A popular fitness tracker company has received approval from the Food and Drug Administration for a new software algorithm to detect atrial fibrillation (AFib), Fitbit announced on April 11.
The algorithm will be the basis of an upcoming Fitbit feature called Irregular Heart Rhythm Notifications, the company said in a press release.
The approval was based on data from the Fitbit Heart Study, which was conducted entirely virtually in more than 455,000 U.S. adults. Participants who had an irregular heart rhythm detected by the software algorithm were notified and invited to meet with a telehealth doctor. They then received a 1-week ECG patch monitor to wear along with the smartwatch or fitness tracker.
Results, presented at the annual scientific sessions of the American Heart Association in November 2021, showed that the positive predictive value of the Fitbit algorithm for detecting undiagnosed AFib with a range of wearable devices was 98%. Notably, irregular heart rhythm detection occurred in 1% of participants overall and 4% of those older than 65 years.
The algorithm works by using an optical measurement method called photoplethysmography (PPG), along with heart rate input from the Fitbit’s photodetector device.
It operates only when the user is still or at rest, so overnight use is important for detection, the company noted.
The upcoming Irregular Heart Rhythm Notifications feature will complement the existing ECG app, providing two ways to detect AFib. The ECG app provides a “spot-check approach” in which the users can screen themselves, and the PPG-based feature will allow for long-term heart rhythm assessment, the statement explained.
“Undiagnosed atrial fibrillation can lead to strokes, and early detection of atrial fibrillation may allow doctors to prescribe medications that are effective at preventing strokes,” said Steven A. Lubitz, MD, MPH, a cardiologist at Harvard University and Massachusetts General Hospital, both in Boston, at the AHA meeting.