ABC | Volume 115, Nº1, July 2020

Short Editorial Hossri AV conduction disorders in endurance athletes Arq Bras Cardiol. 2020; 115(1):78-79 acceleration and deceleration in athletes. The duration of dynamic ventricular repolarization (DVR) and coupling with RR interval are related to autonomic control and electrical myocardial stability. The phase rectification of the series with RR interval separates the acceleration and deceleration phases, reflecting sympathetic and parasympathetic influences on heart rate, respectively, where they observed that these have a longer ventricular repolarization duration for all RR interval durations. In athletes, DVR variability decreases as the RR interval increases, indicating a beneficial effect of physical fitness on the stability of repolarization and also the evaluation of RR interval using a start or peak wave approach as fiducial points providing proper accurate results for the analysis of physiological variation of the beat-to-beat interval. 13,14 Although AV conduction disorders have been repeatedly documented in athletes, the dynamic adaptation of AV conduction to the cardiac cycle in this population still needs clarification. In the general population, AV duration varies dynamically according to the RR interval duration, characterizing an accordion-like effect. However, in athletes, autonomic remodeling can influence dynamic AV conduction in the adaptation of the RR interval, leading to a different behavior from AV conduction, in response to the variation of the RR interval related to time. The study by Benchimol-Barbosa et al. 15 evaluated beat-by-beat variability of AV conduction time (AVCT) and RR interval in elite runners and in healthy sedentary individuals, at rest, with the objective of evaluating the effect of physical fitness on the duration of spontaneous coupling of AVCT to the RR interval. In this study, athletes had mean RR values and RR standard deviations significantly higher than controls and the RR-AVCT slope on controls and athletes resulted in significant differences between groups, demonstrating that this RR-AVCT slope decreases as metabolic capacity (MET) increases. We believe that some mechanism of intrinsic organic protection is activated when the individuals suffer, due to chronic intense exercising, these physiological adaptations and develop, through this discrepant response, a defense tomaintain specialized cardiac conduction. It is still necessary to investigate the potential impact of current findings in clinical settings, such as a marker for supraventricular tachyarrhythmias, particularly AV nodal reentry arrhythmia and atrial fibrillation. Finally, we observed that the intriguing finding in the Benchimol-Barbosa 15 study was precisely the disagreement between the dynamic coupling of AVCT and denoting the different responses between athletes and sedentary people regarding the behavior of PR and RR intervals. Such observations deserve further investigation and follow-up on the potential effects of high-intensity training and improvements in the clinical guidelines for this population. 1. Batlouni M, Ghorayeb N, Armaganijan, D, Meneghello RS. Electrocardiographic changes in professional athletes. II Rhythm and conduction disorders. Arq Bras Cardiol. 1980;35(3):187-95. 2. ZehenderM, Meinertz T, Keul J, Just H. ECGvariants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance. 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