Apple Watch reported false AFIB

Hello everyone!
I happened to have a zio on at the same time I was wearing my Apple Watch. I had a touch up ablation a year ago and was doing great but for some runs of tachycardia here and there- nothing major. I had the zio on during the heatwave in July- happened to be wearing the zio when I wasn’t feeling well- heart beating fast, dizzy- and while it was nowhere near as bad as my episodes pre-ablation- I suspected it was a run of AFIB. And... the Apple Watch, for the first and only time, told me I was in AFIB. Well I got my zio results today and it wasn’t AFIB- it was tachycardia! Needless to say I am thrilled. Not only wasn’t it AFIB- but my heart was unsteady and didn’t go into AFIB which is great. Just wanted to let everyone know that the Apple Watch isn’t foolproof. I don’t have a Kardia but may get one if that is more reliable?
Tracy

I've never owned an Apple Watch so can't comment on it directly, but I've owned a Kardia since 2015. I'm pretty sure the Apple Watch is going to lean conservative and label anything it sees that's questionable as possible afib. From their perspective a false positive isn't a bad mistake but a false negative is a very bad mistake. So that means any rhythm that's irregular is likely to get flagged. Consequently, people who experience lots of PACs or other ectopics are likely to see afib flagged when it isn't actually afib. That's what the Kardia does. I've got numerous recordings that aren't afib but they're irregular so the Kardia labeled them "possible" afib. I don't know what wording the Apple uses, but I bet it's similar.

Both devices are consumer-grade devices, not medical-grade, and they're early designs. I think these devices have a lot of potential but it's still early in their development so they still have weak points.

To add to what Carey wrote, I'd say those devices have no diagnostic purpose. Their main one is to record your HR to show the tracings to your doctor. It's usually what they say in the user's guide. Mine says this on its screen when I turn it on.
Think that cardiologists don't even trust the auto-analyses made by their professional 12-lead ECG machines...

My Kardia is pretty good, not 100% (I've had it for 5 or so years). I also taught myself how to read the ECGs, so I don't depend on the device's analysis. One area where the analysis is likely to fail is detecting a steady rate flutter. In my case, the highly variable r to r times are diagnostic for afib as well as a lack of p wave. If I really want a better look for the p wave, which is hard to see on the left hand - right hand on the contacts (Lead I), I will do a Lead II presentation by holding the device in my right hand and put the left contact by my left hip. This makes the p wave more pronounced.

I've used a Polar r to r recording heart rate monitor for 15 years. The r to r variability is diagnostic for afib for me. I can also discriminate between PAC runs and afib with this. You could manually take the Kardia ecg and manually plot the rr times in milliseconds (or converted to beat rate in BPM) vs time. This presentation is called a tachogram. Tachograms can be generated from a Holter monitor, too.

Examples of tachograms are in these 3 files:
<[www.afibbers.org]
<[www.afibbers.org]\
and a huge number of samples from a former active poster, Mark Robinson, from the UK
<[www.afibbers.org] These are all plotted as heart rate vs time.

George

Reading ECGs is tricky. I was once told by two senior ER doctors that mine showed AF, but when the EP saw it he said it wasn’t, it was runs of ectopics.

Gill.

I want to share something I feel is important before anyone calls up apple for support. DO NOT CALL APPLE TECH AND EVER MENTION YOU HAVE BEEN DIAGNOSED WITH AF. According to their legal department [I was speaking to a supervisor], "the Apple Watch is not designed for patients diagnosed with Afib". That said, they will not give you tech support AND stop answering your questions....and also I speculate they will block on your watch the notification if you are in AF because I have that notification turned on and I never got an alert. With the watch, you can set your low and high HR parameters when you want your watch to alert you. I set it to alert me under 50 and over 90. Also you can setup to alert you when in AF. Both the HR and AF will alert you I believe after 10 or 30 minutes. I forgot.

Because I called them, I no longer get alerts when my HR is over 90 and never no alerts for AF. However I can still take an ECG when in AF and it will say AF....UNLESS your heart rate is over 120 and then you will their their legal friendly alert that your heart rate is over 120 and they cannot detect AF. My HR was 185 according to Apple Watch HR app so I knew it was high....plus I own three ecg monitors so I know the watch is spot on accurate for HR. I took an ECG and got the alert they cannot diagnose if I am in AF or not because my HR is over 120.

quite frustrating. I ended up telling the supervisor [true] that I won't ask him questions for the AF function of the watch because once the new Apple Watch does out I will gift my brand new watch to my daughter. Once I said that, he answered my questions I am suppose to relay to my daughter who thank God never has been diagnosed with AF. However for the time being, my Apple Watch is disabled for alerting me when I am in AF.

I know 100% when in AF...even if my AF is 67 HR. I know ever PAC I get so I don't need the watch to tell me unless I am asleep I suppose. So the purpose of buying the watch was the export feature so I can save a PDF file to show my ER doctors.

I love my watch and it is good to have if you keep your mouth shut and don't call up apple support. I spoke to first tier, second tier, supervisor of the "medical team" who didn't have the answers for "my daughter". I will share some info apple support didn't know -, however it is written in the Apple support webpage. If you are to be cardio converted, take off the watch! Same goes for MRIs and ablations.