New York CNN Business  — 

Apple is partnering with Johnson & Johnson to reduce the risk of strokes in senior citizens.

J&J (JNJ) and Apple (AAPL) announced Tuesday that US citizens over the age of 65 (with a traditional Medicare plan) will be eligible to participate in clinical research through the Heartline Study app on iPhones. They’ll also have access to heart health features on Apple (AAPL) Watch models. The patients must also agree to provide access to their Medicare claims data.

“Heartline could go down as a landmark clinical trial. We are bringing amazing digital wearable tech and engagement apps for healthcare to patients and doctors,” said Dr. Paul Burton, vice president of medical affairs for J&J’s Janssen Pharmaceutical Companies unit, in an interview with CNN Business.

The study is designed to detect atrial fibrillation or AFib, an irregular heart rhythm that is a leading cause of stroke.

“AFib can potentially lead to more strokes for people over the age of 65. Cases are more common,” Burton said. “And people fear having a stroke as much as dying.”

Burton said that enrollment for the study is now open and that patients will be studied for at least two years. Participants need to already own an iPhone 6s or a later model. He added that one group of patients will be tracked only on their phones and another group will receive an Apple Watch that will feature an ECG app and irregular rhythm notification feature.

The J&J-Apple announcement is the latest in a partnership between the two companies. They first announced plans to work together on an AFib detection study in January 2019.

Apple has been promoting the Apple Watch as a device that can help people keep track of vital medical information, most notably their heart rate.

“The Heartline Study will help further understanding of how our technology could both contribute to science and help improve health outcomes, including reducing the risk of stroke,” Myoung Cha, Apple’s head of health strategic initiatives, in a statement Tuesday.