[Pathophysiology of atrioventricular conduction disturbances in sports practitioners]

In athletes practicing endurance sports, atrioventricular conduction disturbances may be physiological. This holds true for first-degree atrioventricular blocks, type 1 second-degree atrioventricular blocks, and slight ventricular activation delays (slurred S wave in V1). On the contrary, right (RBBB) and left bundle branch blocks (LBBB) and fascicular blocks (left anterior [LAH] and left posterior hemiblocks [LPH]), either isolated or associated with RBBB, are rare in asymptomatic athletes. The latter can be the consequence of structural heart disease or primary degeneration of the intraventricular conduction system (Lev-Lenègre disease). In our experience, LPH and LPH+RBBB have always a pattern of familial recurrence. LAH+RBBB may be familial (40-60%). Isolated RBBB is rarely familial. LBBB is never familial. Families with hereditary conduction disorders may also have a history of juvenile sudden death. Patients with LBBB may show coronary artery anomalies. The long-term prognosis of intraventricular conduction disorders in asymptomatic subjects, without apparent heart disease, is unknown.