Fitbit users will soon have a new piece of health information right at their fingertips (or wrists): The company announced this week that they’ve received clearance from the U.S. Food and Drug Administration (FDA) for the technology that powers their new irregular heart rhythm notifications feature.
The Fitbit atrial fibrillation software is an algorithm based on photoplethysmography, which uses a light source and a photodetector on your skin’s surface to measure changes in your blood circulation and volume. Every time your heart beats, Fitbit says, your blood vessels expand and contract based on these changes in blood volume. The wrist-based sensor on the Fitbit can measure these changes, which determines your heart rhythm. Then the new algorithm analyzes this data for any variations that may signal atrial fibrillation, or a fast irregular heartbeat.
According to the Mayo Clinic, atrial fibrillation (AFib) often occurs without symptoms, though for some people it can lead to palpitations or shortness of breath. The danger with AFib is that it can lead to blood clots, which can raise your risk of stroke. People who have conditions like high blood pressure, thyroid disease, or chronic conditions like diabetes may be at increased risk of developing it.
Fitbit’s devices have measured resting heart rate and workout heart rate for years, but their tracking footprint has grown recently to include irregularities. In 2020, Fitbit announced that it received clearance from the FDA for its electrocardiogram (ECG) app, which premiered on its Fitbit Sense device (which also included additional health-tracking features like skin temperature and oxygen saturation monitoring). This ECG app allowed for on-the-spot readings to detect for AFib.
Now, Fitbit’s new algorithm seeks to take this one step further by passively checking your heart rhythm for irregularities while you’re at rest or asleep. If these background readings detect something potentially abnormal, you’d be notified through Fitbit’s irregular heart rhythm notifications feature. Then, Fitibit says, you can take this information to your health care provider.
According to the company, data for the new software comes from its Fitbit Heart Study, a large-scale study that launched in 2020 and included more than 450,000 participants. In November of 2021, the company presented their research at the American Heart Association’s Scientific Sessions 2021 and announced that their new algorithm accurately detected irregular heart rhythms and undiagnosed atrial fibrillation 98% of time.
According to the Verge, Fitbit’s new background detection of heart irregularities brings its heart monitoring capabilities more in line with that of the Apple Watch, which launched their ECG app and irregular heart rhythm notifications in 2018. Fitbit hasn’t given a specific launch date for their new AFib detection, or which of their fitness tracker models will feature it, though they have said it’ll be available “soon” to U.S. consumers “across a range of heart-rate enabled devices.”