Fitbit is in the process of rolling out a software update that will add an abormal heart rhythm sensing feature to nine of its trackers, including several that are fairly old, according to 9to5Google.
If you own a Fitbit Charge 3, 4 or 5, a Versa 2/3 or Lite, a Fitbit Sense, Inspire 2 or Luxe, your tracker is on the list.
This follows an FDA approval for a passive atrial fibrillation solution, which is quite different to those used by Apple and Samsung.
Wearables that can detect potential heart rhythm abnormalities like atrial fibrillation typically use an ECG array, where two nodes on the band are used to pass a weak electrical signal through the body.
Fitbit’s new implementation is supported by numerous watches that have no ECG hardware at all, telling us the feature relies on the optical heart rate array. The latest versions of these use green LEDs to judge heart rhythm and red/infrared LEDs to estimate blood oxygen saturation.
Atrial fibrillation typically presents as an irregular, and often fast, heart rate — nothing outside of the purview of a good optical HR scanner.
The Fitbit approach is passive, meaning tests will happen automatically rather than being manually started, as with a wearable’s ECG feature. This should make it more useful for many, given there’s no need to deliberately take a couple of minutes out of your day to do an ECG test and take a look at the results.
It also helps avoid the main issue of using optical hardware for this purpose. Wearables makers typically have to use a lot of error correction algorithms to spit out cogent results. By operating in the background, Fitbit can perform the test when you are still — overnight being the obvious choice.
Fitbit users in the US can expect to see the software update arrive soon, and the feature will be called Irregular Heart Rhythm Notifications.