The Food and Drug Administration cleared a second Fitbit feature that detects atrial fibrillation, the activity tracker and wearables brand said Monday.
The new algorithm passively monitors wearers' heart rate data in the background to identify signs of AFib, a type of irregular heart rhythm. In 2020, the FDA cleared Fitbit's electrocardiogram app that screens for signs of AFib when requested by a wearer, which the company calls a "spot check."
Fitbit, which is owned by Google, will make the new AFib detection feature available to U.S. customers "soon," according to a company blog post.
AFib detection has been a popular area of focus for activity trackers, which have traditionally targeted the direct-to-consumer wellness market. Apple in 2018 scored FDA clearance for an ECG app in its Apple Watch, becoming the first major consumer wearables company to do so. Since then, competitors like Samsung and Withings have also added the capability.
AFib, a condition the American Heart Association said at least 2.7 million Americans live with, increases risk of heart complications like stroke and heart failure.
But while wearables companies have promoted their devices as tools to increase early AFib detection, some physicians have raised concerns that constant screening among healthy patients could prompt unneeded medical visits. One recent study suggested most patients who use the Apple Watch wouldn't qualify for a medication prescribed to AFib patients, even if the condition was flagged.
Fitbit's team on Monday said integrating AFib detection tools into its consumer wearables can help identify the condition in patients who don't have other symptoms. When the algorithm detects signs suggestive of AFib, it notifies the wearer of the irregular heart rhythm and prompts users to talk with a healthcare provider about further assessments.
"Unfortunately, AFib can be difficult to detect as there are often no symptoms and episodes can come and go," the Fitbit team wrote in the company blog post. The team said it will work with Bristol-Myers Squibb-Pfizer Alliance, which develops education materials about AFib and venous thromboembolism, to create resources for patients and providers.
The new algorithm uses photoplethysmography, a technique that detects changes in a wearer's blood volume, to screen for AFib during periods of inactivity, such as while users are asleep.
Fitbit validated the algorithm through a study it conducted in 2020 with researchers from Massachusetts General Hospital.
The study found that Fitbit's algorithm accurately identified undiagnosed AFib 98% of the time, according to findings presented at an American Heart Association conference last year. Just 1% of the more than 455,000 participants who enrolled in the study had an irregular heart rhythm detected.