Key result
The Apple Watch irregular rhythm notification feature demonstrated 21.4% sensitivity and 100% specificity for detecting atrial fibrillation, while the manual ECG feature achieved 100% sensitivity and 99.1% specificity.
Why the study?
As smartwatches with atrial fibrillation detection gain popularity, assessing their accuracy is necessary to guide clinical decision-making.
Does the Apple Watch accurately detect atrial fibrillation compared to a 24-hour Holter monitor in patients with clinical indications for rhythm monitoring?
Observational (n=140)
No
Does the Apple Watch accurately detect atrial fibrillation compared to a 24-hour Holter monitor in patients with clinical indications for rhythm monitoring?
While the Apple Watch's automatic irregular rhythm notification has low sensitivity for detecting atrial fibrillation, its manual ECG feature is highly accurate and reliable when compared to 24-hour Holter monitoring.
Manual ECG feature may aid monitoring in indicated patients; leaves open validation of automatic notifications before practice change.
BACKGROUND: As smartwatches with atrial fibrillation detection features gain popularity, it is important to assess the accuracy of these devices to guide decision-making. OBJECTIVES: Our study aimed to assess the sensitivity and specificity of the irregular rhythm notification and the electrocardiogram (ECG)–based detection features of a commonly used smart wearable device (Apple Watch) in detecting atrial fibrillation. METHODS: This was a prospective, pragmatic study conducted in Perpetual Succour Hospital–Cebu Heart Institute from August 2023 to January 2024. To assess the irregular rhythm notification feature, participants were asked to wear an Apple Watch alongside a 24-hour Holter monitor to verify notifications. For the ECG-based detection feature, participants had to tap the crown of the Apple Watch for 30 seconds to get a single-lead ECG similar to a lead I ECG tracing. They were instructed to get manual ECGs hourly, or more often while awake. Irregular rhythm notifications and ECG readings were then compared with that of the 24-hour Holter monitor. Sensitivity and specificity were then computed. RESULTS: A total of 140 participants consented to join after full study disclosure. The irregular rhythm notification feature of the Apple Watch exhibited a low sensitivity of 21.4% but achieved a high specificity of 100% in detecting atrial fibrillation. Meanwhile, the ECG-based detection feature, analyzed from 1295 manually taken ECGs with interpretable sinus rhythm or atrial fibrillation, demonstrated a high level of agreement with the Holter monitor, with a sensitivity of 100% and a specificity of 99.1%. CONCLUSION: The low sensitivity of the irregular rhythm notification feature of the Apple Watch in detecting atrial fibrillation cautions against relying on it as a primary screening tool. However, the high concordance of manually taken Apple Watch ECGs positions the device as a robust tool for detecting atrial fibrillation through manual ECG detection.
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Inocian et al. (2024) conducted an observational in Suspected arrhythmias (undergoing 24-hour Holter monitoring) (n=140). Apple Watch (irregular rhythm notification and ECG-based detection) vs. 24-hour Holter monitor was evaluated on Sensitivity and specificity for detecting atrial fibrillation. The Apple Watch irregular rhythm notification feature demonstrated 21.4% sensitivity and 100% specificity for detecting atrial fibrillation, while the manual ECG feature achieved 100% sensitivity and 99.1% specificity.
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