The Athlete’s ECG

Sudden cardiac death (SCD) is the leading non-traumatic cause of mortality in athletes under 35, most often due to inherited cardiomyopathies or primary electrical disorders that may remain silent until a fatal event. The 12-lead electrocardiogram (ECG) is the most accessible and cost-effective screening tool, yet its early use was hampered by poor specificity and high false-positive rates, mainly due to non-standardized interpretation and limited awareness of physiological adaptations. Recent studies have led to international guidelines that classify findings as physiological, borderline, or pathological, thereby reducing unnecessary investigations while preserving sensitivity for relevant conditions. Physiological variants are shaped by age, sex, ethnicity, sport type, and training load. Borderline findings demand careful clinical judgment, while certain abnormalities – including lateral T-wave inversions, ST-segment depression, pathological Q waves, ventricular arrhythmias, and prolonged QTc intervals – are consistently pathological and mandate further evaluation. Notably, ECG changes may precede structural abnormalities by years, highlighting the importance of longitudinal follow-up in athletes with suspicious findings. Although resting ECG cannot identify all causes of SCD – particularly congenital coronary anomalies or ischemic disease in older athletes – it remains an indispensable and validated cornerstone of preparticipation cardiovascular screening, contributing significantly to the prevention of SCD in sport.