Analysis of the Early Repolarization in Competitive Athletes: Comparison Between the Notch and The Slur
Authors: Djellaoudji A. 
Published: June 2021

Early repolarization is currently defined by the presence of notch or slur, at the end of QRS complex, greater ≥ than 0.1 mV in two contiguous leads, and the ST-segment elevation is not necessary for diagnosis. Several studies have confirmed that early repolarization on the electrocardiogram has been associated with an increased risk of sudden arrhythmic death either in the general population or in athletes. However, no study has evaluated the prevalence of this anomaly, using the current definition of early repolarization, in the population of Algerian or North African athletes, no study analyzed notches and slurs separately, and no study compared them. The main objective of our study is to determine the prevalence of ER in an Algerian population of competitive athletes. The secondary objective was to compare the end-QRS Notching and Slurring, and to determine the influence on this prevalence of certain clinical and electrocardiographic parameters, to establish an epidemiological profile of this anomaly.

Methods: In our study, we used the current definition of early repolarization. The study population is represented by 621 athletes participating in the various sports competitions organized in the region of Sétif, having undergone a cardiological examination, at the level of the cardiology service of Setif university hospital center, as part of the establishment of a medical certificate of no contraindication to the practice of the sport. Athletes also benefited from a clinical examination (weight, height, cardiac auscultation, functional signs (angina, palpitation, loss of awareness and dyspnea), palpation of the pulse, and measurement of the blood pressure). The electrocardiograms were collected at rest and away from any sporting activity. And in addition to the analysis of ER (prevalence, notch, slur, amplitude, and topography), criteria for ventricular hypertrophy (Sokolow-Lyon index and Cornell index), heart rate, and right bundle branch block were sought and analyzed.

Results: The ECG was normal in 29.3% of the athletes, while the majority of athletes (66.3%) had adaptative electrocardiographic abnormalities to regular physical training (minimum of 4 h per week) and competition, 4.3% of athletes had abnormal electrocardiographic patterns suggesting underlying heart disease. The prevalence of ER in our athletes according to the new diagnostic criteria is 26.1%, with a clear male predominance. This prevalence increases with age, peaking in the third decade and then declines. The prevalence of ER is higher in bradycardic athletes and those with a Sokolow-Lyon index greater than 35 mm; for the Cornell index, no relationship was found. Moreover, ER is significantly lower in athletes with incomplete right Branch Block. In our series, ER is predominant in the inferior leads (40.7%) than lateral ones (34.6%), and the double location is found in 24.7%. This distribution of topographies is not influenced by age and gender. 31.8% of ER has an amplitude ≥ of 2 mm. 30.9% of ER is associated with ST-segment elevation. Notch is the predominant pattern whatever the topography of ER is (notch, 57.4%; slur, 18.5%; notch+slur, 24.1%); notch predominates in lateral leads (52.3%) while slur is predominant in inferior leads (68.0%).1%); only the notch has a significant relationship with male sex (23.8% vs 5.7%, p<0.001) with bradycardia (41.4% vs 16%, P<0.001) and with physical training. The prevalence of notches and slurs is significantly higher in athletes with a Sokolow-Lyon index greater than 35 mm.

Conclusion: The pattern of ER is frequent in athletes; its prevalence is influenced by age, sex, heart rate, left ventricular hypertrophy, and incomplete right bundle branch block, type of sport, and intensity of the dynamic and static component of sports activity. The inferior topography (considered as a criterion of the high risk of ER) is found the most in our athletes; the notch is the most frequent pattern. It has been found that the two patterns "notch" and "slur", which are the basis of the definition of ER, are not influenced in the same way by the other clinical and electrocardiographic parameters.