Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction The 12-lead resting electrocardiogram is a useful tool for diagnosing pathological conditions in athletes. The prevalence of electrocardiographic abnormalities in Brazilian soccer players are unknown. Purpose To describe the prevalence of abnormal electrocardiographic findings in young Brazilian soccer players based on the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Methods Continuous variables were displayed as mean and standard deviation or median and interquartile range, while prevalence’s with 95% confidence intervals, and stratified by race. Intra-group differences were estimated by linear models or binomial and multinomial logistic regressions. Type I error was set to set a at 0.05. An additional margin of 0.025 was considered at the discretion of the statistician conditioned to the quality of the model. All analysis were running in Stata version 16.0.0. Results 2,581 young Brazilian soccer players from 27 clubs (mainly first division), aged 15-35 years (median: 18 years) were evaluated. 1,268 (49.1%) were Caucasians, 796 (30.8%) Mixed-Race (MR) and 517 (20.1%) Afro-Brazilians (AB). T-wave inversion (TWI) in the inferior leads (3.0%), high lateral leads (DI/aVL) (0.6%), V5 (2.3%), V6 (1.8%), and V5-V6 (1.7%) were present. Six Caucasians (0.5%) presented TWI in V1-V4. Prolonged corrected QT interval (QTc) (0.5%), QRS ≥140 ms (0.2%), "pathological" anterior Q waves (0.2%), lateral ST-segment depression (0.07%), premature ventricular contractions (0.5%), Mobitz type II atrioventricular block (0.03%), and a Wolff-Parkinson-White pattern (0.04%) were also observed. There were no athletes with short QTc interval, epsilon waves, profound sinus bradycardia (<30 beats per minute), complete left bundle branch block, third-degree atrioventricular block, or Brugada pattern (1, 2 or 3). Overall, 111/2,581 (4.3%) soccer players had electrocardiographic changes considered to be abnormal (4.4% in Caucasians, 4.5% in MR and 6.4% in AB). There was no difference between the abnormal findings among races, except for the prevalence of TWI in V6, which was higher in AB compared to Caucasians (3.1% versus 1.2%, respectively; P = 0.01). Conclusion To the best of our knowledge, this is the first large electrocardiographic cohort of Brazilian young soccer players to be described. In this sample, we evidence a prevalence <5% of abnormal findings according to the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Additional evaluation in all these cases is indicated.

Funding Acknowledgements Type of funding sources: None. Introduction Black athletes may be more likely to have uncommon electrocardiogram findings than white athletes. The prevalence of abnormal electrocardiographic findings in elite Brazilian football players (EBFP) of different ethnicities is unknown. Purpose To compare the prevalence of these changes and their correlation with the echocardiogram and cardiac magnetic resonance (CMR) in Caucasian, Mixed-race (MR), and Afro-Brazilian (AB) EBFP. Methods A multicenter cross-sectional descriptive study was conducted with exams performed on EBFP as a pre-participation assessment from February 18, 2002, through October 20, 2022. Results 4,363 EBFP from 51 professional clubs (from all five regions of Brazil; 15 states, and 21 cities), aged 15-35 years (median: 19 years; IQR: 16-23) were evaluated. 2,027 were Caucasians, 1,324 were MRs, and 1,012 were ABs. T-wave inversion (TWI) in leads II and aVF (4.2% vs. 2.3%), V5 (4.0% vs. 1.7%), and in V5-V6 (3.0% vs. 1.4%) was more common in AB than in Caucasian players, respectively (P = 0.002 for all comparisons). In addition, AB demonstrated a significantly greater prevalence of inferolateral TWI (2.3%) than Caucasian (1.1%), and MR (1.3%) EBFP, respectively. TWI in leads V1-V3 in Caucasians or MRs >16 years was present in 0.9% (30/3,351). PR interval ≥400 ms was observed in one Caucasian and in one AB athlete. The Wolff-Parkinson-White pattern was identified in two Caucasians, and a suggestive case of a type 2 Brugada Pattern in one Caucasian. Overall, 208 (4.8%) EBFP had electrocardiographic changes considered to be abnormal (4.5% in Caucasians, 4.8% in MRs, and 5.2% in ABs). Of these, 150/208 (72.1%) underwent an echocardiogram. Isolated inferior TWI was not associated with echocardiographic abnormalities (n = 25), similar to persistent juvenile TWI patterns (in Caucasians or MRs). However, TWI in inferolateral leads was associated with 10.5% echocardiographic abnormalities (4/38). Of these, 75% (3/4) had abnormal CMR findings: one AB with hypertrophic cardiomyopathy (CMP), and two Caucasians with non-compaction CMP; one Caucasian with an abnormal echocardiogram demonstrated normal CMR, suggesting "athlete's heart". Finally, one AB had normal echocardiogram results, but the CRM showed a finding compatible with apical hypertrophic CMP. Conclusion In this large cohort of EBFP, approximately 5% of the electrocardiographic findings were considered abnormal. In those with inferolateral TWI, the use of CMR may indicate the presence of potentially malignant cardiac disease, even with normal echocardiographic findings. AB ethnicity was associated with a higher prevalence of TWI in the inferior and/or lateral leads in comparison to Caucasian or MR ethnicities.

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): CNPq, CAPES, FIPE-HCPA. Introduction The 12-lead electrocardiogram (ECG-12) is a useful tool in the assessment of athletes. The prevalence of normal electrocardiographic findings in elite Brazilian football players (EBFP) of different ethnicities is not well described. Purpose To compare the prevalence of normal ECG-12 findings in Caucasian, Mixed-race (MR), and Afro-Brazilian (AB) EBFP. Methods A multicenter cross-sectional descriptive study was conducted with exams performed on EBFP as a pre-participation assessment from February 18, 2002, through October 20, 2022. Results 4,363 EBFP from 51 professional clubs (from all five regions of Brazil; 15 states, and 21 cities), aged 15-35 years (median: 19 years; IQR: 16-23) were evaluated. 2,027 were Caucasians, 1,324 were MRs, and 1,012 were ABs. In general, we recorded 4,155 ECG-12 with normal variations (95.2%). Positive Sokolow-Lyon criteria for left ventricular hypertrophy was more prevalent in ABs (41.8%) than in Caucasians (33.4%), or MRs (32.7%). The prevalence of early repolarization in ABs (41.5%) was higher than in Caucasians (34.6%), or MRs (35.5%). The PR interval was longer in ABs (157.1 ms) than in Caucasians (151.4 ms), or MRs (153.3 ms), and the first-degree atrioventricular block was more frequent in ABs compared to MRs (4.2% vs. 2.3%, respectively). On the other hand, Caucasians had a higher prevalence of incomplete right bundle branch block (14.2%) than MRs (11.2%), or ABs (9.7%). In our sample, only three EBFP showed second-degree atrioventricular block Mobitz type I (0.07%; one Caucasian and two AB athletes). Conclusions This is the first large study to compare the prevalence of ECG-12 findings in EBFP from different ethnic groups. Those of AB origin have a significantly higher prevalence of ECG-12 findings compatible with the athlete's heart than Caucasians and MRs.

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction The 12-lead electrocardiogram (ECG-12) is a useful tool in the assessment of athletes, and it may present findings compatible with physiological adaptations to regular exercise. ECG-12 findings in Brazilian soccer players are unknown. Purpose To describe the prevalence of physiological ECG-12 findings in young Brazilian soccer players based on the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Methods Continuous variables were displayed as mean and standard deviation or median and interquartile range, while prevalence’s with 95% confidence intervals, and stratified by race. Intra-group differences were estimated by linear models or binomial and multinomial logistic regressions. Type I error was set to set a at 0.05. An additional margin of 0.025 was considered at the discretion of the statistician conditioned to the quality of the model. All analysis were running in Stata version 16.0.0. Results 2,581 athletes from 27 clubs (mainly first division), aged 15-35 years (median: 18 years) were evaluated. 1,268 (49.1%) were Caucasians, 796 (30.8%) Mixed-race (MR) and 517 (20.1%) Afro-Brazilians (AB). In this sample from across the country, we identified the following findings and its respective prevalence: sinus bradycardia (50%), ectopic atrial rhythm (1.4%), junctional rhythm (0.3%), incomplete right bundle branch block (23.7%), first-degree atrioventricular (AV) block (3.0%), Mobitz type I AV block (0.1%), and increase QRS voltage for left or right ventricular hypertrophy (35.2% and 17.3%, respectively). The mean PR interval was 153.9±28.7 ms, corrected QT interval 399.2±28.0 ms, and QRS duration 96.0±14.0 ms. ST elevation followed by T-wave inversion in leads V1–V4 was identified in 11/517 (2.1%) of AB athletes. Early repolarization was present in 828 athletes (32.1%), being more prevalent in AB when compared to MR and Caucasians (P = 0.003). Likewise, AB had a greater PR interval in comparison to MR and Caucasians (P <0.001 and P = 0.007, respectively). On the other hand, Caucasians had a significant longer QRS duration compared to AB. For all remaining variables there was no difference among races. Conclusions To the best of our knowledge, this is the first large study to describe the prevalence of physiological electrocardiographic finding in young Brazilian soccer players, according to "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Future studies comparing the frequency of these findings with the prevalence observed in other cohorts are welcome.

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction Black athletes may present some peculiarities in the resting 12-lead electrocardiogram, such as T-wave inversion (TWI) confined to V1-V4 preceded by ST-segment and J-point elevation (‘domed’ ST-elevation and TWI in V1-V4), the so-called Afro-Caribbean pattern, a benign variant of the athlete's heart according to the "2017 International criteria for electrocardiographic interpretation in athletes". However, the prevalence of these findings in young Afro-Brazilian (AB) soccer players is unknown. Purpose To compare the prevalence of ‘domed’ ST-elevation and TWI in V1-V4 among young AB soccer players with Ghanaians black soccer players. Methods We sought to do this analysis visually, as the data from AB soccer players were as raw data; and those from Ghana’s were else aggregated. A forest plot with the point estimate and confidence intervals at 95% was built and, whenever any region from the lower limit up to the upper limit of the confidence interval of a given variable interpolate to the other, no differences could be claimed. The forest plot was built at R v. 4.1.2 using the package "metafor". Results Data from 517 young AB soccer players (mean age: 20 years) and 159 young black soccer players from Ghana (mean age: 19 years) were evaluated and compared. The average height and weight were similar (177.2 cm and 70.7 kg for AB, and 175.2 cm and 68.4kg for Ghanaians players). Ghanaians had a significant higher prevalence of ‘domed’ ST-elevation and TWI in V1-V4 than AB (16.7%; 95% CI, 13.1 to 25.8 versus 2.1%; 95% CI, 1.2 to 3.9, respectively). Conclusion To the best of our knowledge, this is the first study to describe the low prevalence of the ‘domed’ ST-elevation combined with TWI in V1-V4 in young AB soccer players. Interestingly, when compared to Ghanaians young soccer players (all of them black African individuals), AB athletes presented a significant lower frequency of this finding (16.7% versus 2.1%). Finally, we hypothesize that ‘domed’ ST-elevation and TWI in V1-V4 seen in African athletes appears to become less prevalent in the generations after the time of migration from Africa to Brazil. Whether this is due to environmental or genetic changes, further studies should clarify.