Hands-On With the ECG Feature for Apple Watch Series 4 - MacRumorsOpen MenuShow RoundupsShow Forums menuVisit ForumsOpen Sidebar
Skip to Content

Hands-On With the ECG Feature for Apple Watch Series 4

Apple today released the watchOS 5.1.2 update to the public, and the update implements a much-anticipated ECG feature for all Apple Watch Series 4 users in the United States.

Following the launch of the new update, we installed the software and went hands-on with the ECG function to see just how it works.


An ECG, or electrocardiogram, is designed to measure the electrical activity of the heart to detect abnormal rhythms and diagnose serious heart conditions.

The Apple Watch Series 4 allows users to take a single-lead electrocardiogram to keep an eye on heart health. This isn't as informative or as sensitive as the multi-lead ECGs you might get in a doctor's office or hospital, which use several points of contact, but it provides valuable information for those who might not even be aware of a heart condition.

The ECG feature in the Apple Watch uses electrodes built into the sapphire crystal of the Apple Watch (where the heart rate sensor is located) and the Digital Crown that work together to detect the electrical impulses from your heartbeat and route the data to the S4 processor in the device, where it is converted into a signal for Apple's algorithms.

ecg1
You can take an ECG using the built-in ECG app on the Apple Watch, which walks you through the steps. You'll need to place a finger on the Digital Crown of the Apple Watch and wait for approximately 30 seconds while the measurement is taken.

ecg2
You'll see a countdown on your wrist, which is designed to let you know just how long your finger needs to stay in place before you can move it.

ecg 3
Following the conclusion of the ECG, Apple will provide a heart rhythm classification that can be shared with your doctor. If your heart is beating in a normal rhythm, Apple will let you know that a standard sinus rhythm has been detected. If your heart is not beating normally, however, the app will let you know that atrial fibrillation has been detected.

If atrial fibrillation is detected, Apple will suggest that you get in touch with your doctor for further testing.

All ECG results captured with the Apple Watch Series 4 are stored in the Health app in a format that's easy to export and share with your doctor.

ecg 4
Apple has received de novo FDA clearance for the ECG feature in the Apple Watch Series 4, but FDA clearance is not the same as full FDA approval. The FDA does not recommend that the ECG feature be used by those under 22 or those who have already been diagnosed with atrial fibrillation.

The Apple Watch Series 4's ECG function is not designed to replace traditional methods of diagnosis or treatment, and Apple intends for it to be used for informational purposes.

At the current time, Apple Watch Series 4 owners in the United States are the only Apple Watch customers who can take an ECG because the feature needs regulatory approval to be made available in other countries. Apple is working to expand the feature to additional countries.

While the ability to take an ECG is limited to Apple Watch Series 4 users, Apple is implementing a secondary feature designed to send Apple Watch Series 1, 2, 3, and 4 users a notification if an irregular heartbeat is detected via the normal heart rate sensor in the device.

What do you think of the ECG option in the Apple Watch? Let us know in the comments.

Related Roundup: Apple Watch 11
Buyer's Guide: Apple Watch (Neutral)

Popular Stories

earth day 2025 apple watch

Apple Watch Earth Day and International Dance Day Activity Challenges Launching Later This Month

Tuesday April 14, 2026 12:00 pm PDT by
Apple has two new Apple Watch activity challenges coming up, celebrating Earth Day and International Dance Day. The Earth Day activity challenge will launch on Wednesday, April 22, while the Dance Day challenge will take place a week later on Wednesday, April 29. To complete the Earth Day challenge, Apple Watch owners will need to complete a workout that lasts for 30 minutes or longer. This ...
apple watch series 11 spring

Apple Stores Will Soon Be Able to Restore Apple Watch Software In-House

Wednesday April 15, 2026 5:36 pm PDT by
Apple retail locations and Apple Authorized Service Providers will soon be able to restore Apple Watch software in-store without needing to send an Apple Watch to a service center, according to a retail source that spoke to MacRumors. Right now, Apple Watches that can't be restored using an iPhone need to be mailed to an Apple Repair Center for service. There is no in-store repair option, so ...
youtube iphone apple watch health ad 2026

New Apple Ad Sells the iPhone and Apple Watch Health Pairing

Thursday April 23, 2026 11:18 am PDT by
Apple has published a new ad to appeal to customers in the market for an iPhone and Apple Watch pairing, highlighting the insights it can offer for your health. Titled simply "Health with iPhone + Apple Watch," the half-minute ad focuses on a woman waiting in line at a cafe who begins receiving unsolicited health and fitness advice from other people in the queue, as well as local residents,...

Top Rated Comments

ericgtr12 Avatar
97 months ago
I predict a 200% rise in calls to the doctor by tomorrow.
Score: 31 Votes (Like | Disagree)
97 months ago
Why is it America only, exactly? I mean, it's clear some in America have different hearts, but how different is this?
The backhanded comment was absolutely unnecessary.

Edit: I made this comment in the morning. Not actually offended. But leave us Americans alone.
Score: 26 Votes (Like | Disagree)
97 months ago
I can tell you right now... this is going to create a lot of unnecessary anxiety for countless users who see an occasional heart jump on the display. Admittedly, it might help a few people too.
This is gong to be one of those devices that people either obsess on, (100x worse than your iPhone battery capacity meter) or learn to ignore and not use after a few panicked visits to the Dr, reveal nothing can be done about occasional irregular heartbeats.

It's going to be helpful and harmful. The few it helps will come at the expense of the many who develop anxiety disorders staring at it incessantly.
Score: 11 Votes (Like | Disagree)
97 months ago
If that 98bpm is accurate, Dan might need to talk to his doctor about exercise.
Score: 10 Votes (Like | Disagree)
iamgalt Avatar
97 months ago
Why is it America only, exactly? I mean, it's clear some in America have different hearts, but how different is this?
Read the full article. It clearly states that Apple has to get regulatory approval from other counties before it can be made available. Just like they had to get FDA Clearance here in the US.
Score: 10 Votes (Like | Disagree)
97 months ago
It seems a bit absurd that the FDA states this should not be used by those who already have been diagnosed with a-fib. Wouldn't such people want to know if their a-fib is being well controlled by whatever anti-a-fib-whatever their doctor has them on?
Score: 9 Votes (Like | Disagree)
Related Apple News: Education | News | Mac | Iphone | Motoring