Stanford Medicine has published more details about the future of the Heart Study program it conducted in partnership with Apple, in which it attempted to reliably detect atrial fibrillation in Apple Watch wearers.

The condition, which is characterized by an irregular heartbeat, often remains hidden because many people don't experience symptoms. Atrial fibrillation can increase the risk of stroke and heart failure.

apple heart study
According to Stanford, the study involved 400,000 participants, making it the largest screening program for atrial fibrillation ever conducted. A paper has also been published in the American Heart Journal describing the unique design of the clinical trial.

Enrollment began in late 2017 and closed in August. Although some participants were informed in September that their participation in the study was complete, Stanford says it will continue to collect and collate data until early next year, which is consistent with Apple's original announcement.

"We hope this study will help us better understand how wearable technologies can inform precision health," said Lloyd Minor, MD, dean of the School of Medicine. "These new tools, which have the potential to predict, prevent and manage disease, are finally within our reach."

The FDA cleared two Apple Watch medical apps in September. One app uses data from the Apple Watch Series 4 to take an ECG by touching the button on the side of the device. The second app uses data from an optical sensor available on the Apple Watch Series 1 and later to analyze pulse data and identify irregular heart rhythms indicating atrial fibrillation. The Apple-Stanford Heart Study used the second app.

Each year in the United States alone, atrial fibrillation results in 130,000 deaths and 750,000 hospitalizations, according to the Centers for Disease Control and Prevention. The CDC estimates that the condition affects between 2.7 million and 6.1 million people. In addition, another 700,000 people may have undiagnosed atrial fibrillation.

Top Rated Comments

Veinticinco Avatar
92 months ago
Even though cardiology isn’t my field, it will be very interesting to see the first data analysis.
[doublepost=1541159489][/doublepost]Far from being a niche product, the AW’s health monitoring potential is seismic. Blood glucose monitoring would be the next hurdle and game-changer.
Score: 6 Votes (Like | Disagree)
centauratlas Avatar
92 months ago
Even though cardiology isn’t my field, it will be very interesting to see the first data analysis.
[doublepost=1541159489][/doublepost]Far from being a niche product, the AW’s health monitoring potential is seismic. Blood glucose monitoring would be the next hurdle and game-changer.
Other game changers:
1. Using the optical sensor (perhaps an improved version) to monitor blood oxygen saturation.
2. Continuous body temperature monitoring. Your watch could know that your "normal" body temperature is 98.2 in the morning and 98.9 in the afternoon or whatever. You'd have months/years of data to say, okay, my temp is 0.4 above normal right now, perhaps I should go to bed earlier so that when I am sick in the morning, I'll be well rested.
...and many more.

While in many controlled cases these are done (e.g. hospitals) I don't believe there have been any long term studies of large groups (e.g. 400,000 people!) where this data is collected. You might see a slight spike (e.g. a tenth of a degree) in temperature a day or two before a cold or flu hits. Or you might see a drop in oxygen sat level by 1% or 2% days before pneumonia is visible on an x-ray.

With half a million people, this type of information could become visible in the data and could then be used going forward.

There are many other uses where continuous data (or even 12-18 hours a day) monitoring can provide important information for doctors and consequently patients.

One hopes the FDA (and equivalent agencies around the world) don't stand in the way of out-of-the-box uses.
Score: 3 Votes (Like | Disagree)
bbednarz Avatar
92 months ago
This is absolutely amazing that Apple hasn’t moved this from a fashion accessory to a true health and fitness device
This has been pitched as a health and fitness device since the Series 2 debuted. The original watch was the only one that was really mainly focused on the fashion side. They changed course since then and now the main thing they pitch is health and fitness. Elevated heart rate notifications, EKG, fall detection, closing your rings: these are the main things they talk about when discussing the watch. It still has some fashion in it with the different casings and bands, but all of the functions of the watch are still present in all casing options.
Score: 3 Votes (Like | Disagree)
keysofanxiety Avatar
92 months ago
That is a massive study. You can tell Apple are taking this seriously.

I’ve only had my Apple Watch for less than a fortnight and I can already tell how often I’ll be using it.
Score: 2 Votes (Like | Disagree)
velocityg4 Avatar
92 months ago
That is a massive study. You can tell Apple are taking this seriously.

I’ve only had my Apple Watch for less than a fortnight and I can already tell how often I’ll be using it.
Of course they would. Just think of the sales boon if these were recommended by doctors and covered by health insurance/government healthcare around the world. Perhaps make a much more advanced $50,000 model for use in hospitals for patient monitoring and diagnostics.
Score: 1 Votes (Like | Disagree)

Popular Stories

Apple Shopping Event 2025

Apple Announces 2025 Black Friday Event, Here's What You Can Get

Thursday November 20, 2025 6:28 am PST by
Apple's annual four-day Black Friday through Cyber Monday shopping event is returning on Friday, November 28 through Monday, December 1 in many countries, including the United States, Canada, Australia, New Zealand, France, Germany, Italy, Spain, the United Kingdom, Belgium, the Netherlands, Sweden, Thailand, and others. During the shopping event, customers can get an Apple gift card with...
iPhone 17 Pro Cosmic Orange

10 Reasons to Wait for Next Year's iPhone 18 Pro

Wednesday November 19, 2025 4:00 am PST by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
iOS 26

Everything New in iOS 26.2 Beta 3

Monday November 17, 2025 3:20 pm PST by
Apple provided developers with the third beta of an upcoming iOS 26.2 update, and there are still new features that are being added with each beta that we get. We've rounded up all of the changes that Apple made in beta 3. AirDrop Apple added new AirDrop functionality, providing a way for two people to share files temporarily without having to add one another as contacts. iOS 26.2...
applecare apple care banner

Apple Brings New AppleCare+ Options to India

Tuesday November 18, 2025 8:42 am PST by
Apple today announced an expansion of AppleCare+ coverage in India, with new options for monthly and annual plans, and the addition of Theft and Loss for iPhone for the first time. Options for monthly and annual AppleCare+ plans in India provide more choice and flexibility, allowing users to keep coverage for as long as they require. Apple's vice president of Worldwide iPhone Product...
ipad mini 7 feature red and blue

iPad Mini 8: Four Major New Features to Expect

Wednesday November 19, 2025 7:50 am PST by
Apple's eighth-generation iPad mini is highly likely to arrive next year, offering a significant refresh of the device with at least four major new features. OLED Display The next-generation version of the iPad mini could feature an OLED display, as part of Apple's plan to expand the display technology across many more of its devices. Apple's first OLED device was the Apple Watch in 2015, ...
iPhone 17 Pro and Air N1 Feature

iPhone 17 vs. iPhone 16 Wi-Fi Speeds: New Study Reveals the Winner

Tuesday November 18, 2025 10:53 am PST by
A new study has revealed that the iPhone 17, iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air achieve significantly faster average Wi-Fi speeds compared to the iPhone 16 series, thanks to Apple's custom-designed N1 chip. The study was conducted by Ookla, the company behind the popular Speedtest website and app. It said the results are based on global, crowdsourced Speedtest user data...
Apple Wallet ID Illinois

iPhone Driver's License Feature Launching in Illinois

Tuesday November 18, 2025 8:47 am PST by
In select U.S. states, residents can add their driver's license or state ID to the Wallet app on the iPhone and Apple Watch, providing a convenient and contactless way to display proof of identity or age at select airports and businesses, and in select apps. Starting this Wednesday, November 19, the feature will be available to residents of Illinois. The announcement confirmed that the...
macbook black friday

The Best Early Black Friday Mac Deals

Tuesday November 18, 2025 7:32 am PST by
We're getting closer to Black Friday, which lands next week on Friday, November 28. In the lead-up to the shopping holiday, we're tracking a few lowest-ever prices on Apple's most popular Macs, including the M4 MacBook Air and brand new M5 MacBook Pro. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment,...
iOS 26

iOS 26.2 Adds These New Features to Your iPhone

Thursday November 20, 2025 10:50 am PST by
iOS 26.2 is currently in beta testing. The upcoming update includes a handful of new features and changes on the iPhone, including a new Liquid Glass slider for the Lock Screen's clock, offline lyrics for Apple Music, and more. In a recent press release, Apple confirmed that iOS 26.2 will be released to all users in December, but it did not provide a specific release date. Keep reading...
Magic Keyboard Touch ID Feature

Apple Releases New Firmware for 140W USB-C Power Adapter, Magic Keyboard and Magic Trackpad

Tuesday November 18, 2025 1:05 pm PST by
Apple today released updated firmware for several accessories, including the 140W USB-C Power Adapter, the Magic Trackpad 2, the Magic Trackpad USB-C, the Magic Keyboard with Touch ID, and the Magic Keyboard with Touch ID and Numeric Keypad. There is no word on what's included in the updated firmware at this time, but it could offer performance improvements and security updates. Accessory...