ECG on the Fitbit Sense is Finally Live

I’ve been covering the new Fitbit Sense extensively on my own YouTube channel, and also on Medium’s new consumer tech publication, Debugger. When I first got the watch–which is Fitbit’s most advanced smartwatch to date–I wrote a detailed initial review on Debugger. I’m also working on a longer-term review (also for Debugger) which will cover what it’s like to actually use the watch in daily life, including using it to track stress, sleep, exercise, and more.

One much-touted feature of the Fitbit Sense which I wasn’t able to evaluate when the watch first shipped, though, is its electrocardiogram (or ECG) functions. These were only cleared by the FDA in the United States and CE in Europe about a week before the watch shipped, so it appears that Fitbit didn’t have time to actually roll the feature out when the Sense began to ship on September 25.

The company promised that the feature would be live by October, and they’ve delivered on that promise. As of yesterday, ECG functions are now live on the Fitbit Sense. If you have a Sense already, you can now begin to use the ECG functions, with a few setup steps.

Firstly, what is an ECG, and what is it used for? An ECG tracks the electrical activity of your heart. Fitbit’s PurePulse 2.0 heart rate tracking–which has been present on its watches for years now–only tracks the physical beats of your heart. It doesn’t look at your heart’s electrical activity. Issues with your heart’s electrical activity can be a sign of Atrial Fibrillation, a serious condition that increases the risk of stroke, heart failure, and other complications. Checking for the condition using your watch is a great health-oriented feature for Fitbit’s most health-centric smartwatch.

According to an email I received from Fitbit, “Before you can initiate an ECG reading, you must complete the brief introduction on the Heart Rhythm Assessment. This can be found by going to the Discover tab in the Fitbit app and selecting Assessments & Reports at the bottom. Once the introduction is complete, the ECG app will automatically be installed on your watch after you sync.”

I completed my own assessment, which required answering a few questions about my age (you have to be 22 or older to use the feature), etc. My app didn’t install automatically, so I followed Fitbit’s recommendations to “manually download the app from the Fitbit App Gallery (under the My Apps section) in the Fitbit app.” After the install, an ECG app appeared on my Fitbit Sense.

New ECG app on the Sense

I opened the app, which walked me through the process of taking an ECG reading. To do this, you have to sit still and not speak or move your arm for 30 seconds. The app instructs you to put your thumb and index finger on opposite corner’s of the watch’s bezel. The bezel has integrated electrical sensors which are used for the ECG reading, as well as other readings like Fitbit’s EDA scans.

After 30 seconds, the watch finishes gathering data, and spends a few seconds crunching it. It then returns its analysis, which Fitbit says is

There are three possible outcomes, according to Fitbit’s email:

  • Atrial fibrillation: Your heart rhythm shows signs of atrial fibrillation, an irregular heart rhythm. You should talk to your doctor about this result.
  • Normal sinus rhythm: Your heart rhythm appears normal.
  • Inconclusive: If your heart rate is below 50 bpm or above 120 bpm, the ECG app will be unable to access your heart rhythm. This can happen for many reasons, such as moving too much, not resting your hand on the table when recording, wearing your band too loose, or due to certain medications or having excellent aerobic fitness. 

My own reading came back showing a normal sinus rhythm! At least as of when I took my reading, my heart was working well.

One of the challenges with AFib is that is can be “difficult to detect”, according to Fitbit, so it’s wise to take multiple readings over a period of time–especially if you think you’re experiencing symptoms like heart palpitations. Of course, if you think there’s any chance you’re in imminent cardiac danger, stop futzing with your watch and call 911.

Another helpful feature of the ECG app is the ability to download an ECG report to share with your doctor. This includes the raw output of the ECG reading, which you doctor should be able to interpret better than an algorithm, based on their medical training.

Fitbit’s report also shares some details about the accuracy of their system (in case your doctor isn’t convinced), and the fact that it’s comparable to a 1 lead ECG. Again, because it has been FDA cleared, the device should be accurate enough to provide medically useful data, even if it can’t direct diagnose you with a disease.

With the new ECG feature, Fitbit has taken yet another step towards making the Sense the premier health tracking watch on the market today.

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