Apple Watch ECG won't work when heart rate is high

Question

Apple Watch ECG won't work when heart rate is high

My Apple watch won't capture an ECG when my heart rate is over about 135 bpm. Could this be by design?

Sometimes after a strenuous hill climb while hiking or cycling, when my heart rate was high, I've tried to use the Apple Watch ECG, but for several minutes it can't get any data that looks remotely like my pulse, which feels strong and regular. Only after my heart has slowed down does the Apple watch start to see a rhythm, and it says it's normal sinus rhythm. To get an ECG while my heart rate was still high, I've tried sitting very still, resting my arms on my lap or a wooden fencepost, ensuring the only contact from my opposite arm is my finger touching the crown, leaving my skin sweaty, wiping the sweat away, and even placing the watch on my knee instead of my wrist, but nothing works. I haven't had any feeling of muscle spasms that might account for the chaotic data trace.

Could it be that the Apple Watch ECG software is designed to detect frequencies over about 135 cycles per minute overlaid on a frequency below about 135 bpm, and therefore it can't work when the heart rate itself is higher than about 135?

Posted on Dec 4, 2021 1:03 PM

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Answer 1

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lobsterghost1

Level 10

140,298 points

Dec 4, 2021 1:13 PM in response to Rick_3hiru734

According to Apple see the following:

Low or high heart rate

A heart rate under 50 BPM or over 120 BPM in ECG version 1 affects the ECG app’s ability to check for AFib. In ECG version 2, a heart rate under 50 BPM or over 150 BPM can affect the ECG's app ability to check for AFib.

A heart rate can be low because of certain medications or if electrical signals are not properly conducted through the heart. Training to be an elite athlete can also lead to a low heart rate. Learn more about low heart rates from the American Heart Association.
A high heart rate could be due to exercise, stress, nervousness, alcohol, dehydration, infection, AFib, or other arrhythmia. Learn more about high heart rates from the American Heart Association.

ECG 2 was released with WatchOS 7.2. What WatchOS version do you have running on your Apple Watch?

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Answer 2

Dec 4, 2021 7:29 PM in response to lobsterghost1

I run the most up to date version; it would have been at least WatchOS 7.5, considering the watch was brand new in August. I've checked my data to see what my heart rate was one minute after the ECG result changed from "poor recording" to "high heart rate".

On Sept 1st it was 140 bpm
On Sept 7th it was 133 bpm
On Oct 13th it was 137 bpm

This brings to mind a related bug I need to report: when my heart rate is high and I try unsuccessfully to capture an ECG, inaccurate heart rate data points get saved, for example about 60 bpm when the real rate was over 140 and had been accurately measured up until I attempted the unsuccessful ECG. You can see when I was trying to get ECGs by the garbage heart rate data.

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Answer 3

Dec 4, 2021 7:52 PM in response to lobsterghost1

Thanks for pointing that out. I take it from your posts that the ECG should work at up to 150 bpm, so I have two bugs to report the Apple: the inability to get an ECG above about 135, and the inaccurate heart rate data pints that get saved when I try.

To the community: Is it just me and/or my device? Have you found ECG works at above 135 bpm?

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Answer 4

Dec 4, 2021 7:57 PM in response to Rick_3hiru734

I think it's supposed, but I've never tested it with a high heart rate. Remember, ECG on Apple Watch is not as sophisticated as an ECG you'd get in a doctor's office. So I take any reading as approximate and only something to give me an idea I might need to see my doctor if the reading was not good.

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Answer 5

Dec 4, 2021 8:30 PM in response to lobsterghost1

Yes I'd need a treadmill test with more leads to get authoritative results. Still the user experience design is poor - if ECG isn't designed to work with heart rate above a certain threshold, then when heart rate is above that, the app should notify the user about why it isn't working. [stepping down from my soapbox]

Thanks, lobsterghost1, for the information!

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Answer 6

Dec 4, 2021 7:39 PM in response to Rick_3hiru734

Feel free to report anything you'd like, but not here. This is a user to user only forum. No one here works for Apple.

Use this link --> Feedback - Apple Watch - Apple

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Apple Watch ECG won't work when heart rate is high

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