["The athlete's heart": most common electrocardiographic findings].

The morphological and functional cardiac adaptations induced by physical training may be reflected in several athlete's electrocardiographic variants. Rhythm and heart rate disturbances are the most common findings, and sinus bradycardia is the most frequent adaptation. Non-specific intraventricular conduction delay and incomplete right bundle branch block are also frequent, but other bundle branch and fascicular blocks are extremely rare. While the atrioventricular conduction may be prolonged, the occurrence of first degree and type I second degree atrioventricular blocks depends on the individual's susceptibility. Advanced second and third degree atrioventricular blocks are exceptional, and when present, the possibility of underlying heart disease must be excluded. High QRS voltage is more frequent in male athletes, but its correlation with left ventricular hypertrophy is low. The ST segment elevation in the so called "early repolarization" pattern is typical of the athlete's electrocardiogram. Vagotonic or high T wave voltages and U waves are also frequent when sinus bradycardia is present. Tachyarrhythmias and increased automatism arrhythmias are rare and usually benign. The increased vagal tone is responsible for the suppression of the physiological and ectopic pacemakers. While Wolff-Parkinson-White syndrome per se does not exclude an athlete from sports activity, the risk of a sudden death makes it mandatory to perform an exhaustive cardiac evaluation. We may conclude that no sport can be considered arrhythmogenic or as a predisposing factor for malignant ventricular arrhythmias.