Apple Watch and The ECG

Wearable technology has been around for a number of years now, enabling anyone to monitor their steps, exercise and send/receive messages straight from their wrist, as well as tell the time.

Most of this wearable tech used to simply just tell you what your heart rate was up to, whether it was too high, or too low, throughout the day. But this technology has advanced in the past year, with the launch of the ECG app on the Apple Watch Series 4.

For those not in the know, an electrocardiogram (ECG), is a test that is used to track your hearts rhythm and electrical activity. If done in a hospital or healthcare setting, chances are it’s a twelve lead ECG with six stickers on your chest with placements surrounding the 4thintercostal space to the left and right of the sternum, the 5thintercostal space on the midclavicular line, one between that and the 4thspace, one on your midaxillary line and one on each arm and leg. For a test that in most cases can take just a few minutes, accuracy of these electrode placements is of importance.

The Apple Watch simply takes all of the above and focuses on one single lead to produce a standard 10 second ECG strip at the same paper speed of 25mm/sec and collaboration of 10mm/mv. The digital crown on the watch contains a titanium electrode that reads the electrical heart impulses in your fingertips, while a silicon carbon nitride layer applied to the back of the watch reads the electrical impulses in your wrist. 

To take an ECG on the Apple Watch, once the app has been opened, you simply hold a finger on the digital crown for thirty seconds. Once complete, you’ll be told the rhythm on your watch, with the full ECG recording sent straight to the Health app on your iOS devices, where you can see the full tracing. Here’s mine: 

My Apple Watch ECG

And apart from the slight baseline way at the beginning where I was getting my arm comfortable, I think the tracing is of reasonable quality. It’s everything you’d expect on an ECG (standard paper speed etc) and the recording is readable, more so than some of the print outs I’ve done or seen in the past. At this point, I’d say I like the quality and way it is presented, but of course am hesitant with how the results could be interpreted.

The ECG app tells you if you’re in Sinus Rhythm (SR) or atrial fibrillation (AF), but it won’t tell you (and can’t tell) if you’ve had a heart attack, or any other rhythms. If you have a rhythm other than SR or AF, it’ll come back as inconclusive. You are advised after recording the ECG to consult your doctor if you are concerned about the findings – and you can email the clinic or your doctor the full tracing right from within the Health app.

This has caused some people in the health profession to be concerned on what patients might think, especially those who feel anxious anyway about their heart conditions. There’s also no guarantee that the tracing will be 100% accurate; despite Apple’s extensive testing in America, there are occasions where it may misdiagnose patients. 

This type of wearable tech and the ability for users to perform these types of tests on themselves are only going to continue to grow and expand as the years go on and as technology advances. This technology won’t override the importance of seeing professionals in clinic to have more robust versions of these tests done just yet – if you are worried about an ECG performed on an Apple watch, I would strongly advise getting another reading from your doctor, using the traditional method detailed above, but I’d say in the next five or ten years, these could become the norm, with patients using these tools at their disposal, before seeing professionals in clinics.

What we need to do as healthcare professionals is work on patient education – educate patients on how this technology works, the pros and cons and remind them that it’s not a replacement for seeing a professional in clinic, who has years of knowledge at his/her disposal compared to the Apple Watch’s year old ECG function, which, whilst being out of beta, is still relatively new.

Stories have emerged of how the ECG app has potentially saved people’s lives. One notable one from the UK, this chap was training for a marathon.

He felt symptoms, was nudged by his wife to do an ECG check on his watch and showed his results to the doctors. The end result ended up with the chap needing open heart surgery, which he attributes to the ECG app. Whilst the app detected a warning for atrial fibrillation, that alone would not have been a cause to go into open heart surgery. It is likely other tests were needed prior to the surgery being decided. So, whilst it worked well as a detector in this case, it’s merely a stepping stone for other tests, done in clinical settings, to determine the overall outcome. 

It’ll be interesting to see how (and if) Apple advance their ECG software in future updates and releases and if other companies of wearable tech such as Fitbit and Samsung follow suit in the future. 

Whether we like it or not as clinicians, this is slowly becoming the norm and like all medical treatments, we’ve got to learn to adapt, educate and inform patients to the best of our ability.

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