Several studies over the past three decades have characterized the electrical and structural cardiac changes that occur in large athletic cohorts.^1-3 Most studies have focused only on White (Caucasian) or Black (African/Caribbean) athletes, highlighting important differences between these groups.^1,2 These data have helped inform the international recommendations for interpretation of electrocardiograms (ECGs) among athletes.⁴ The most notable repolarization differences include T-wave inversion (TWI) in V1-V4 preceded by J-point elevation and a convex ST-segment, that is considered a normal variant among Black athletes, but would warrant further evaluation for underlying cardiomyopathy among White athletes.

The demographic landscape for athletes consists of a growing population of mixed-race individuals in whom one parent is Black and the other parent is White. Whether the electrical and structural cardiac features of the mixed-race athlete is more consistent with those of White or Black athletes is unknown.

In our letter, published earlier this year in Circulation, we examined, cross-sectionally, the ECGs and echocardiograms in 1,000 healthy, mixed-race male soccer players and compared those of 1,000 White and 1,000 Black male soccer players.⁵

The top three takeaways from this study are as follows:

1. Mixed-race athletes have a higher prevalence of T-wave inversion (8.6%) compared with White athletes (2.3%) but lower than in Black athletes (12.6%). TWI occurred predominantly in the anterior leads with inferior and/or lateral TWI being rare.
2. Mixed-race athletes demonstrate greater left ventricular wall thickness than White athletes but less than Black athletes, even after indexing for body surface area. In absolute terms, left ventricular hypertrophy (by wall thickness) >12mm was present in 5.9% mixed-race athletes, though was higher among Black athletes (7.1%), and lowest in White athletes (1.3%).
3. Mixed-race athletes have larger left ventricular cavities than Black athletes though smaller than White athletes. These differences became more pronounced when indexed for body surface area. Of mixed-race athletes, 4.4% demonstrated a left ventricular end diastolic dimension >58 mm, compared with 5.9% of White athletes and 3.2% of Black athletes.

These data add to our growing understanding of the impact of race on the athlete's heart. However, it is important to recognize that identifying athletes as Black, White, or mixed-race may still be rudimentary considering the diverse racial heterogeneity of the sporting world. Categorizing athletes by race, without acknowledging environmental and social determinants of health is particularly problematic when assessing outcomes. A more accurate classification using genetic ancestry would be less ambiguous and future studies should endeavor to utilize genomics and genome-wide analyses to understand the geographic origins of an athlete's ancestors.⁶ Genetic ancestry through population-based studies may help explain variation in ECGs and echocardiograms between and within racial groups. Importantly, these analyses may identify genetic variants that increase the likelihood of benign repolarization changes and left ventricular hypertrophy, as well as genetic variants that lead to pathological cardiovascular remodelling and increase the risk of sudden death. In the meantime, our data suggest that mixed-race athletes demonstrate electrical and structural cardiac adaptations that are more like Black athletes than White athletes. Care should be taken to acknowledge such physiological adaptations and avoid unnecessary further evaluation in this group.

References

1. Sheikh N, Papadakis M, Carre F, et al. Cardiac adaptation to exercise in adolescent athletes of African ethnicity: an emergent elite athletic population. Br J Sports Med 2013;47:585–92.
2. Papadakis M, Carre F, Kervio G, et al. The prevalence, distribution, and clinical outcomes of electrocardiographic repolarization patterns in male athletes of African/Afro-Caribbean origin. Eur Heart J 2011;32:2304–13.
3. Rawlins J, Carre F, Kervio G, et al. Ethnic differences in physiological cardiac adaptation to intense physical exercise in highly trained female athletes. Circulation 2010;121:1078–85.
4. Sharma S, Drezner JA, Baggish A, et al. International recommendations for electrocardiographic interpretation in athletes. J Am Coll Cardiol 2017;69:1057–75.
5. Malhotra A, Oxborough D, Rao P, et al. Defining the normal spectrum of electrocardiographic and left ventricular adaptations in mixed-race male adolescent soccer players. Circulation 2021;143:94–96.
6. Borrell LN, Elhawary JR, Fuentes-Afflick E, et al. Race and genetic ancestry in medicine - a time for reckoning with racism. N Engl J Med 2021;384:474–80.

Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Sports and Exercise Cardiology, Genetic Arrhythmic Conditions

Keywords: Sports, Athletes, Hypertrophy, Left Ventricular, Soccer, Body Surface Area, Genome-Wide Association Study, African Americans, Prevalence, Social Determinants of Health, Adaptation, Physiological, Genomics, Heart Ventricles, Electrocardiography, Cardiomyopathies

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