Apple Watch Afib data discrepancy?

Rounding errors? It's still well within the 'standard error of measurement' for the device, meaning you apparently have no registered events that you can call up if you poll your record on the watch.

You mentioned that you configured the watch to only collect time in AFib and not to alert when it starts, is that correct? If so how could you an idea of the time in AFib?

As I mentioned in a different post I don't think these devices are literally constantly monitoring for events but looking back at a previous period which for my Fitbit seems to be 10 minute periods.

These devices are still labeled as "consumer grade" and not "medical grade" they are far from perfect no matter the advertising. Example is the stair count feature. I have a set of stairs leading from basement to 1st floor that has 12 steps. I do those stairs literally 8 + trips a day. On most days it records "one" flight on many others "0".

If it can't count stairs I would not put a lot of faith in counting time in AFib.

Please do a holter monitor and that will assist you in determining your A Fib. The cardiologist will interpret the results. The watch is a consumer grade "assistance", however, it is not absolute. My fitbit had stated I had bouts of A Fib. I went to the cardiologist - who I was glad I came - just to check it out. The holter said I did not have A Fib, but very occasional PAC. Very different diagnosis - as the occasional PAC was nothing for me to worry about.

Thanks for the replies. The Apple Watch reports 2 different Afib history metrics: Afib day-to-day over the last six weeks (Mon - Sun), and How my daily Afib changed over the last six weeks (24 hour time period). Given that both metrics use the same data collection technology, it's a mystery to me that the device indicates that I have a 3% Afib burden on Sat & Sun during the past six weeks, yet have a 2% or less burden in any 24 hour period during the same six weeks. I'm guessing it's a bug in the data analysis algorithm.

I'm six months out from PF ablation and I'm currently wearing a Zio patch, which I will be sending in for analysis later this week. Hopefully that will provide more reliable data. I certainly hope so because based on the results, the EP will decide whether I can cut back on my meds.

My watch records the same, 2% or less since my cardiologist set my watch up for me. Figure it means no afib. But agree with other, if it can't even count steps, how can it accurately measure afib?

IWatch can misconstrue PACs as Afib. I was reading 10% Afib, 2 weeks on heart monitor showed none. Be careful relying on IWatch or any other device.

@the so glad to read this as mine said 10% and I was tripping

@glitterchromatic That is why the wearer of the watch might wish to educate his/herself about what the watch's ECG looks like when the heart rhythm is normal, near normal, abnormal, and showing clear signs of AF (atrial fibrillation). If your watch keeps saying you have some AF, then take frequent ECGs and look at their graphic representation. AF shows as an ECG with no p-wave and continuously varying intervals between the r-to-r peaks. Once your brain 'sees' and knows what to look for, there will be no mistake about whether-or-not it's AF. I sent my Samsung Galaxy's readout, downloaded to my PC, to my electrophysiologist because it clearly showed no p-wave and the peak-to-peak intervals were all over the place in length. He immediately replied that, yup, you have recurrent AF and he later scheduled me for a second ablation, no questions asked (Galaxy watch redout was good enough).

Interesting discussion. I wear an Apple Watch and a Fitbit. Both devices track my AFib, but my research indicates the Apple Watch has a better algorithm. Last night and this morning (28 Feb-1 Mar) my Fitbit recorded some significant AFib events, but for the first time in nearly 3 years, my Apple Watch recorded no events. Apple Watch was fully charged at bedtime. I have AFib History enabled on the Apple Watch and have been getting regular updates.

@stryker66 I hope I don't come across as callous or dismissive....not my intent. We don't know each other, I don't know your history, and I'm no health expert...not by any means. Just taking what you have 'said' at face value, and mixing it with what I have learned (mostly for and about myself), humans tend to be biased toward information that appears to support or to confirm what they WISH TO believe....what they HOPE is true. This is widely known as 'confirmation bias'. I think, without knowing much about the two devices, that there is some danger here for you in assuming the 'better news' is correct. It may very well be that you are correct, and that the Apple watch is better, but remember that the FDA or whomever has approved BOTH devices for sale and with active apps that measure health passably accurately, enough that they are meant to inform. But different devices sit on the wrist differently due to differences in engineering and in form factor. Maybe one of their bands feels better for you when it's a bit tighter, and when it therefore gets better information, than the other. But which is it....which one....and how can you tell?

Not trying to rain on your parade. I would hope, for your sake, that the Apple IS the better of the two. But you can't be sure without some other measure that confirms it. Maybe, if you're up to the experiment and the relatively modest outlay of cash, a Kardia mobile or some other worn device would allow you to do that....confirm.