Atrial fibrillation detection in endurance athletes vs non-athletes: Positive predictive value and burden estimation using implantable cardiac monitors

Background: Implantable cardiac monitors (ICMs) enable continuous arrhythmia detection and quantification of atrial fibrillation (AF) burden. However, the influence of an athletic lifestyle on the positive predictive value (PPV) of ICM-detected AF episodes, and the accuracy of automated AF burden estimation, remain uncertain. Objective: This study aimed to compare the PPV of ICM-detected AF episodes between athletes and non-athletes with known AF, and to evaluate the accuracy of automatic AF burden estimation. Methods: During a 4-week pre-randomization phase of 2 randomized trials, 3041 AF episodes lasting ≥30 seconds were detected by ICMs in 32 endurance athletes and 159 non-athletes with non-permanent AF, totaling 4202 monitored days. All episodes were manually adjudicated to determine true AF. PPV increased significantly with longer episode duration, reaching 0.89 (95% CI 0.83-0.94) for episodes >60 minutes vs 0.42 (95% CI 0.35-0.48) for episodes <6 minutes. Findings were consistent across groups. Correlation between automatic and validated AF burden was 0.67 (95% CI 0.56-0.77), improving to 0.85 (95% CI 0.80-0.92) after excluding episodes shorter than 6 minutes. Conclusion: The PPV of ICM-detected AF episodes is similar in athletes and non-athletes. Longer AF episode duration enhances accuracy, and excluding short episodes improves automated AF burden estimation. ICMs may serve as good alternatives for AF monitoring also in athletic subpopulations.