We read with great interest the meta-analysis by Barrera et al1 evaluating smartwatch accuracy for atrial fibrillation (AF) detection. We commend the authors for this timely synthesis of a rapidly evolving field. Their findings highlight the enthusiasm for digital rhythm monitoring, yet pooled estimates differ markedly from real-world data, where specificity and positive predictive value are lower.2 Methodological factors may explain these discrepancies and should be clarified before applying such metrics in practice.
The analysis combines photoplethysmography (PPG) and single-lead electrocardiogram (ECG) models as equivalent diagnostic tools. This is misleading: PPG detects pulse irregularity, whereas ECG confirms AF through electrical activity. Merging detection and diagnosis inflates the perceived reliability of smartwatch screening.
Heterogeneity mainly reflects differences in device algorithms rather than study design. Each manufacturer applies proprietary thresholds and duration criteria affecting alert frequency and missed AF. Algorithmic updates further limit comparability.3 Moreover, few studies report the performance of the entire sequence (PPG alert → ECG validation), and nonqualifying ECGs—often excluded—may account for up to 25% of tracings in practice.2
Diagnostic accuracy also depends on the prevalence of AF. In postoperative settings, where irregular rhythms are frequent, specificity and positive predictive value decline, generating excessive alerts and false positives.4 Beyond numbers, repeated “possible AF” notifications can cause anxiety and unnecessary consultations, recalling earlier experiences with device-detected subclinical AF.5
In summary, smartwatches have brought AF detection to the wrist, but the challenge lies in translating alerts into clinically meaningful diagnoses. Until then, every AF detection should be confirmed by ECG review.5
To alert is good; to confirm is better.
Footnotes
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
References
- 1.Barrera N., Solorzano M., Jimenez Y., Kushnir Y., Gallegos-Koyner F., Dagostin de Carvalho G. Accuracy of smartwatches in the detection of atrial fibrillation: a systematic review and diagnostic meta-analysis. JACC Adv. 2025;4(11 Pt 1):102133. doi: 10.1016/j.jacadv.2025.102133. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Mannhart D., Lischer M., Knecht S., et al. Clinical validation of 5 direct-to-consumer wearable smart devices to detect atrial fibrillation. JACC Clin Electrophysiol. 2023;9:232–242. doi: 10.1016/j.jacep.2022.09.011. [DOI] [PubMed] [Google Scholar]
- 3.Isenegger C., Mannhart D., Arnet R., et al. Accuracy of smartwatches for atrial fibrillation detection over time: insights from the basel wearable study. JACC Clin Electrophysiol. 2024;10:2735–2737. doi: 10.1016/j.jacep.2024.09.019. [DOI] [PubMed] [Google Scholar]
- 4.Monteiro R., Rabello G.C.M., Moreno C.R., et al. Enhancing cardiac postoperative care: a smartwatch-integrated remote telemonitoring platform for health screening with ECG analysis. Front Cardiovasc Med. 2024;11 doi: 10.3389/fcvm.2024.1443998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Van Gelder I.C., Rienstra M., Bunting K.V., et al. 2024 ESC guidelines for the management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS) Eur Heart J. 2024;45:3314–3414. doi: 10.1093/eurheartj/ehae176. [DOI] [PubMed] [Google Scholar]