ECG app and irregular heart rhythm notification available today on Apple Watch

Starting today, the ECG app on Apple Watch Series 4 marks the first direct-to-consumer product that enables customers to take an electrocardiogram right from their wrist, capturing heart rhythm in a moment when they experience symptoms like a rapid or skipped heart beat and helping to provide critical data to physicians. The irregular rhythm notification feature on Apple Watch can now also occasionally check heart rhythms in the background and send a notification if an irregular heart rhythm that appears to be atrial fibrillation (AFib) is identified. Apple worked with the Food and Drug Administration (FDA) for a number of years to receive De Novo classification for the ECG app and the irregular heart rhythm notification, making the features available over the counter.

Available today as part of a free update to watchOS 5.1.2, the ECG app and irregular heart rhythm notification feature will help users identify signs of AFib, the most common form of irregular rhythm. When left untreated, AFib is one of the leading conditions that can result in stroke, the second most common cause of death around the world. The CDC estimates AFib can affect up to two percent of the younger population and nine percent of those 65 years and older in the US.

“Apple Watch has helped so many people around the world and we are humbled that it has become such an important part of our customers’ lives,” said Jeff Williams, Apple’s chief operating officer, in a statement. “With the release of these heart features, Apple Watch takes the next step in empowering people with more information about their health.”

“We are confident in the ability of these features to help users have more informed conversations with their physicians,” said Sumbul Desai, MD, Apple’s vice president of Health, in a statement. “With the ECG app and irregular rhythm notification feature, customers can now better understand aspects of their heart health in a more meaningful way.”


New electrodes built into the back crystal and Digital Crown on Apple Watch Series 4 work together with the ECG app to enable customers to take an ECG similar to a single-lead reading. To take an ECG recording at any time or following an irregular rhythm notification, users launch the new ECG app on Apple Watch Series 4 and hold 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. After 30 seconds, the heart rhythm is classified as either AFib, sinus rhythm or inconclusive. All recordings, their associated classifications and any noted symptoms are stored securely in the Health app on iPhone. Users can share a PDF of the results with physicians.

Touching the Apple Watch Series 4 Digital Crown completes the circuit and electrical signals across the heart are measured.
Touching the Apple Watch Series 4 Digital Crown completes the circuit and electrical signals across the heart are measured.

Irregular Rhythm Notification

Using the optical heart sensor in Apple Watch Series 1 or later, the irregular rhythm notification feature will occasionally check the user’s heart rhythm in the background for signs of an irregular heart rhythm that appears to be AFib and alerts the user with a notification if an irregular rhythm is detected on five rhythm checks over a minimum of 65 minutes.

“The role that technology plays in allowing patients to capture meaningful data about what’s happening with their heart, right when it’s happening, like the functionality of an on-demand ECG, could be significant in new clinical care models and shared decision making between people and their healthcare providers,” said Nancy Brown, CEO of the American Heart Association, in a statement. “At the American Heart Association, we are committed to educating and empowering people to be proactive in all areas of their heart health and general well-being.”

Apple Watch Series 1 or later with watchOS 5.1.2 sends a notification if an irregular heart rhythm such as AFib, is identified.
Apple Watch Series 1 or later with watchOS 5.1.2 sends a notification if an irregular heart rhythm such as AFib, is identified.

“The idea that wearables can be used by both patients and their health care providers to manage and improve heart health holds promise and should also be approached with caution to ensure information and data are used responsibly and in concert with other evidence-based tools and guidelines,” said C. Michael Valentine, MD, FACC, president of the American College of Cardiology, in a statement. “The ACC, through its focus on innovation, is committed to exploring ways that new technologies can optimize patient care and outcomes.”

The ECG app’s ability to accurately classify an ECG recording into AFib and sinus rhythm was validated in a clinical trial of around 600 participants. Rhythm classification from a gold standard 12-lead ECG by a cardiologist was compared to the rhythm classification of a simultaneously collected ECG from the ECG app. The study found the ECG app on Apple Watch demonstrated 98.3 percent sensitivity in classifying AFib and 99.6 percent specificity in classifying sinus rhythm in classifiable recordings. In the study, 87.8 percent of recordings could be classified by the ECG app.

The irregular rhythm notification feature was recently studied in the Apple Heart Study. With over 400,000 participants, the Apple Heart Study was the largest screening study on atrial fibrillation ever conducted, also making it one of the largest cardiovascular trials to date. A subset of the data from the Apple Heart Study was submitted to the FDA to support clearance of the irregular rhythm notification feature. In that sub-study, of the participants that received an irregular rhythm notification on their Apple Watch while simultaneously wearing an ECG patch, 80 percent showed AFib on the ECG patch and 98 percent showed AFib or other clinically relevant arrhythmias.

To enable these new heart features, customers will be taken through an onscreen setup flow that includes details about who can use these features, what the features can and cannot do, what results users may get, how to interpret those results and clear instructions for what to do if users are feeling symptoms that require immediate medical attention.

watchOS 5.1.2 will be available for download today.

Source: Apple Inc.

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  1. Unfortunately this function is limited to the USA on a hardware basis and is not available by changing the location settings on your iOS device as you can do with Apple News .
    I am a doctor in Canada fully trained to interpret 12 lead EKG’s and this is very disappointing . I understand the regulatory issues and know that we have to wait for Health Canada which always works at a glacial pace to approve this device and no doubt Apple has bigger fish to fry so is obeying regulatory restrictions , but this seems ridiculous to me . I was looking forward to fiddling around with this and if it works appropriately recommending it friends and patients .There has been a lot of hype about this being the first rhythm analysis capable device available to the consumer which it most certainly is not . In the meantime I will continue to recommend the AliveCor Kardia device , which I know works to those who need it .

  2. Just installed and took first ECG with the AW4. Works even easier than the Kardia Mobile device, which it is replacing. The trace looks just like the multi-lead ones I’ve been taking for the last 50 years. Yes, my dad was a cardiologist.

    In the past, I’ve often recommended the AliveCor Kardia Mobile device. It’s fantastic, and you can let others use it, as the device doesn’t have to be attached to the back of your iPhone. However, the AppleWatch4 ECG app is even more convenient for a single user.

      1. KenC, I am a CT surgeon in Canada and agree with your posts .The value of AW 4 is that it has both the optical Plethysmographic sensors which measure pulse rate and the EKG sensor which measure electrical heart rate (which is not always the same ).since you wear the watch continuously , in theory the optical sensor may be able to warn people of an abnormality when it happened and then a one lead EKG can be taken .This has value. the AliveCor Kardia requires one to do the EKG when the one has symptoms or simply wants the data .People should be aware that there are many reasons why people have an irregular heart rate other than AF and indeed heart rate variations related to respiration are completely normal and to be expected in young people and this variance persists in many people in to their 40’s . This is the reason that the medical community fears being inundated with completely healthy and normal people who fear an irregular HR

        1. Thank you BM for all that info. My dad was also a cardiologist in Canada before moving to the US. Anyhow, I think your comment about “fears being inundated” are a bit overblown. Isn’t it better to have a few more checkups of normal people, than to have people dying from untreated cardiac issues?

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