Incidental findings of cardiac pauses in a nationwide atrial fibrillation screening trial: Insights from the NORSCREEN trial

Background/Introduction The widespread implementation of long-term ECG monitoring for atrial fibrillation (AF) screening may detect incidental arrhythmias, including significant cardiac pauses. Although the prognostic impact of these pauses is well established in symptomatic patients, their prevalence and clinical determinants in an unselected screening population remain largely unexplored. Purpose To determine the prevalence and identify clinical determinants of cardiac pauses in a large-scale, nationwide AF screening cohort. Methods The ongoing Norwegian AF Self-Screening trial (NORSCREEN) enrolled 50,549 individuals aged ≥65 years with ≥1 additional stroke risk factor and no prior history of AF or anticoagulation therapy. Participants underwent seven days of continuous single-lead ECG monitoring with the ECG247 patch system (Figure 1). All recordings were processed by an automated algorithm; then all arrhythmias were manually verified by a cardiologist. A cardiac pause was defined as an R-R interval of ≥4 seconds, including episodes of sinoatrial (SA) and atrioventricular (AV) block. Results Of 25,264 participants randomized to screening (median age 75 years [IQR 69-78], 46.4% female), 19,723 completed the screening procedure. The median duration of ECG monitoring was 7.2 days [IQR 5.2-7.9]. Incidental cardiac pauses ≥4 seconds were detected in 61 (0.3%) of the 19,723 participants. SA-block was more frequent than AV-block (44 vs 17 participants). The median pause duration was 4.8 seconds [4.4-5.5], and the median number of pauses per participant was 1 [1-3]. The prevalence of cardiac pauses was higher in men than in women (0.4% vs 0.2%; p=0.002) and increased with age (Figure 2). In multivariable logistic regression, male sex (adjusted odds ratio [aOR] 2.98, 95% CI 1.5–5.3) and each five-year increase in age (aOR 1.7, 95% CI 1.3–2.2) remained independent clinical determinants of cardiac pauses. Previous myocardial infarction (aOR 0.5, 95% CI 0.2-1.8), heart failure (aOR 1.2, 95% CI 0.2-9.0), diabetes (aOR 0.6, 95% CI 0.2-1.6), hypertension (aOR 1.0, 95% CI 0.6-1.8) and prior syncope (aOR 2.2, 95% CI 1.0-4.9) were not associated with cardiac pauses. Conclusions In this large-scale, nationwide screening trial, incidental cardiac pauses ≥4 seconds were detected in 0.3% of participants. Cardiac pauses were associated with male sex and older age. The prognostic significance and clinical implications of these findings warrant further investigation.Figure 1Representative ECG tracing from the ECG247 patch-based ECG system illustrating a cardiac pause.Figure 2Prevalence of cardiac pauses ≥4 seconds stratified by age.