Published in the New England Journal of Medicine: November 2019 https://www.nejm.org/doi/full/10.1056/NEJMoa1901183

Study was sponsored by Apple

Population: Consisted of 419,297 participants aged 22 years and older from 50 states and District of Columbia who possessed a compatible Apple iPhone and Apple Watch

Intervention: prospective, single group, open-label, siteless, pragmatic study which occurred over 8 months. If an irregular pulse was detected, participants were prompted to initiate a telemedicine visit directly from the app. For urgent symptoms they were directed towards ER. For non-urgent symptoms, an ECG patch (ePatch) was mailed to be used for 7 days.

Comparison: No comparison group

Outcome: Of the 419,297 participants enrolled only 0.52% received an irregular pulse notification. Among those with initial notification who returned an ECG patch, 84% of their notifications were confirmed to be atrial fibrillation and overall yield of atrial fibrillation on ECG patch was 34%.  

Conclusion: The Apple Watch does not change clinical practice. Sensitivity and specificity were both low.  It maybe suitable in situations where people are having palpitations, office ECG and lab work are normal, and ambulatory ECG monitoring such a Holter or event monitor is not available. However, even if the watch does notify the user about an irregular heartbeat, further monitoring using traditional practices as mentioned above will still be needed.

Further upgrades to the Apple Watch may improve its overall utility which will require studies to evaluate its application to clinical practice