AF and Fitbit pulse monitor: Hi everyone. I... - AF Association

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AF and Fitbit pulse monitor


Hi everyone. I have only had two confirmed occurrences of A. Fib, in May and July last year. I own a Kardia device, but rarely use it. If I feel unwell, I then use it but so far it has only shown normal heart activity since last July when I got good readings of the AF.

I received a Fitbit Charge2 as a Christmas present, and wear it constantly. It has helped me be aware of my activity levels and sleep patterns, but I'm wondering what it would show if I was in A.Fib.? I know that the pulse monitor is two green LEDs and a tiny camera that pick up the rhythm of the 'blushes' when the capillaries expand under the influence of the pulse, but I wonder what effect I might see if I was in AF and there was no rhythm for it to average, and the rate was outside the expected normal. I suspect that it would simply stop showing heart rate, but might it just show the last reading it had, and wait to see a new rhythm?

If anyone has a similar device, and can confirm what it does when AF strikes, that would be very helpful! Thanks.

21 Replies

My wife has a fitbit and based on my observations I wouldn't rely on its readings to measure afib. But I have had similar conversations on this forum and other disagree.

On a related note - I have a polar H7, which is a high quality band. Every time I picked up an irregular heart rate through it I have been in afib. HOWEVER - my colleague used it once and I swore by what i saw that he was in afib and instructed him to go for a medical. His ECG showed he was in rhythm. Maybe it was a lone afib, but it looked just my heart rate does when i am in afib.

momist in reply to Jonathan_C

Thanks Jonathan_C. I'm not really interested in 'measuring' AF with my Fitbit, just using it to alert me to something being wrong, and then referring to the Kardia which is superb for this. My problem is that I don't know for certain that the Fitbit would give me the heads-up.

Jonathan_C in reply to momist

My problem is that I don't know for certain that the Fitbit would give me the heads-up. I would agree with that.

I have PAF and also a Fitbit Charge 2. When I know I've had a short AF episode, I check the Fitbit but it doesn't give me any information I can use. I may be looking in the wrong place. However, my Polar Heart rate monitor, which I bought for the gym, does.

momist in reply to Pam296

Thanks Pam. Seems I might be expecting too much from it then.

Pam296 in reply to momist

There are probably lots of things that it does that I either don't use or don't know it does!

I know I'm in AF from fitbit when it can only give basic sleep details rather than show the sleep stages. Also the amount of exercise time shown, already this morning I've spent over 7 hours in fat burning, cardio and peak exercise zones but I've done nothing. I'm in persistent af tho, not sure what you'll get for short bursts of it.

momist in reply to sharonrc

Thanks Sharon. That's interesting, as I've had a small number of nights where the sleep analysis has reverted to basic mode, and I didn't know why. Maybe I'm having AF at night that I'm not aware of, and I may well have been having it prior to my first recorded event in May when I went into AF during a stressful afternoon/evening of hard work. I'll ask my EP if there is any way I could monitor for that.

I have a Fitbit blaze and track my resting heart rate versus AF episodes. You can't beat Kardia for when you are in AF but the sleep tracking and resting heart rate tracking on the Blaze helps me predict if I maybe having an AF day. What it doesn't do is show you is the actual AF as Kardia does, more an increased heart rate ..

AndyDuk in reply to AndyDuk

For me prior to an AF attack my resting heart rate increases ..

I have a Fitbit Charge 2 and when I was in AFIB for 16 hours last week, I could feel it and my Kardia confirmed it. My heart rate was 150 on the Kardia but the heart rate on Charge 2 was only 60 - 70. I was disappointed in the Fitbit. It did not detect my actual HR. When I exercise my Fitbit show elevated HR so I think it’s working.

momist in reply to Hcoe

Given how the Fitbit detects the pulse, I'm not at all surprised that it doesn't give your actual heart rate, but it is disappointing that it shows some low number equivalent to a normal sinus rhythm heartbeat, despite the lack of regularity. So, I should check with the Kardia more often than I do, and not expect the Fitbit to give me any clue.

i have a Fitbit and a Kardia and am PAF.

When in AF my Fitbit has recoded the increased heart rate accurately anything from 90-160 I also have a Reveal implant which records any AF episodes and that information is sent direct to my Cardiologist. but for my immediate records I rely on the Kardia.

Kardia is great

Hcoe in reply to foxglove1

Which Fitbit do you have? How tight do you wear the Fitbit on your wrist?

foxglove1 in reply to Hcoe

I have a Charge HR 101.

Have had the same one for a few years now and have tested its accuracy of Hr in different ways - always ok.

Hcoe in reply to foxglove1

I upgraded from Charge HR to Charge 2. I would think Charge 2 would do a better job tracking the heart beat. I have been reading that there is a difference between heart rate and pulse. I have always assumed when a heart beats you can feel this in your wrist.

Indeed, Kardia is great, but you have to remember to use it and since it's now eight months since my last AF event, I was looking for something to say "use the Kardia" in case I don't notice AF has started up again. My main problem is that at random intervals the Fitbit shows 'basic Sleep Details' because the heart rate monitor has failed, and I don't know why. Since I only see the sleep record the next day, or another day after syncing the device, I can't be sure if perhaps I went into AF while asleep.The only reason I knew I had gone into AF last year was a strange feeling coming over me, and a weariness. With now being on Bisopralol, I feel a bit weary all the time anyway, and might not think to investigate using the Kardia. I was hoping someone could say "yes, the Fitbit stops seeing your pulse" or "yes, the Fitbit shows different numbers every few seconds" or some such indicator that AF has started. No such luck.

At one point today, I felt a bit strange, and my heart rate was over 70 while not doing anything in particular, which seemed a tad higher than I expected, so I used the Kardia and got a Normal reading. Maybe I was just a bit hungry, and stressed. My son's wedding is on Sunday, and we are very, very busy.

Thanks to everyone who has tried to answer this, but there seems to be no conclusive evidence that the Fitbit can be useful in this way.

I have a Fitbit Blaze and assume I have had an episode when I only get the basic sleep details. I find it useful when exercising to see how my heart rate is doing and the only time I had a really strong episode ending up in resus my Fitbit let me know exactly what my heart was up to.


I have had a Fitbit Charge 2 for a couple of years. I’m in permanent AF but rate controlled and rarely notice my heart rhythm at all.

The machine seems to register a pulse about 99% of the time I would say.

Your point about comparing readings with other devices is interesting. Last week, I was asked to take half hourly BP readings, which showed my HR as well. I also have one of those finger devices that show pulse and oxygen levels. Broadly speaking, the finger device and Fitbit were showing a similar pulse rate but the BP machine was reading higher.

I don’t wear the Fitbit when I go to bed any more. Using the BP machine was counter-productive. I have resolved to go largely by the unscientific method of “how do I feel?” Mainly I use the Fitbit to check whether my HR is higher than usual over a sustained period.

Hylda in reply to Mrspat

My EP said recently he wished people would stop looking at their wrists and start thinking how they felt


Well today was my son's wedding day, and of course once the dancing started I went into AF. An hour later and I've found my Fitbit and while the Kardia reads 168 the Fitbit says 97. So I suppose that answers my question. Yes I shouldn't have a resting HR so high as that, but it's not showing a true rate.

For those of you asking, I have a Charge2 model.

Thank you to all who have responded. I hope this thread helps others who have the same question.

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