ABSTRACT
INTRODUCTION: Although it is wellknown that longer electrocardiographic (ECG) monitoring allows for detection of paroxysmal silent atrial fibrillation (SAF), it is still unknown how long the ECG monitoring should last to increase the probability of SAF diagnosis. OBJECTIVES: Our aim was to analyze ECG acquisition parameters and timing to detect SAF during the Noninvasive Monitoring for Early Detection of Atrial Fibrillation study. PATIENTS AND METHODS: The protocol assumed up to 30 days of ECG telemonitoring of each participant in order to reveal AF / atrial flutter (AFL) episodes lasting at least 30 seconds. SAF was defined as AF detected and confirmed by cardiologists in asymptomatic individuals. The ECG signal analysis was based on the results of 2974 participants (98.67%). AF/AFL episodes were registered and confirmed by cardiologists in 515 individuals, that is, 75.7% of all patients (n = 680) in whom AF/AFL diagnosis was established. RESULTS: The median monitoring time to detect the first SAF episode was 6 days (interquartile range [IQR], 1-13). Fifty percent of the patients with this type of arrhythmia were identified by 6th day (IQR, 1-13) of the monitoring, and 75% by the 13th day of the study. Paroxysmal AF was registered on average on 4th day (IQR, 1-10). CONCLUSIONS: The ECG monitoring time to detect the first episode of SAF in at least 75% of patients at risk of this arrhythmia was 14 days. Detection of 1 patient with de novo AF, SAF, or de novo SAF, required monitoring of, respectively, 17, 11, and 23 patients.