Incidental findings of ventricular tachycardia 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 uncover incidental arrhythmias, most notably non-sustained ventricular tachycardia (NSVT). While the prognostic impact of NSVT is well-established in patients with overt cardiovascular disease, its prevalence and clinical determinants in an unselected screening population remain largely unexplored.

Purpose

To determine the prevalence and clinical determinants of NSVT 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 7 days of continuous single-lead ECG monitoring using the ECG247 patch system (Figure 1). All recordings were processed by an automated algorithm, followed by manual verification by a cardiologist. NSVT was defined as ≥4 consecutive ventricular beats at a rate ≥100 bpm, lasting <30 seconds.

Results

Of 25,264 participants randomized to screening (median age 75 years [IQR 69-78], 46.4% female), 19,723 completed the screening procedure. Median ECG monitoring duration was 7.2 days [IQR 5.2-7.9], with 52.0% monitored for ≥7 days. Incidental NSVT was detected in 824 (4.2%), with a median episode duration of 3 seconds [IQR 2-5]. The prevalence of NSVT was higher in men than in women (5.9% vs 2.1%, p<0.001), with no significant age difference between individuals with and without NSVT. Participants with NSVT more frequently had prior myocardial infarction (12.3% vs 8.2%, p<0.001), heart failure (3.1% vs. 1.7%, p<0.001), and current smoking (8.0% vs 5.8%, p<0.001). No significant differences were observed for hypertension (65.5% vs 67.1%, p=0.32), chronic obstructive pulmonary disease (4.8% vs 4.6%, p=0.76), or diabetes (11.3% vs 13.4%, p=0.08). In multivariable logistic regression, male sex (adjusted odds ratio [aOR] 2.9, 95% CI 2.4–3.4), heart failure (aOR 1.6, 95% CI 1.1–2.6), and current smoking (aOR 1.4, 95% CI 1.0–1.9) independently predicted the presence of NSVT (Figure 2).

Conclusions

In this large-scale, nationwide screening trial, incidental NSVT was detected in 4.2% of participants. NSVT was associated with male sex, heart failure and current smoking. The prognostic significance and clinical implications of these findings warrant further investigation.

Figure 1:A) Representative ECG tracing from the ECG247 patch-based ECG system showing a non-sustained ventricular tachycardia (NSVT). B) Prevalence of NSVT stratified by age.

Figure 2: Association between baseline characteristics and the probability of non-sustained ventricular tachycardia (NSVT).Figure 1Figure 2