Fitbit users are getting this life-saving free update

Good news for Fitbit users: from today you're getting an important new feature that's much more significant than most software updates. Fitbit has been cleared by the US Food and Drug Administration to notify users when their Fitbit tracker detects signs of Atrial Fibrillation, AFib for short. The notifications, which Fitbit calls Irregular Heart Rhythm Notifications, are rolling out to nine different Fitbits from today.

As 9to5Google reports, the devices are:

• Fitbit Sense
• Fitbit Versa
• Fitbit Versa 2
• Fitbit Versa Lite
• Fitbit Charge 5
• Fitbit Luxe
• Fitbit Charge 4
• Fitbit Charge 3
• Fitbit Inspire 2

How your Fitbit could save your life

Atrial Fibrillation is when your heart beats in an abnormal rhythm, often unusually quickly, and it's often associated with other heart conditions. It's notoriously difficult to diagnose because sometimes people don't have any symptoms, so they don't get their hearts checked. It makes your heart less efficient and it's the most common kind of heart disturbance; it tends to affect men more than women and is more common in older people.

It's important to detect AFib because it increases your risk of having a stroke, and it can be unpleasant in its own right. So having your Fitbit warn you if it spots the signs of AFib can be genuinely life-saving: the condition is treatable, and as with any serious medical issue early diagnosis is helpful. Your Fitbit will take readings when you're still or when you're asleep, and it'll notify you if there's anything you need to talk to the doctor about.

The irregular heart rate feature isn't the same as the ECG (Electrocardiogram) in the Fitbit Sense and Fitbit Charge 5; that requires hardware that only those Fitbits currently have. Instead, It uses an algorithm that, according to Fitbit, is 98% effective at detecting AFib compared to a dedicated ECG machine.

The new feature is rolling out from today but may take a week or two to arrive on everyone's devices.