Differential diagnosis between 'athlete's heart' and cardiomyopathies

Physiological adaptation to exercise results in a series of electrical, structural, and functional cardiac changes, broadly named 'athlete's heart'. Symmetrical enlargement of all cardiac chambers and mild increase in wall thickness are common findings in highly trained athletes. Typical electrocardiogram (ECG) features include sinus bradycardia, first-degree atrioventricular (AV) block, isolated voltage criteria for right and left ventricular hypertrophy and early repolarisation. Cardiac remodelling may be marked in some athletes, and it may be challenging to distinguish physiological adaptation from cardiac conditions at risk of sudden cardiac death (SCD), such as cardiomyopathies. Differential diagnosis often requires a comprehensive assessment starting from a detailed personal and family history to baseline tests, such as ECG and echocardiogram. In some cases, second-line tests, such as prolonged ambulatory ECG monitoring, exercise tolerance test and cardiovascular magnetic resonance are required. In this narrative review, we will explore the key features of physiological cardiac adaptation to exercise, and we will focus on differential diagnosis between 'athlete's heart' and cardiomyopathies.