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

TLDR

Wearable devices can passively measure pulse rate via photoplethysmography, and detecting pulse irregularity from these data could identify atrial fibrillation or flutter, enabling large‑scale screening given the rapidly expanding consumer base. The study aims to determine the proportion of Apple Watch users whose irregular pulse notifications correspond to atrial fibrillation on ambulatory ECG patches, while also evaluating notification concordance and subsequent healthcare contact. Participants were enrolled and consented through a smartphone app, with telehealth physician visits conducted via video chat and ambulatory ECG patches mailed for confirmation. Initial results suggest that the smartwatch algorithm can detect pulse irregularity and variability that may indicate previously unknown atrial fibrillation.

Abstract

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.