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Am Heart J. 2019 Jan;207:66-75. doi: 10.1016/j.ahj.2018.09.002. Epub 2018 Sep 8.

Rationale and design of a large-scale, app-based study to identify cardiac arrhythmias using a smartwatch: The Apple Heart Study.

Author information

Center for Digital Health, Stanford University Stanford, CA; VA Palo Alto Health Care System, Palo Alto, CA. Electronic address:
Quantitative Sciences Unit, Stanford University, Stanford, CA.
Stanford Center for Clinical Research, Stanford University, Stanford, CA.
Information Resources and Technology, Stanford University, Stanford, CA.
Apple Inc. Cupertino, CA.
Lankenau Heart Institute and Jefferson Medical College, Philadelphia, PA.
University of Colorado School of Medicine, Denver, CO.
Division of Cardiovascular Disease, Cooper Medical School of Rowan University, Camden, NJ.
9, American Foundation for Women's Health, Decatur, TX.
Duke Clinical Research Institute, Duke University, Durham, NC.
Division of Cardiovascular Medicine, Stanford University, Stanford, CA. Electronic address:



Smartwatch and fitness band wearable consumer electronics can passively measure pulse rate from the wrist using photoplethysmography (PPG). Identification of pulse irregularity or variability from these data has the potential to identify atrial fibrillation or atrial flutter (AF, collectively). The rapidly expanding consumer base of these devices allows for detection of undiagnosed AF at scale.


The Apple Heart Study is a prospective, single arm pragmatic study that has enrolled 419,093 participants (NCT03335800). The primary objective is to measure the proportion of participants with an irregular pulse detected by the Apple Watch (Apple Inc, Cupertino, CA) with AF on subsequent ambulatory ECG patch monitoring. The secondary objectives are to: 1) characterize the concordance of pulse irregularity notification episodes from the Apple Watch with simultaneously recorded ambulatory ECGs; 2) estimate the rate of initial contact with a health care provider within 3 months after notification of pulse irregularity. The study is conducted virtually, with screening, consent and data collection performed electronically from within an accompanying smartphone app. Study visits are performed by telehealth study physicians via video chat through the app, and ambulatory ECG patches are mailed to the participants.


The results of this trial will provide initial evidence for the ability of a smartwatch algorithm to identify pulse irregularity and variability which may reflect previously unknown AF. The Apple Heart Study will help provide a foundation for how wearable technology can inform the clinical approach to AF identification and screening.

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