Smartwatch-detected arrhythmias : characteristics, management and short-term outcomes - The CONNECT study -

Background

Smartwatches are increasingly used and some can record single-lead ECGs. Although diagnostic performance is well established, the clinical profile, downstream care pathways and outcomes of patients prompted by such devices remain under-characterised.

Purpose

To characterise patients with a first diagnosis of arrhythmia using a smartwatch ECG, and to report subsequent management and short-term outcomes.

Methods

CONNECT is an international, multicentre observational cohort. Participants were enrolled between January 1, 2024, and July 1, 2025, in 19 centres. Eligible participants had an arrhythmia documented for the first time on a smartwatch-recorded ECG. A prior history of arrhythmia was an exclusion criterion. Data were prospectively entered into a secure electronic database.

Results

All in all, 128 patients (mean age 56.0 ± 17.5 years, 62% male) were included. 40 (31.2%) had hypertension and 29 (22.6%) had hypercholesterolaemia. Arrhythmias were detected with Apple (n=60, 49.2%), Withings (n=24, 19.7%) and Samsung (n=15, 12.3%) smartwatches. Physical activity was reported in 69.2% (n=72) of patients, of whom 11% (n=8) exercised between 5 and 10 hours per week and 4% (n=3) exercised more than 10 hours per week. 48 (60%) had a CHA2DS2-VA score of 0 or 1. Palpitations were the leading symptom in 107 patients (83.6%) and 12 (9.4%) were asymptomatic. The two most frequent arrhythmias detected were AF (n=81, 64%) and AVNRT (n=26, 20%). One ventricular tachycardia was documented. Mean left ventricular ejection fraction was 60.9 ± 4.8%.

Regarding the investigations initiated after diagnosis, ambulatory ECG monitoring was performed in 14% (n=18), predominantly for atrial/ventricular ectopy and 29% (n=37) were referred for an electrophysiology study. After diagnosis, oral anticoagulation was initiated in 47% of patients (n=60), including 69% (n=56) of those diagnosed with AF. Antiarrhythmic drugs were prescribed in 60.2% (n=77). Beta-blockers and flecainide were most used (39.8% [n=51] and 21.9% [n=28] respectively).

Median follow-up was 159 days (IQR 59.5-546.2). No deaths occurred and hospitalisation for poorly tolerated arrhythmia or heart failure was uncommon (2.3% [n=3] and 1.6% [n=2] respectively). Catheter ablation was performed in 47.4% (n=54) overall, including 51% (n=37) among those with AF and 56% (n=14) with AVNRT. No ablation was performed for isolated ectopy.

Conclusion

In this multicentre study, patients with smartwatch-detected arrhythmias were relatively young and had comorbidities, with low thromboembolic risk and a predominance of palpitations. The most commonly detected arrhythmia was atrial fibrillation. More than half of patients were prescribed antiarrhythmic drugs and 47% had catheter ablation. These results underline the potential role of connected devices in modern arrhythmia management.