Differentiating the athlete's heart from hypertrophic cardiomyopathy.

PURPOSE OF REVIEW: Exercise-induced cardiac remodeling (EICR), or athlete's heart, refers to the cardiac structural and functional adaptations to exercise training. Although the degree of physiological left ventricular hypertrophy (LVH) is typically mild in trained athletes, in some LVH is substantial enough to prompt concern for hypertrophic cardiomyopathy (HCM). This review summarizes the available imaging tools to help make this important clinical distinction.

RECENT FINDINGS: Advanced echocardiographic techniques (tissue and Doppler and speckle tracking) and cardiac magnetic resonance imaging are being investigated to aid in the differentiation of EICR and HCM in 'gray-zone' hypertrophy cases. Higher early diastolic (E') velocity by tissue Doppler imaging has been documented in athletes. HCM patients have been found to have lower global longitudinal strain (GLS) when compared with athletes with LVH. Analysis of twisting and untwisting of the LV with speckle tracking may also help distinguish athlete's heart from HCM. Studies of the expected degree and time course of LVH regression after exercise cessation (in the setting of prescribed detraining) are needed as this may be a useful adjunct to determine the cause of LVH in particularly challenging cases.

SUMMARY: Ongoing research with novel imaging techniques continues to improve the ability to distinguish athlete's heart from HCM in situations of 'gray-zone' hypertrophy.