Bisher AKIL, MD

Saved by the Watch?

In Heart on November 14, 2019 at 5:29 pm

The Apple Watch has an optical sensor that can detect heart rates, thus introducing the possibility of detecting atrial fibrillation (AF) [Atrial fibrillation (also called AFib or AF) is a quivering or irregular heartbeat (arrhythmia) that can lead to blood clots, stroke, heart failure and other heart-related complications. At least 2.7 million Americans are living with AFib] . The industry-sponsored, prospective [forward] , open-label, siteless, pragmatic Apple Heart Study tested an algorithm to identify AF (NCT03335800). The 419,297 adult U.S. participants enrolled via an app, owned Apple Watches and iPhones, and had no prior AF.

During the study, 2161 people were notified of an irregular pulse, of whom 79% were excluded for various reasons, including 1216 who failed to attend a telemedicine visit. The researchers urgently contacted 20 people: 18 with AF and a rate >200 beats/minute, 1 with a pause >6 seconds, and 1 with non-sustained ventricular tachycardia >6 seconds.

For confirmation, electrocardiographic patches were mailed to 658 participants with nonurgent symptoms. Participants began wearing the patches about 13 days after the notification, for about 6 days. Of 450 people who returned the patches, AF was confirmed in 153 (34%); 20% had continuous AF. The yield was higher in older than younger people. Of 293,015 participants who never received a notification and who returned an end-of-study survey, 3070 reported new AF diagnoses.

As appeared in NEJM – Journal Watch – Edited.

Citations: Perez MV et al. Large-scale assessment of a smartwatch to identify atrial fibrillation. N Engl J Med 2019 Nov 14; 381:1909. (

Campion EW and Jarcho JA. Watched by Apple. N Engl J Med 2019 Nov 14; 381:1964. (


Comments: this is a large study and first of its kind; this maybe what we will see with future studies using wearable health monsters; despite its limitations (no follow up information is a big one), this remains a beginning of a potentially useful mix. Not there yet, though – BA

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