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
80 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
80 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
80 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
80 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
80 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
80 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

Provenance Emulator

PlayStation, GameCube, Wii, and SEGA Emulator for iPhone and Apple TV Coming to App Store

Friday April 19, 2024 8:29 am PDT by
The lead developer of the multi-emulator app Provenance has told iMore that his team is working towards releasing the app on the App Store, but he did not provide a timeframe. Provenance is a frontend for many existing emulators, and it would allow iPhone and Apple TV users to emulate games released for a wide variety of classic game consoles, including the original PlayStation, GameCube, Wii,...
Delta Feature

Delta Game Emulator Now Available From App Store on iPhone

Wednesday April 17, 2024 9:58 am PDT by
Game emulator apps have come and gone since Apple announced App Store support for them on April 5, but now popular game emulator Delta from developer Riley Testut is available for download. Testut is known as the developer behind GBA4iOS, an open-source emulator that was available for a brief time more than a decade ago. GBA4iOS led to Delta, an emulator that has been available outside of...
iPhone 15 Pro Action Button Translate

All iPhone 16 Models to Feature Action Button, But Usefulness Debated

Tuesday April 16, 2024 6:54 am PDT by
Last September, Apple's iPhone 15 Pro models debuted with a new customizable Action button, offering faster access to a handful of functions, as well as the ability to assign Shortcuts. Apple is poised to include the feature on all upcoming iPhone 16 models, so we asked iPhone 15 Pro users what their experience has been with the additional button so far. The Action button replaces the switch ...
iPad Air 12

12.9-Inch iPad Air Now Rumored to Feature Mini-LED Display

Thursday April 18, 2024 7:37 am PDT by
The rumored 12.9-inch iPad Air that is expected to be announced in May will be equipped with a mini-LED display like the current 12.9-inch iPad Pro, according to Ross Young, CEO of research firm Display Supply Chain Consultants. The existing 10.9-inch iPad Air is equipped with a standard LCD panel, and the move to mini-LED technology for the 12.9-inch model would provide increased brightness for...