At the just-concluded American College of Cardiology annual meeting in New Orleans, physicians were buzzing about Apple’s massive irregular heartbeat study. While it was widely accepted that more research is needed, many experts are also excited about the potential that the study represents.
In this exclusive MedPage Today video, Anne B. Curtis, MD, of the University at Buffalo’s Jacobs School of Medicine & Biomedical Sciences, and Roxana Mehran, MD, of Mount Sinai Hospital in New York City, discuss both the limitations of the study and the reasons to be excited.
Following is a transcript of their remarks:
Mehran: Very excited about the Apple Heart Study. In fact, I was wowed with the Apple Heart Study for many, many reasons. First of all, I have an Apple watch and I love my Apple watch. I had to think that those people who actually wear the Apple watch actually end up loving it, because in many, many ways, they can use it for a lot of other reasons other than the Apple Heart Study. That’s for sure.
Curtis: The Apple Heart Study was actually probably one of the largest studies ever done with over 400,000 participants. But it was a virtual study in that patients could sign up online and start working on the study without ever having to go into a doctor’s office for an initial screening visit or anything like that. The study was designed to test the algorithm that the Apple watch has on it for determining whether heart rate is irregular or not. If it detects that the heart rate is very irregular, that could be atrial fibrillation. The algorithm, then, repeats the checking every 15 minutes or so until it confirms five out of six times that the heart rate is irregular, and therefore could be atrial fibrillation. The idea is that the patient would be notified of that, advised to seek medical help, and the next step was to wear an EKG patch or monitor for about two weeks to see if you could confirm the diagnosis of atrial fibrillation. From there, the patients would be treated according to what the results were.
Mehran: What I loved at the clinical trial about the Apple Heart Study, 450 or 435,000 or 39,000 patients enrolled in eight months. It’s unconscionable. In fact, 1 in 600 U.S. adults were included in this study, and it was so inclusive and not exclusive. 42% women, Hispanics, Latinas, African Americans, well represented.
Curtis: Although, only about 25% of them were over the age of 65, which is the age group that would be most likely to have atrial fibrillation. There were an awful lot of young people who wouldn’t otherwise have problems. But out of the entire cohort, only 0.5% of them were diagnosed as having an irregular rhythm, but that jumped up to over 3% in that older age group.
Mehran: Okay, it was a young patient population. The predictive value was not great, and of course, it was a single-arm study, so we didn’t really test any kind of an intervention. I think what we did do, though, we opened the box. We opened Pandora’s Box. I think it’s going to be really exciting.
Curtis: Now when they went to correlate whether or not the algorithm correctly predicted atrial fibrillation, it wasn’t perfect. If a patient was wearing the EKG monitor at the same time that they were getting notification from the algorithm that there was a problem, the correlation was 84%. Good, but not 100%. On the other hand, if the patient got the notification and then wore a monitor later on, then the correlation fell to 71%. I’m not surprised about that because atrial fibrillation can come and go, and you’re only going to be able to diagnose it when it happens. That’s one take home I would have from that.
Mehran: Of course, I was, again, not wowed by the low-positive predictive value. I think they had a very healthy patient population, and furthermore, when they dissected it into the age greater than 65 and with a patch, they were able to increase the positive predictive value which tells you that you can increase precision if you actually study the right patient population.
Curtis: The other interesting thing is for all of the interest people had being in the study, many of them, when they were notified that they could have a problem, actually didn’t follow up with their doctors. We made the diagnosis, but they didn’t do anything about it. We have to figure out ways to not only pick up these things in health apps, but also get patients the correct treatment.
Then finally the last thing I would say about this is even if we do diagnose atrial fibrillation early, what we still have to prove is whether it makes a difference. When a patient has symptomatic atrial fibrillation, we know we need to treat it. We have a pretty good idea the parameters by which we would anticoagulate a patient, but for somebody who has episodes that are asymptomatic and have not been detected yet, will it have the same effect on cardiovascular outcomes by treating those patients as much as others? That remains to be seen.
Mehran: I think this is the beginning of the future. It’s great.