Prevalence and relation to training of electrocardiographic findings in Caucasian children and adolescents 8- to 18-year-old practicing competitive sport

Abstract

Aims: Training frequently induces electrocardiographic (ECG) changes that mimic heart diseases, requiring specific criteria for interpretation. Paediatric athletes represent a unique population as training-induced changes and those due to sexual maturation interact, and specific criteria may be needed. We aimed to assess the prevalence and its relation to training of ECG abnormalities in young athletes aged 8-18 years.

Methods and results: We included 2458 young apparently healthy Caucasian athletes undergoing pre-participation screening. Electrocardiographic abnormalities were classified according to the 2017 International criteria (IC) by adding fragmented QRS and low QRS voltages in limb leads. A subgroup analysis was conducted to test the differences according to a 12-year-old age cut-off, the threshold for IC application. Common (>5%) findings included only mild sinus bradycardia (55-60 b.p.m.), early repolarization, incomplete right bundle branch block, voltage criteria for either left or right ventricular hypertrophy and T-wave inversion in V1-V3 before the age of 12. A heart rate of 50-55 b.p.m., first-degree atrioventricular block, right-axis deviation, and T-wave inversion in V1-V3 in athletes 12- to 16-year-old were uncommon (1-5%) and their prevalence was modulated by age, gender, and/or training status. All other ECG findings were rare (<1%). Ten (0.4%) athletes received an at-risk cardiovascular disease diagnosis including 6 with rare and 1 with uncommon ECG abnormalities: 3 of 7 were classified as normal by IC.

Conclusion: Paediatric athletes exhibit less prominent ECG changes than their adult counterparts, requiring specific criteria. The significance of certain ECG patterns should be evaluated considering age, sex, and training level.

Keywords: Paediatrics; Pre-participation screening; Sports cardiology; Sudden cardiac death.

Graphical Abstract

Figure 1

CONSORT-style diagram illustrating the structure of the cohort investigations. The diagram shows the recruitment and clinical work-up of 2458 athletes. Cardiac diagnosis was established in 10 athletes (0.4%). CMR, cardiac magnetic resonance; CT, computed tomography; ECG, electrocardiogram; ES, electrophysiological study; ET, exercise testing; P/E, physical examination.

Figure 2

Histograms showing the prevalence of negative T-wave in V1–V3 depending on age.

Figure 3

Heart rate (HR) and PR interval duration: distribution and age-specific trends. Left panels: Histograms showing the frequency distribution of HR (top) and PR interval (bottom) in the two age groups aged 8–11 years and adolescents aged 12–18 years. Right panels: Boxplots illustrating age-specific trends for HR (top) and PR interval duration (bottom) from 8 to 18 years. Dashed lines indicate proposed reference limits.

Figure 4

Age-specific prevalence of electrocardiographic findings in the paediatric population. The graph displays the percentage of individuals with electrocardiographic findings with a frequency ≥1% across ages 8–18 years. LVH, left ventricular hypertrophy; RVH, right ventricular hypertrophy; iRRR, incomplete right bundle branch block; ER, early repolarization; SB, sinus bradycardia with subgroups based on heart rate (SB <60, SB 50–55, SB <55); EAR, ectopic atrial rhythm; IAVB, first-degree atrioventricular block. For variables showing an age-dependent prevalence based on the regression analysis (Table 3), dashed red vertical lines indicate the transition between individuals under and over 12 years of age.