Medical Evaluation of Athletes: Electrocardiogram

Abstract

Sudden cardiac death (SCD) is the leading cause of sudden death in athletes during sports and exercise, and electrocardiogram (ECG) abnormalities are present in the majority of conditions associated with SCD. Whether used for screening or diagnostic purposes, proper ECG interpretation is a fundamental skill for physicians responsible for the cardiovascular care of athletes. Contemporary athlete-specific ECG interpretation standards aim to distinguish physiologic cardiac adaptations from findings that may represent a pathologic disorder. This chapter reviews both physiologic and pathologic findings on an athlete’s ECG based on the latest International Criteria for ECG interpretation in athletes. Common training-related ECG changes due to enlarged cardiac chamber size and increased vagal tone include sinus bradycardia, sinus arrhythmia, voltage criteria for left ventricular hypertrophy, incomplete right bundle branch block, and early repolarization. ECG abnormalities unrelated to athletic conditioning and warranting further evaluation include T wave inversions, ST-segment depression, pathologic Q waves, ventricular pre-excitation, and a prolonged QT interval. Proper secondary testing of ECG abnormalities is critical to exclude the presence of pathologic cardiac disease. Athletes with lateral or inferolateral T wave inversion should undergo cardiac magnetic resonance imaging when available. For athletes with a markedly abnormal ECG without evidence of structural disease on initial cardiac imaging, serial evaluation is recommended to monitor for delayed phenotypic expression of cardiomyopathy.