Electroanatomical Mapping May Identify Concealed Arrhythmogenic Cardiomyopathy in Endurance Athletes With Complex Ventricular Arrhythmias

Highly trained endurance athletes can develop complex ventricular arrhythmias despite normal structural cardiac imaging, creating major diagnostic challenges. This case series describes 3 young cyclists presenting with symptomatic ventricular arrhythmias from the right ventricle (RV), in whom conventional investigations, including transthoracic echocardiography and cardiac magnetic resonance, revealed no structural abnormalities. Prolonged rhythm monitoring prompted electroanatomical mapping, which revealed discrete to diffuse low-voltage areas across the RV outflow tract, RV inferior wall, and apex; findings compatible with an arrhythmogenic substrate and raising the possibility of early or concealed arrhythmogenic cardiomyopathy. All 3 athletes had long-standing exposure to high-intensity endurance training, which may be relevant in susceptible individuals, although no causal relationship can be inferred from these cases. These observations highlight the limitations of relying solely on conventional imaging in athletes with persistent symptomatic arrhythmias and suggest that, in carefully selected cases, prolonged rhythm monitoring and electroanatomical mapping may offer complementary diagnostic insights when concealed arrhythmogenic cardiomyopathy is suspected.