Apple Watch heart rate study

Apple made waves this fall when it announced that the FDA approved its two new heart rate sensing systems. Now, the team behind the data that convinced the FDA to approve Apple technology is giving the rest of the world a peek into how they did it, laying the blueprint for the next generation of wearables that may follow.

In September, we found out which two Apple heart sensing technologies passed the FDA’s sniff test: The hardware on the Series 4 watch and the software that can detect heart rate (it works on the Apple Watch Series 1 and beyond.)

On Thursday, we learned how the software convinced the FDA of its accuracy, because the researchers behind the Apple Heart Study, which tested the software on 419,093 Apple Watch users released their methods in The American Heart Journal.

Dr. Peter Kowey, a a cardiologist at Mainline Health’s Lankenau Heart Institute who is also on the study’s steering committee, tells Inverse that the study represents a massive step forward:

“This is a landmark trial,” Kowey says. “Not so much because of this one particular niche arrhythmia that we’re looking for, although it’s a common arrhythmia. That’s just the beginning. What we’re looking for are future ways of looking to monitor patients.”

In the brief history of wearable consumer technology, there have been very few devices that the FDA sees fit to approve as a medical device. One of them was Alivecor’s wrist strap that launched in 2017. But Apple is arguably the first major brand to obtain FDA approval because of the power of the evidence from this clinical trial. We still don’t actually have the results of this trial — though Kowey adds that it might happen within the next two months. The study just tells us the story of the research that convinced the FDA.

Tim Cook introduces the Apple Watch series four, describing its FDA approved EKG

This study investigated whether the Apple watch’s wrist-based heart rate monitor might be up to the challenge of detecting atrial fibrillation — a heart condition that plagues between 2.1 and 6.7 million Americans by the CDC’s estimate.

In short, hundreds of thousands of Apple Watch users opted into the study online and downloaded a specific algorithm onto their watches that was trained to look for AFib. If the algorithm flagged something, the user received a push notification, was contacted by a study doctor, and then received a patch — a traditional way of detecting AFib. The results of the study will investigate whether the data collected by that patch matches the data collected by the watch.

apple heart rate study
A screenshot from the Apple Heart Rate Study 

While we wait on that analysis, Kowey adds that he feels confident that the results will be positive.

“The FDA was willing to act on more preliminary data when they had the announcement of the approval of the device last month, but we haven’t seen the validation yet,” he says. “I think it’s going to be validated. That’s my opinion.”

If that happens, he anticipates that other companies might use this study design to investigate other types of heart diseases. Applications he sees coming down the pipe include detection of certain lung conditions or other types of heart disease.

But the significance of this paper, he says, is that it adds a layer of transparency to the science behind these devices. Evaluating methods is a central part of the peer-review process, which is how studies end up in accredited journals. Releasing the methods ahead of the results should theoretically allow heart experts throughout the field to take a look at the results and interpret them ahead of time as they await the final verdict.

“When the published report comes out, then people will see what’s being done. It’s a peer-review paper. It’s a very important part of the puzzle,” adds Kowey.

Photos via American Heart Journal , Giphy