 19.3 ± 6.2 years, 76% male, and 58 were physically active at or near the time of death. Almost one-half of the 97 cases (47%) had a viral prodrome or symptoms (i.e., syncope, malaise, chest pain or palpitations). Nine were evaluated by cardiologists, but in none was a diagnosis of myocarditis established before death. The inflammatory cellular infiltrate was predominantly lymphocytic (67%), was most frequently multifocal (59%) and involved the conduction system (including atrioventricular node), 38%. In conclusion, myocarditis is an important but under-recognized cause of sudden death in young people including competitive athletes. Clinical diagnosis is difficult because symptoms are nonspecific and often ignored, requiring high index of suspicion for diagnosis. Our data support the ACC/AHA consensus guidelines recommending removal of individuals with myocarditis from competitive sports during recovery. Selective examination of conduction systems showed a number of cases with involvement of myocarditis, suggesting a novel mechanism for sudden death.
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