Study Confirms Apple Watch Can Detect Abnormal Heart Rhythm With 97% Accuracy

The heart rate monitors built into the Apple Watch and other wearable devices can detect abnormal heart rhythms with 97 percent accuracy, according to a new study conducted by the team behind the Cardiogram app for Apple Watch in conjunction with researchers at the University of California, San Francisco.

More than 139 million heart rate and step count measurements were collected from 9,750 users of the Cardiogram app who also enrolled in the UC San Francisco Health eHeart Study, with the data used to train DeepHeart, Cardiogram's deep neural network.

cardiogram
Once trained, DeepHeart was able to read heart rate data collected by wearables, distinguishing between normal heart rhythm and atrial fibrillation with a 97 percent accuracy rate, both when testing UCSF patients with known heart issues and Cardiogram participants.

At a 97 percent accuracy rate, Cardiogram's study suggests the Apple Watch alone does a better job of detecting abnormal heart rhythms than FDA-approved accessory KardiaBand. From Cardiogram co-founder Johnson Hsieh:

97% accuracy refers to the c-statistic, or area under the sensitivity-specificity curve. Surprisingly, both the sensitivity and specificity of DeepHeart were even higher than an FDA-cleared Apple Watch ECG attachment -- 98% (vs 93%) sensitivity and 90% (vs 84%) specificity.

Published in JAMA Cardiology this morning, the study confirms the results from a similar preliminary study done in May of 2017. According to Cardiogram, today's study marks the first peer-reviewed study in a medical journal that demonstrates popular wearables from companies like Apple, Garmin, Polar, LG, and others can detect a major health condition.

Atrial fibrillation, or an abnormal heart rhythm, is a condition that can be indicative of major health problems and it can lead to heart failure and stroke. Atrial fibrillation often goes undiagnosed, which is where the Apple Watch and other wearables can help. The Apple Watch won't replace a traditional EKG, but it can alert people to a problem much earlier than it might otherwise be detected. From the study's conclusion:

This proof-of-concept study found that smartwatch photoplethysmography coupled with a deep neural network can passively detect AF but with some loss of sensitivity and specificity against a criterion-standard ECG. Further studies will help identify the optimal role for smartwatch-guided rhythm assessment.

In addition to studies on the Apple Watch's ability to detect atrial fibrillation, Cardiogram and UCSF have also been working to determine if the Apple Watch heart rate monitor can also detect conditions like hypertension, sleep apnea, and early signs of diabetes. Preliminary studies have suggested all of these conditions could be spotted in data collected by Apple Watch and other common wearable devices.

Apple has been working with researchers at Stanford on its own study to determine whether the heart rate sensor in the Apple Watch can be used to detect abnormal heart rhythms and common heart conditions. While in the study, if an abnormal heart rhythm is detected, participants will be contacted by researchers and asked to wear an ePath monitor to test heart health.

Apple Watch owners can sign up to participate in the Apple Heart Study by downloading and installing the Apple Heart Study app. Those who want to join Cardiogram's studies can install the Cardiogram app and sign up to join the mRhythm study.

Related Roundup: Apple Watch Series 9
Buyer's Guide: Apple Watch (Neutral)

Top Rated Comments

justperry Avatar
79 months ago
Another paid research. It's the same off-the-shelf HRM as other watches.
Seems like you can't read, there are other brands mentioned/involved in the article, like LG and Polar amongst others.

(Macrumors) today's study marks the first peer-reviewed study in a medical journal that demonstrates popular wearables from companies like Apple, Garmin, Polar, LG, and others can detect a major health condition.
Why so negative, I think this is a good thing.
Score: 21 Votes (Like | Disagree)
370zulu Avatar
79 months ago
My AW3 is a requirement by my wife after my heart attack a while back. I wear it while I sleep and have it set to alert me if my HR goes above 120. When I was ill and had a fever, my HR went up and over 120 a few times and I had the watch wake me while I was trying to rest. This does make wife and I feel better about having some kind of warning that I may need to seek medical attention.

For that, the price of AW3 is definitely worth it for me despite the naysayers.
Score: 11 Votes (Like | Disagree)
Cesar Battistini Avatar
79 months ago
Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
Is the watch tight enough? That usually solves the problem.
Score: 8 Votes (Like | Disagree)
oneMadRssn Avatar
79 months ago
I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
Score: 7 Votes (Like | Disagree)
NinjaHERO Avatar
79 months ago
Very cool. I look forward to the day my tech can tell the doctors what I've broken. :-)
Score: 7 Votes (Like | Disagree)
citysnaps Avatar
79 months ago
My AW3 is a requirement by my wife after my heart attack a while back. I wear it while I sleep and have it set to alert me if my HR goes above 120. When I was ill and had a fever, my HR went up and over 120 a few times and I had the watch wake me while I was trying to rest. This does make wife and I feel better about having some kind of warning that I may need to seek medical attention.

For that, the price of AW3 is definitely worth it for me despite the naysayers.
That's a great story. Thanks for sharing!
Score: 5 Votes (Like | Disagree)

Popular Stories

reset password request iphone

Warning: Apple Users Targeted in Phishing Attack Involving Rapid Password Reset Requests

Tuesday March 26, 2024 4:34 pm PDT by
Phishing attacks taking advantage of Apple's password reset feature have become increasingly common, according to a report from KrebsOnSecurity. Multiple Apple users have been targeted in an attack that bombards them with an endless stream of notifications or multi-factor authentication (MFA) messages in an attempt to cause panic so they'll respond favorably to social engineering. An...
Generic iOS 18 Feature Purple

iOS 18: What to Expect From 'Biggest' Update in iPhone's History

Wednesday March 27, 2024 11:10 am PDT by
At least some Apple software engineers continue to believe that iOS 18 will be the "biggest" update in the iPhone's history, according to Bloomberg's Mark Gurman. Below, we recap rumored features and changes for the iPhone. "The iOS 18 update is expected to be the most ambitious overhaul of the iPhone's software in its history, according to people working on the upgrade," wrote Gurman, in a r...
maxresdefault

Apple to Launch New iPad Pro and iPad Air Models in May

Thursday March 28, 2024 11:07 am PDT by
Apple will introduce new iPad Pro and iPad Air models in early May, according to Bloomberg's Mark Gurman. Gurman previously suggested the new iPads would come out in March, and then April, but the timeline has been pushed back once again. Subscribe to the MacRumors YouTube channel for more videos. Apple is working on updates to both the iPad Pro and iPad Air models. The iPad Pro models will...
maxresdefault

Apple Announces WWDC 2024 Event for June 10 to 14

Tuesday March 26, 2024 10:02 am PDT by
Apple today announced that its 35th annual Worldwide Developers Conference is set to take place from Monday, June 10 to Friday, June 14. As with WWDC events since 2020, WWDC 2024 will be an online event that is open to all developers at no cost. Subscribe to the MacRumors YouTube channel for more videos. WWDC 2024 will include online sessions and labs so that developers can learn about new...
apple maps 3d feature

Apple Maps May Gain Custom Routes With iOS 18

Tuesday March 26, 2024 3:10 pm PDT by
Apple may be planning to add support for "custom routes" in Apple Maps in iOS 18, according to code reviewed by MacRumors. Apple Maps does not currently offer a way to input self-selected routes, with Maps users limited to Apple's pre-selected options, but that may change in iOS 18. Apple has pushed an iOS 18 file to its maps backend labeled "CustomRouteCreation." While not much is revealed...
General iOS 17 Feature Orange Purple

Apple Releases Revised Versions of iOS 17.4.1 and iPadOS 17.4.1 With Updated Build Number

Wednesday March 27, 2024 5:59 am PDT by
Apple on late Tuesday released revised versions of iOS 17.4.1 and iPadOS 17.4.1 with an updated build number of 21E237, according to MacRumors contributor Aaron Perris. The updates previously had a build number of 21E236. The revised updates are available for all iPhone and iPad models that are compatible with iOS 17 and iPadOS 17, but they can only be installed via the Finder app on macOS...
applephilschiller

Apple's Phil Schiller Works 80 Hours a Week Overseeing App Store

Wednesday March 27, 2024 2:03 pm PDT by
With the App Store and app ecosystem undergoing major changes in the European Union, The Wall Street Journal today shared a profile on App Store chief Phil Schiller, who is responsible for the App Store. Though Schiller transitioned from marketing chief to "Apple Fellow" in 2020 to take a step back from Apple and spend more time on personal projects and friends, he is reportedly working...