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

AirPods Pro Firmware Feature

Apple Releases New Firmware for AirPods Pro 2, AirPods Pro 3, and AirPods 4

Thursday November 13, 2025 11:35 am PST by
Apple today released new firmware designed for the AirPods Pro 3, the AirPods 4, and the prior-generation AirPods Pro 2. The AirPods Pro 3 firmware is 8B25, while the AirPods Pro 2 and AirPods 4 firmware is 8B21, all up from the prior 8A358 firmware released in October. There's no word on what's include in the updated firmware, but the AirPods Pro 2, AirPods 4 with ANC, and AirPods Pro 3...
CarPlay Pinned Messages

iOS 26.2 Adds New CarPlay Setting

Thursday November 13, 2025 6:48 am PST by
iOS 26 extended pinned conversations in the Messages app to CarPlay, for quick access to your most frequent chats. However, some drivers may prefer the classic view with a list of individual conversations only, and Apple now lets users choose. Apple released the second beta of iOS 26.2 this week, and it introduces a new CarPlay setting for turning off pinned conversations in the Messages...
iPhone Pocket Short

iPhone Pocket Now Available to Order, But Already Selling Out

Friday November 14, 2025 6:20 am PST by
Apple recently teamed up with Japanese fashion brand ISSEY MIYAKE to create the iPhone Pocket, a limited-edition knitted accessory designed to carry an iPhone. iPhone Pocket is available to order on Apple's online store starting today, in the United States, France, China, Italy, Japan, Singapore, South Korea, and the United Kingdom. However, it is already completely sold out in the United...
tvOS 26 Profiles

tvOS 26.2 Adds a Useful New Feature to Your Apple TV

Friday November 14, 2025 10:02 am PST by
Starting with the upcoming tvOS 26.2 update, currently in beta, additional profiles created on the Apple TV no longer require their own Apple Account. In the Settings app on the Apple TV, under Profiles and Accounts, anyone can create a new profile by simply entering a name and indicating whether the profile is for a kid. The profile will be associated with the primary user's Apple Account,...
Tim Cook WWDC 2018

Report: Tim Cook to Step Down as Apple CEO 'as Soon as Next Year'

Saturday November 15, 2025 2:40 pm PST by
Apple is preparing for Tim Cook to step down as CEO of the company "as soon as next year," according to the Financial Times. The company's board of directors and senior executives "recently intensified preparations for Cook to hand over the reins," the report said. While the report said that Apple is unlikely to name a new CEO before its next earnings report in late January, it went on to ...
apple silicon mac lineup 2024 feature purple m5

Apple's 2026 Mac Plans

Friday November 14, 2025 3:23 pm PST by
Most of Apple's Macs are slated to get M5 chips across 2026, and there's a possibility we'll even see the first M6 chips toward the end of the year. Updates are planned for everything from the MacBook Air to the Mac Studio. MacBook Air (Early 2026) The MacBook Air will be one of the first Macs to get a 2026 refresh, with an update planned for the first few months of the year. The MacBook...
walmart new ornametns

Walmart Black Friday Deals Begin Today With Low Prices on Headphones, TVs, and More

Friday November 14, 2025 7:55 am PST by
Walmart's Black Friday sale has officially kicked off today, with an online shopping event that's also seeing some matching deals in retail locations. There are quite a few major discounts in this sale, including savings on headphones, TVs, and more. Note: MacRumors is an affiliate partner with Walmart. When you click a link and make a purchase, we may receive a small payment, which helps us...
best early black friday deals

Best Black Friday Apple Deals Live Now - Save on AirPods, iPads, and Apple Watches

Saturday November 15, 2025 1:45 pm PST by
We're officially in the month of Black Friday, which will take place on Friday, November 28 in 2025. As always, this will be the best time of the year to shop for great deals, including popular Apple products like AirPods, iPad, Apple Watch, and more. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When ...
iOS 26

iOS 26.2 Available Next Month With These 8 New Features

Tuesday November 11, 2025 9:48 am PST by
Apple released the first iOS 26.2 beta last week. 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 in 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....
homepod mini thumb feature

New HomePod Mini, Apple TV, and AirTag Were Expected This Year — Where Are They?

Wednesday November 12, 2025 11:42 am PST by
While it was rumored that Apple planned to release new versions of the HomePod mini, Apple TV, and AirTag this year, it is no longer clear if that will still happen. Back in January, Bloomberg's Mark Gurman said Apple planned to release new HomePod mini and Apple TV models "toward the end of the year," while he at one point expected a new AirTag to launch "around the middle of 2025." Yet,...