Defining the Normal Spectrum of Electrocardiographic and Left Ventricular Adaptations in Mixed-Race Male Adolescent Soccer Players

Background: Cardiovascular adaptation in adolescent athletes is significantly understudied compared with adult athletes. Among adult and adolescent black athletes (African or Afro Caribbean origin) electrical and left ventricular adaptation may overlap with morphologically mild hypertrophic cardiomyopathy (HCM). Adolescent mixed-race athletes, where one parent is white and the other is black, are the fastest growing ethnic group of athletes in the Western world, yet the electrical and structural manifestations in this cohort have never been described. The aim of our study was to examine the similarities and differences in the spectrum of ECG changes and left ventricular dimensions in a large cohort of healthy mixed-race adolescent soccer players compared with identical cohorts of white and black adolescent athletes. Methodology: 3000 healthy male soccer players (mean age 16.4±1.3 years) including an equal proportion of mixed-race, white and black athletes were evaluated with an ECG and echocardiogram. Results: Mixed-race athletes demonstrated a higher prevalence of T-wave inversion (8.6% vs. 2.3%; p<0.0001), a greater magnitude of left ventricular (LV) wall thickness (9.8 vs 9.2 mm; p<0.0001) and a smaller LV cavity (51.1 vs. 52.4 mm; p<0.0001) compared with white athletes. Mixed-race athletes demonstrated a lower prevalence of T-wave inversion (8.8% vs 12.6%; p<0.0001) and a smaller magnitude of LV wall thickness (9.8 vs. 10.1 mm; p<0.0001) compared with black athletes but revealed a larger LV cavity (51.1 vs. 50.6mm; p=0.005). 7% of mixed-race athletes either had a left ventricular wall thickness >12mm or inferior/ lateral T-wave inversion but did not reveal any overt phenotypic features of HCM during further investigation, compared with <2% white athletes. Conclusions: Mixed-race adolescent athletes show a higher prevalence of T-wave inversion and a greater magnitude of LV wall thickness compared with white athletes, but to a lesser extent than in black athletes. As with black athletes, a small but significant proportion of mixed-race athletes reveal electrical and structural features that would raise suspicion of HCM in a white athlete. Such variations among mixed-race athletes should be considered when evaluating this fast-growing ethnic group.