Validation of an algorithm for continuous monitoring of atrial fibrillation using a consumer smartwatch

Heart Rhythm. 2021 Sep;18(9):1482-1490. doi: 10.1016/j.hrthm.2021.03.044. Epub 2021 Apr 8.


Background: Consumer devices with broad reach may be useful in screening for atrial fibrillation (AF) in appropriate populations. However, currently no consumer devices are capable of continuous monitoring for AF.

Objective: The purpose of this study was to estimate the sensitivity and specificity of a smartwatch algorithm for continuous detection of AF from sinus rhythm in a free-living setting.

Methods: We studied a commercially available smartwatch with photoplethysmography (W-PPG) and electrocardiogram (W-ECG) capabilities. We validated a novel W-PPG algorithm combined with a W-ECG algorithm in a free-living setting, and compared the results to those of a 28-day continuous ECG patch (P-ECG).

Results: A total of 204 participants completed the free-living study, recording 81,944 hours with both P-ECG and smartwatch measurements. We found sensitivity of 87.8% (95% confidence interval [CI] 83.6%-91.0%) and specificity of 97.4% (95% CI 97.1%-97.7%) for the W-PPG algorithm (every 5-minute classification); sensitivity of 98.9% (95% CI 98.1%-99.4%) and specificity of 99.3% (95% CI 99.1%-99.5%) for the W-ECG algorithm; and sensitivity of 96.9% (95% CI 93.7%-98.5%) and specificity of 99.3% (95% CI 98.4%-99.7%) for W-PPG triggered W-ECG with a single W-ECG required for confirmation of AF. We found a very strong correlation of W-PPG in quantifying AF burden compared to P-ECG (r = 0.98).

Conclusion: Our findings demonstrate that a novel algorithm using a commercially available smartwatch can continuously detect AF with excellent performance and that confirmation with W-ECG further enhances specificity. In addition, our W-PPG algorithm can estimate AF burden. Further research is needed to determine whether this algorithm is useful in screening for AF in select at-risk patients.

Keywords: Atrial fibrillation; Atrial fibrillation burden; Photoplethysmography Remote monitoring; Screening; Smartwatch.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Aged
  • Algorithms*
  • Atrial Fibrillation / diagnosis*
  • Atrial Fibrillation / physiopathology
  • Electrocardiography / methods*
  • Equipment Design
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Monitoring, Physiologic / instrumentation*
  • Photoplethysmography / instrumentation*
  • Retrospective Studies
  • Telemedicine / instrumentation*
  • Wearable Electronic Devices*