The heart of an athlete

Athletes commonly develop what is regarded as a benign increase in cardiac mass in response to physical training. However, prolonged training may lead to a degree of cardiac remodeling that mimics hypertrophic cardiomyopathy (HCM). Left ventricular hypertrophy (LVH) can be defined echocardiographically as a left ventricular wall thickness (LVWT) of greater than 12mm. A LVWT of 12-16mm represents a “grey zone” of overlap between physiological LVH and mild HCM. In this situation, an enlarged left ventricular (LV) cavity size (>56mm) in the absence of symptoms is highly suggestive of physiological LVH. Other markers that favor physiological LVH include normal LV diastolic function, a concentric pattern of hypertrophy, left atrial size <50mm and absence of LV outflow tract obstruction. Where diagnostic doubt remains, Holter monitoring, cardiopulmonary exercise testing, cardiac magnetic resonance imaging or trial of detraining can be considered. The correct diagnosis is essential as HCM increases an athlete’s risk of sudden cardiac death and may result in disqualification from professional sport.