Athletes often exhibit structural and electrical cardiac adaptations that are influenced by several factors including sporting discipline, gender and ethnicity. These changes are considered physiological and reversible in most cases. However, recent data indicate that atrial and right ventricular remodeling in athletes may represent pathological changes leading to arrhythmias. Sudden cardiac death in athletes is a rare but dramatic event. The differential diagnosis between the athlete's heart and heart diseases that are potential etiologies of sudden cardiac death, such as hypertrophic cardiomyopathy, may be challenging. New recommendations about electrocardiogram interpretation in athletes may help to improve prevention strategies.