First-degree atrioventricular block in children and adolescent athletes

Abstract

Abstract Introduction Intense regular training produces cardiac adaptations that manifests in various changes in the electrocardiogram (ECG), with sinus bradycardia being the most common finding. In adults the PR interval may be elongated and according to different series it can occur in 10–33% of cases, in the contrary in children and adolescent athletes the prevalence categorized by age has not been studied. Purpose Determine the incidence of first-degree atrioventricular (AV) block in a population of children and adolescent athletes in our environment, categorized by age. Methods We performed a cross-sectional study involving children and adolescent athletes between 5 and 16 years old who received a sport medical examination between August 2018 and May 2019. The ECG were obtained and analyzed following international standards, adequate electrode placement was ensured and was interpreted by cardiologists. The PR interval was obtained, considering prolonged if PR>180 milliseconds (ms) in children under 10 years old, PR>190 ms between 10 and 14 and PR>200 ms in those over 14. We categorized our athletes by age into the following four groups corresponding to approximated quartiles: G1 5–8 years, G2 9–11 years, G3 12–13 years, and G4 14–16 years Results A total of 6401 subjects were included, mean age was 11.2±2.9 years, 93.7% were male, soccer players (97.2%) and Caucasian (99.2%). They trained a mean of 5.4±2.3 hours a week. 11.4% of the patients had mild (50–59 bpm) or moderate (40–49 bpm) bradycardia, but none had severe bradycardia (<40 bpm). Sixty-one patients (0.96%) had 1st degree AV block and 19 (0.30%) had a PR interval at higher limit of normality. When stratified by age groups, the prevalence of 1st degree AV block was higher in the second quartile (Table 1). We did not find cases of Wenckebach or high-grade AV block (Mobitz II or 3rd degree AV block). Conclusions In children and adolescent athletes, the incidence of first-degree AV blockade is low (around 1%) and significantly lower than what is reported in adults. This may be due to a lower vagal tone in this population. If detected it may prompt clinicians to pursue further investigation given the low proportion of 1st degree AV block in children and adolescent athletes. Figure 1. Sixteen year old patient ECG Funding Acknowledgement Type of funding source: None