Incremental diagnostic value of 24-hour Holter monitoring during training in elite athlete preparticipation screening.

Background: Preparticipation cardiovascular evaluation (PPE) is widely recommended to reduce the risk of sudden cardiac events in athletes; however, the optimal screening protocol remains debated. Although resting ECG and echocardiography are commonly used, intermittent arrhythmias may remain undetected. Objective: To assess whether the addition of 24-hour ambulatory ECG (Holter) monitoring, including during sleep and training, increases the detection of potentially pathological cardiovascular findings. Design and settings: This observational cross-sectional study included athletes (aged 14-42 years) from a Spanish elite multisport professional club undergoing pre-season PPE during the 2023-2024. All athletes completed a standardised evaluation comprising medical history and physical examination, resting 12-lead ECG, transthoracic echocardiography and 24-hour wireless Holter monitoring performed during daily activities including at least one training session. Detection rates of potentially pathological findings were compared across screening test combinations. Participants: Of 343 athletes recruited, 299 (79.6% male; mean age 22 years) were included in the final analysis. Results: Potentially pathological findings prompting further evaluation were identified in 34 athletes (11.3%). The addition of any single test to medical history and physical examination significantly increased detection rates. Holter monitoring identified more intermittent arrhythmic events, particularly during exercise or sleep, whereas resting ECG more frequently detected repolarisation abnormalities. Echocardiography primarily contributed to the identification of structural abnormalities. Following a comprehensive evaluation, only one athlete was disqualified from competition. Conclusions: In elite athletes, integrating Holter monitoring into PPE improved the detection of intermittent arrhythmias that may be missed by a resting ECG alone, and providing complementary diagnostic information and representing a useful adjunct to echocardiography in comprehensive cardiovascular screening strategies, particularly in selected high-risk athletic populations. Future longitudinal studies are warranted to determine the clinical significance of these findings.