Original Article Prevalence and predictors of electrocardiogram abnormalities among athletes Nurul Atiqah Abu Bakar 1 , Nazar Luqman 2 , Essam Shaaban 3 and Hanif Abdul Rahman 1 Abstract Background: Existing evidence, predominantly from Western countries, has demonstrated that athletes’ hearts under- go structural, physiological, and electrical changes, leading to abnormal electrocardiogram readings that are said to be training-related. Athletes with non-training-related electrocardiographic abnormalities risk developing sudden cardiac death. The lack of studies on this issue in the Asian population warrants further exploration. Therefore, the aim of this study was to estimate the prevalence and predictive factors contributing to electrocardiogram abnormalities among athletes in Brunei. Methods: A descriptive cross-sectional study was conducted on 100 athletes (median age 25.2 years) in 10 sporting disciplines, whose electrocardiogram readings and essential information was obtained. Results: The prevalence of an abnormal electrocardiogram was 52% (95% confidence interval: 42.0%–62.0%), com- prising training-related changes in 49% (95% confidence interval: 39.0%–59.0%) and non-training-related changes in 3% (95% confidence interval: 0.4%–6.4%). Athletes with a higher body mass index were 3.3-times (95% confidence interval: 1.47–9.58) more likely to have abnormal electrocardiogram readings. Athletes <25-years old (odds ratio ¼ 0.25, 95% confidence interval: 0.07–0.81) and those who trained with low dynamic intensity (odds ratio ¼ 0.33, 95% confidence interval: 0.12–0.93) were significantly less likely to have electrocardiogram abnormalities. Conclusions: This is the first study reporting abnormal electrocardiograms among athletes in Brunei, which provides important information to relevant agencies involved in the preparation of Asian athletes for domestic or international competitions, particularly those with a higher body mass index and low dynamic training intensity. Keywords Age factors, Body mass index, Brunei, Cardiomegaly, exercise-induced, Electrocardiography, Sports Introduction Many studies have demonstrated that athletes undergo structural heart changes, 1–7 mainly left ventricular enlargement. 1–6 The way the ventricle enlarges differs between endurance athletes and strength athletes. In endurance athletes, the increase in chamber size is greater than the increase in wall thickness. The oppo- site is found in strength athletes. 3 As for the left atrium, a study found that 24.3% of athletes had a mild increase in left atrial volume index. 7 However, there are limited data on the right atrium and ventricle. These structural changes are accompanied by physio- logical changes to adapt to athletic training. The higher the intensity of exercise (endurance sports), the greater the need for oxygen. To deliver sufficient oxygen for endurance sports, there is an increase in pulmonary oxygen uptake, which in the long-term, increases maximal oxygen uptake. On the other hand, strength 1 PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Brunei 2 Department of Cardiology, Raja Isteri Pengiran Anak Saleha Hospital, Ministry of Health, Brunei 3 Sports Medicine and Research Centre, Brunei Corresponding author: Hanif Abdul Rahman, PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, Brunei-Muara BE 1410, Brunei Darussalam. Email: hanif.rahman@ubd.edu.bn Asian Cardiovascular & Thoracic Annals 0(0) 1–5 ! The Author(s) 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0218492318807533 journals.sagepub.com/home/aan