Ionic mechanisms and vectorial model of early repolarization pattern in the surface electrocardiogram of the athlete

The electrocardiogram (ECG) of the athlete displays particular characteristics as a consequence of both electrophysiological and autonomic remodeling of the heart that follows continued physical training. However, doubts persist on how these changes directly interact during ventricular activation and repolarization ultimately affecting surface ECG waveforms in athletes.

This article considers an in deep rationale for the electrocardiographic pattern known as early repolarization based on both electrophysiological mechanisms at cellular level and the vectorial theory of the cardiac activation.

The mechanism by which the autonomic remodeling influences the cardiac electrical activation is reviewed and an insight model of the ventricular repolarization based on ionic models and the vectorial theory of the cardiac activation is proposed.

Considering the underlying processes related to ventricular electrical remodeling, we propose that, in athletes' heart: 1) vagal modulation increases regional electrophysiological differences in action potential phases 1 and 2 amplitudes, thus enhancing a voltage gradient between epicardial and endocardial fibers; 2) this gradient affects depolarization and repolarization timing sequences; 3) repolarization wave front starts earlier on ventricular wall and partially overcomes the end of depolarization causing an upward displacement of the J-point, ST segment elevation, and inscription of magnified T-waves amplitudes leading to characteristic surface ECG waveform patterns.

In athletes, the association between epicardial to endocardial electrophysiological differences and early repolarization ECG pattern can be demonstrated by the vectorial theory of the ventricular activation and repolarization.