Apple’s trying out something entirely new starting Thursday: a medical study.

The company has released a new app that will use the Apple Watch's heart-rate monitor to check for irregular heart rates as part of a study it's running with Stanford University. While others have used Apple's software and devices in medical studies, this is the first time that it’s actually sponsored one itself. The move is another sign that Apple is moving deeper into the health space.

“Working alongside the medical community, not only can we inform people of certain health conditions, we also hope to advance discoveries in heart science,” said Apple chief operating officer Jeff Williams, in a statement.

Health and fitness have been a key focus for Apple, especially since launching the Apple Watch two years ago. That has allowed the company to tap the $3 billion health care market and, analysts say, find new audiences for its products and services. Apple already employs a small staff of medical professionals to develop its health products, and it is reportedly working on a diabetes glucose-monitoring device that won’t pierce the skin. It's also worked with hospitals to include more of its tech in patients' rooms.

The new study takes all of that a step further: Now Apple itself will be running a study and submitting data to the Food and Drug Administration. The heart-rate researcher will look specifically at atrial fibrillation — or afib — which refers to an irregular heart rate and is a leading cause of stroke and other heart conditions. The condition kills around 130,000 people per year, according to estimates from the Centers for Disease Control and Prevention.

Users have to be over the age of 22 if they want to participate in the study. If the app detects an irregular heartbeat, it will notify that person on the Watch and iPhone. From there, he or she may opt to see a doctor online, for a free consult on their health. Apple and Stanford are partnering with Boston firm American Well to provide those consults.

The study, while promising, is not perfect, experts said.

For one, atrial fibrilation is generally more prevalent in older people and obese individuals, said Ron Blankstein, a cardiologist and associate professor at Harvard Medical School. That may not be the biggest users of the Apple Watch yet. Then there's the fact that not all irregular heartbeats are a sign of a serious condition, he said. The Watch's heart monitors are not as precise as clinical diagnostic tools. This could lead to overtreatment, he said.

Apple has previously noted how its products can make it easier for researchers to find study participants, thanks to their broad reach. Traditionally, researchers have had to seek out study participants directly — through medical facilities, by email or with fliers. Then, they often must visit them in person to collect data. By enrolling using devices, Apple has said, it makes it easier for scientists to both find and monitor study participants.

At least 33 million units of the Watch have been sold, according to Asymco analyst Horace Deidu  — Apple itself does not officially release sales figures, nor information on who is buying the Watch. But Apple researchers said they believe the Watch will provide a representative sample of the population for their study.

Apple declined to say how long the study will run and whether it would take on further research in the future.