Heart rate difference.

[sandw40]

My question is this. Why does the heart rate display on the watch differ at times when doing an ECG?  I have seen my display on the watch show 67 and doing an ECG it will show 127.  I have set alerts to inform me of anything over 110 at rest and never receive anything. Am I missing something?

[jk2310]

Yes, seems like the fitbit sense has been quite inaccurate for the heart rate for me too. Been a Fitbit user since 2015 and this has been a major let down for me.

[sandw40]

Thanks for the info. Really troublesome for me as I bought it to monitor my heart rate because of the Afib that I have.  Now have nothing but questions and no answers!

[SunsetRunner]

Hi @sandw40 ,

I have had an occasional Afib. So far, I got only 1 while using Sense. During that Afib episode, my heart rate was always above 120 and continuously varying, as is typical of Afibs. I took a couple of ECGs which showed good graphs and the correct average heart rate. As it was above 120, ECG's Afib auto-detection always reported "Inconclusive", although I could confirm with the phone app Fibricheck that it was an Afib indeed. Sense's heart rate values were very unstable and with wild variations. At a point it showed 65 bpm when I knew it was above 120, and a few seconds later Sense showed 85 aprox, while the heart rate was near 160.

So, my advice is: if you are having an Afib, don't trust Sense's heart rate values. But you can trust the ECG's, which are not instant values, but a 30 seconds average. That was my experience. Hope it helps.

Concerning Sense's high/low heart rate alarms, they only go off if you are not moving for at least 10 minutes, according to Fitbit Help.

[sandw40]

This was exactly my case. I was sitting reading a book for at least a half hour when the afib episode started so the Fitbit should have fired off an alarm.  Beginning to have some serious regrets about buying this based on advertising claims.

Thanks for the input.

[SunsetRunner]

Hi @sandw40

Just to make it clear, because this can be important.

As far as I know, the only way to detect an Afib with Sense is to start the ECG app, follow the instructions and take an ECG for 30 sec. until it's finished and then the app gives you its evaluation. By itself, Sense has no Afib auto-detection running on the background, so don't expect any Afib alert, besides the ECG app diagnostic. Besides, ECG app doesn't even try to detect any Afib if the heart rate is above 120 or below 50 bpm, giving "Inconclusive" as a result and explaining why. I still don't know for sure how this ECG app performs when an Afib happens within its heart rate limits of 50-120 bpm, never happened to me.

If you have or suspect you may have Afibs, I recommend you take an ECG and then send its PDF report to your doctor (their quality is good and a doctor diagnostic will be more reliable than the app's). You can try also the Fibricheck app, available for smartphones and some other Fitbit devices, but not Sense. With Fibricheck, which uses optical readings and so doesn't provide any ECG, you also need to start it first and then take a measurement for 60 seconds. Like Sense's ECG, Fibricheck was also tested and approved by national health authorities in the US (FDA), European Union and other countries.

My personal opinion is that Fibricheck is better on detecting an Afib at the moment it is happening, helping you to take quick decisions on possible SOS medicines you may have to take on these occasions or going to the hospital, if that is necessary. Besides, it never gave me any false alarm, after using it for more than a year. ECG, on the other hand, is better to show a doctor, because the ECG graph provides more complete medical information than Fibricheck's report.

What I do when I suspect I may have an Afib going on, is:

• Take 1 or 2 measurements with Fibricheck phone app, to be sure it is an Afib and, with that info, take quick decisions on what I have to do.
• Only then I take 1 or 2 measurements with Sense's ECG app, whose PDF report I send to my cardiologist. But she can take several hours or even days to see it and reply, as is usual with doctors that are not by our side at the moment.

You can find more detailed information on Sense's ECG on its Fitbit Help pages, like here .

[SunsetRunner · Accepted solution]

@sandw40 , there is another possible explanation without having any Afib. Though it looks a bit less probable, it seems possible to me.

Sense's Heart Rate readings are known for having a few seconds time lag between the actual HR and the HR value shown by Sense. It could happen that before taking the ECG the HR shown by Sense was 67, which could be the real value a few seconds ago, then you took the ECG and got nervous (it's normal, it happens very often) and you get a 30 seconds average HR of 127. As it is above 120, the ECG app will say the result is inconclusive, anyway.

Does it make sense to you? Anyway, in this case, after the ECG Sense should show a HR value closer to 127.

[sandw40]

Follow the same procedures you mention in 1st 2 paragraphs. Realize there is no auto detect feature but I have the silent version of afib so I occasionally check heart rate and ECG thru out the day.  Also thought I could rely on the heart rate detection alarm settings but that doesn't seem to be very functional either.  Still have my "other" monitor which I think is going to be my primary go to from now on.

thanks. 

[SunsetRunner]

I'm glad I could help, @sandw40 . I know how it feels having these heart issues.

In the beginning I also thought Sense would be more helpful on that. It still is, though, by sending my cardiologist the ECGs. But that's useful only for later, not that moment when it is happening.