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A highly anticipated heart study of the Apple Watch is facing disruptions as a result of the coronavirus pandemic, with enrollment slowing down and both retail store restrictions and social distancing measures interfering with a novel plan for seniors to obtain the devices.

But, as the pandemic stretches on, the study could also become a test case for the opportunities of clinical research conducted remotely — both during the crisis and after it has passed.

The Heartline Study, launched by Apple and Johnson & Johnson, aims to follow seniors — some of whom may have an undetected heart problem known as atrial fibrillation — to see what happens when they wear an Apple Watch or receive health tips delivered via iPhone.


The study opened the last Tuesday in February. In its first week, it signed up about 5,000 people, a strong start toward the study’s ambitious goal of enrolling 150,000 Americans over the age of 65.

Then the coronavirus crisis exploded.


Along with slowing down enrollment, the virus is also certain to interfere, perhaps for months, with the unique distribution model that the study’s designers dreamed up: Seniors out shopping would have the option to go to their local Best Buy to pick up an Apple Watch, which they could borrow or buy at a steep discount, if they were assigned to wear it as part of the trial.

Now, health officials have urged older Americans — the exact population the study is trying to enroll — to stay in their homes for an indefinite period. Best Buy stores have cut back their hours; on Monday, they will start limiting foot traffic to no more than 15 customers at once.

Despite the unforeseen obstacles, Heartline — like other fully remote studies — has significant advantages over other trials. There are no doctor’s office visits. There are no drug infusions. Enrollees assigned to get an Apple Watch can still order one from Best Buy’s website. Once they have it, they can participate in the study entirely from their homes for the two years over which they’ll be actively in the program.

That may be a public health necessity if, as some experts have warned, communities around the globe may need to follow strict social distancing measures for 18 months or more until a vaccine is developed and tested.

“People can do this from isolation, from the comfort of their home. They can enroll in the study, they can do all of their participation activities simply at home,” said Paul Burton, head of cardiovascular and metabolic medical affairs at Johnson & Johnson’s Janssen unit.

“In times like this, a study like Heartline really does come into its own,” he said.

Drug makers at large are bracing for a massive slowdown of many of their clinical studies, particularly those requiring frail patients to come in for infusions and other regular appointments at major hospitals that may soon be inundated with contagious Covid-19 patients. Over the past few days, companies including Addex Therapeutics, Arrowhead Pharmaceuticals, and Provention Bio have announced that they’ve halted trials. More are expected in the days to come.

By contrast, there are no plans to change the timeline of Heartline, Burton said.

Apple and Johnson & Johnson were not expecting a pandemic when, over three years ago, they teamed up for the first time to start talking about the study that would become Heartline.

Back then, Apple was gearing up to launch the Apple Heart Study, its first big virtual study of its smartwatch. That trial enrolled more than 400,000 people and found that the Apple Watch could safely detect heart rate irregularities that further testing confirmed as A-fib. (The condition can lead to strokes, heart failure, and other serious complications.) Those study results, which were presented a year ago at a big cardiology meeting, helped Apple win clearance from the Food and Drug Administration to alert people who may be at risk for A-fib, though some cardiologists still question the watch’s clinical utility.

For Apple, Heartline offered an opportunity to build on the heart study.

For its part, Johnson & Johnson had a strong interest in stroke prevention, Burton said. The company also wanted to find new ways to help improve adherence to its blood thinners, which it markets for people with A-fib and other conditions. (Johnson & Johnson is the study’s sponsor, while Apple is a collaborator on the study.)

From the beginning, Heartline was imagined as a way to make it easier for people to participate in clinical research. “You don’t have to be a resident in a major city or near a large medical center to be able to participate. You can be in any town or you can live anywhere around the country,” Burton said.

The researchers also wanted to make sure they weren’t just enrolling wealthy people who could afford an Apple Watch, which goes for $400. The study is subsidizing the cost of the watch so that participants can buy it for $49, or get it on loan for no cost.

The study has two cohorts. Within each cohort, participants will be randomly assigned to one of two groups. One group will be assigned to wear an Apple Watch and participate in an educational program delivered via app involving reminders and educational content; those in the other group will use the app on their iPhones but not get Apple Watches.

One cohort will enroll people who have not been diagnosed with A-fib. The app will send them tips about heart health in general. For this cohort, the primary goal of the study will be to see if the digital interventions are associated with a quicker diagnosis for enrollees with undetected A-fib. That will be assessed using insurance claims data. (Participants have to agree to share this information with researchers in order to enroll.)

The other cohort will enroll people who have already been diagnosed with A-fib. These patients are generally on blood thinners to prevent the blood clots that can cause strokes; the app will send them tips about adhering to their medication. For this cohort, the primary goal of the study will be to see if the interventions are associated with an increased percentage of days in which patients fill and refill their medicines as prescribed.

As secondary endpoints — goals for which the study is not specifically powered to answer but can still generate useful signal — the trial will also look at whether enrollees have strokes, heart attacks, and blood clots while they’re getting the digital interventions and in the months after.

The study plans to continue enrolling patients over the next year or so. If the trial approaches its enrollment goal — far from guaranteed during a crisis in which seniors have many other concerns and priorities at top of mind — it will be the largest randomized cardiovascular trial ever, according to Burton.

For now, enrollees “don’t want to go out and pick up the watch,” Burton said. As of Wednesday, seniors were still technically able to pick up Apple Watches and learn about the study at Best Buy locations that remain open, Burton said. (Best Buy did not return STAT’s request for comment.)

Burton described the enrollment slowdown brought on by the pandemic as “modest.” He said he expects the slowdown to extend over the next few weeks but he’s hopeful that enrollment will pick back up some time after that.

There’s reason to think that may happen. “People want an alternative. They basically want to be distracted,” said Ethan Weiss, a cardiologist at the University of California, San Francisco, who has no involvement with Heartline. “There almost is an increase in interest in participating in a clinical trial or something like that, because it gives people something else to do and think about — and not worry about getting infected with the virus all the time.”

At the same time, Weiss said, there are questions around how engaged participants will be — and how applicable that engagement will be after the pandemic is over.

If everything goes according to plan, the study will report its full results in 2024.