Apple Watch Series 4 – How to take an ECG

I previously reviewed the Apple Watch Series 4 when it first launched and I was looking forward to trying the ECG feature. The app for highlighting irregular heartbeat is now live, and it allows you to take an electrocardiogram (ECG or EKG) right from your wrist and I wanted to share my initial thoughts on it.

It monitors Atrial fibrillation (also called AFib or AF) simply known as a irregular heartbeat that could lead to heart-related health complications. If left untreated AFib is one of the primary conditions that could result in a stroke, which is the second most common cause of death around the world. The benefit of this app is that wearers can be warned of abnormal heart rhythms associated with atrial fibrillation, which can help provide critical data to physicians.

The feature is now available in 19 European countries, including France, Germany, Italy, Spain and the United Kingdom. The ECG app and irregular rhythm notification are now CE marked and cleared in the European Economic Area.

How does it work?

Firstly update the software on your iPhone and Apple Watch Series 4.

Essentially it uses the electrodes in two areas of the Apple Watch Series 4 which work together, in the back crystal and the Digital Crown.

The user opens the app and holds their finger on the Digital Crown. As the user touches the Digital Crown, the circuit is completed and electrical signals across their heart are measured for 30 seconds. Once it gives you a result you can scroll down and add any relevant symptoms that your experiencing.

The heart rhythm results are classified under the three categories:

  1. AFib: This result means that the heart is beating in a irregular pattern and is the most common form of serious arrhythmia. This occurs when the upper chambers of the heart beat out of sync with the lower chambers and this creates the irregular pattern.
  2. Sinus rhythm: This result means the heart is beating in a uniform pattern. This happens when the upper and lower chambers of the heart are beating in sync.
  3. Inconclusive: this result will occur if the ECG app detects a 50 BPM or over 120 BPM. My resting heart rate is in the low 40s so often I would have an inconclusive reading, but it is well known that being aerobically fit can result in a low heart rate. Whereas a high heart rate could be due to exercise, stress, alcohol, infection or any other arrhythmia. So for me to get my result (as shown above) I’d walk at a normal pace first to pick up my heart rate slightly, before sitting to taking the test. Otherwise I get an inconclusive result if I’m just sitting normally (as shown below).

All the recordings are then noted securely in the Health app on the iPhone. And you can then share the data with your physician.

Additionally if you go into the Watch app on your iPhone, you can turn on the irregular rhythm notification which will alert the user if a irregular rhythm is detected on five rhythm checks over a minimum of 65 minutes.

To sum up:

When I ran the Half Marathon Des Sables in 2018, I needed a medical sign off which included an ECG. Using this technology could of aided my physician in their assessment. However you don’t need to be an ultra runner to have use for this feature. Having information readily available can only help you be aware of the health features that are monitored.

Whilst these are early days, beyond being a fitness and smart watch, this looks like the start of Apple’s work in the health industry and I look forward to seeing how this technology progresses, as health monitoring potentially can help the user make better informed decisions.


  1. Brilliantly informative and instantly useful Marcus, thanks for another great blog post.

    Liked by 1 person

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