Electrocardiographic diversity in football players: how distinct ethnic patterns shape athletes’ hearts

In this exclusive interview, we speak with Filipe Ferrari (F.F.) and Ricardo Stein (R.S.), two of Brazil's leading researchers in sports cardiology and authors of four landmark studies examining electrocardiographic (ECG) patterns in Brazilian soccer players 1-4 (Figure 1). Their work sheds light on the complex interplay between ethnicity, athletic training, and cardio-vascular screening. With data collected over two decades from more than 6000 athletes, their research provides critical insights that challenge established norms and contribute to evolving international guidelines. ➢ You've now published a series of studies across four major journals, 1-4 examining over 6000 Brazilian footballers' ECGs. What inspired you to take on such a large, long-term investigation? F.F. and R.S.: We started this research due to the clear lack of ECG data on Brazilian athletes, especially Mixed-race players who are under-represented in current athlete ECG guidelines. 5 To address this, we partnered with football clubs across the country to build a robust and diverse dataset. In addition to ECGs, we collected imaging data to enhance interpretation and understanding structural correlates. Over time, this comprehensive database allowed us to conduct multiple analyses, resulting in several publications that help refine ECG interpretation in Brazil and contribute valuable insights to the global sports cardiology community. ➢ In one of the papers, 1 you show that 97% of ECGs were normal, even in this ethnically diverse, highly trained population. Did this low prevalence of abnormalities surprise you? And how do you think these challenges or reinforces current preparticipation screening practices? F.F. and R.S.: The low prevalence of abnormal ECGs (3%) was not entirely surprising, as we had initially estimated around 5%. Most players were young (aged 15 to 25), and in one of our studies, 4 we found that abnormalities tend to become more common with age, especially between 26 and 35 years, which helps explain our overall results. Compared to an African cohort of male soccer players (23%), 6 our lower rate may be partially attributed to Brazil's high genetic admixture, which tends to dilute distinct ECG patterns seen in more homogeneous populations. These findings support the effectiveness of current international ECG interpretation criteria, 5 which, when applied correctly, reduce false posi-tives and still identify athletes at risk-even in diverse populations. ➢ Your work consistently shows that Black athletes have more training-related ECG changes, but the 'African/Afro-Caribbean' pattern is much rarer in Brazilian players than in African or European cohorts. Do you think this is mostly genetic (due to Brazil's high admixture), environmental , or something else entirely? F.F. and R.S.: Yes, we believe genetics play a key role, particularly Brazil's extensive ethnic admixture, which contributes to greater diversity and a lower prevalence of the typical 'African/Afro-Caribbean' ECG pattern. 3 It's also important to note that the category of 'Black athletes' in Brazil is heterogeneous. Individuals identifying as Black or Mixed-race often have diverse ancestral backgrounds, which likely influences the expression of training-related ECG changes compared to more genetically homogeneous African or Afro-Caribbean populations. ➢ In another publication, 2 you meticulously classified early repolarization into seven distinct morphologies. Was there one pattern that clinicians should pay closer attention to, especially in athletes of mixed or black ethnicity? F.F. and R.S.: In our sample of 6353 players, early repolarization (ER) was common (40%), especially among Black (48%) and Mixed-race (41%) athletes. The classic J-wave with ascending ST-segment-typically benign and training-related-was the most frequent morphology. Patterns considered higher risk in the general population, such as horizontal ST-segment or inferolateral J-waves morphologies, were rare. During a mean 4-year follow-up, no sudden cardiac deaths occurred. These results suggest that ER, especially in athletes, is likely a benign finding when interpreted in the appropriate clinical context. ➢ You've emphasized the underrepresentation of mixed-race athletes in current ECG interpretation guideline.