Wearables and Smartphones--Compliance in Atrial Fibrillation Monitoring

Discussion With Bradley Knight, MD, and Rod Passman, MD

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Interview by Jodie Elrod

Bradley Knight, MD, talks with Rod Passman, MD, about his presentation entitled “Wearables and Smartphones—Compliance in Atrial Fibrillation Monitoring” at Western AF 2025.

Bradley Knight, MD: Hi, I'm Dr Brad Knight, an electrophysiologist at Northwestern Medicine. I am also the editor-in-chief of EP Lab Digest and have been doing that for over 15 years now. As many of you know, HMP Global has partnered with the Western AFib Symposium. We're very excited to be involved with Western AFib, which I've been attending since the very beginning. It's an outstanding meeting. It's been great to be able to support it and to learn from the meeting every year. 

I am excited to be joined by my colleague and friend for the past 15 years at Northwestern, Dr Rod Passman. He is an endowed professor of medicine at Northwestern and the medical director of our AFib program. He is also the director of the Center for Arrhythmia Research at Northwestern. Rod, welcome and thanks for joining us. I attended your session earlier this morning. You gave a talk on wearables in remote monitoring compliance with AFib monitoring. Maybe we could start with having you give me some of the highlights of your talk. 

Rod Passman, MD: Sure. First of all, I think that we're in an incredible position as electrophysiologists because there is all this amazing consumer digital health technology available that can detect AFib, tell you whether you have it or not, and tell you how much you have. I think that the challenge for us is how to integrate this into our practice, how to integrate this into our research, and what our expectations are for our patients in terms of compliance. That's what I was talking about today. 

Bradley Knight, MD: I can give you some case examples. I see patients a lot in clinic who come for their first meeting because of a recent episode of AFib. The logical thing to do would be to monitor them for future recurrences. Many patients already have an Apple Watch. I'll notice they have an Apple watch, and I'll ask them if they know about the capabilities of the watch. Many know that there is a way to detect AFib, but that they can also record an electrogram. So, starting with the Apple product, how does someone use the watch? What should they do when they are first detected with AFib? 

Rod Passman, MD: First, you must turn these features on. They do not come turned on. I have what I refer to as a Genius Bar in my EP clinic where I'm showing patients how to turn on the irregular rhythm notification, which is meant as a screening tool. It checks the pulse every 2 hours or so and will alert the individual if they're having a prolonged episode of an irregular rhythm. These days, the patient can record the ECG on their watch. So, that's really meant for patients with no known history of AFib. It is geared more towards specificity, and again, as a screening tool. The other algorithm is the AFib history algorithm, which is meant to quantify the burden of AFib. That needs to be turned on as well. By the way, you need to lie to your watch. If you say that you have a history of AFib, it won't turn on the irregular notification, and vice versa. So, you must adjust it for the patient. The AFib history checks the pulse every 15 minutes or so, and then every Monday morning, it will tell you what percentage of the pulse checks was irregular. For some patients, I want them to be alerted in real time. For other patients, I want to know the burden and this needs to be customized, but it must be turned on. But you’re right, many patients don't know they're wearing a monitor. 

Bradley Knight, MD: Our hospital is in downtown Chicago, where a lot of patients have an iPhone or Apple Watch, but you showed some interesting data that correlated the socioeconomic status in the Chicagoland area with the type of phone they had, whether it's an Android or Apple product. Can you share some of that data? 

Rod Passman, MD: Yes, I started the talk by saying how wonderful this technology is, but I think that there are some companies that have done a better job than others. The most commonly used watch is the Apple Watch, and you do not need to own an Apple phone to use an Apple Watch. In the figure I showed, it demonstrated that in our city, people at a higher socioeconomic status are much more likely to own an Apple phone, which means you can get an Apple watch. So, when we talk about using these otherwise widely available types of technologies, we run the risk of having an even more uneven playing field if we do not have devices that are compatible across platforms. 

Bradley Knight, MD: You talked a lot about wearable devices, but there are implantable cardiac monitors. There are also a lot of patients with an implantable pacemaker or defibrillator, particularly with an atrial lead that can detect AFib. Of those options in looking for AFib, what are the pros and cons of those different strategies? 

Rod Passman, MD: Obviously, the patients who have transvenous devices, we take advantage of that. Patients complain, though, that they're not told about their episode of AFib. We're told about their episode, and then we need to make a decision. So, it's a bit paternalistic. Implantable monitors are great, but they're expensive. They require a lot of infrastructure to receive that data. I would argue maybe we're not that interested in a 2-minute episode of AFib that occurs once a year. Again, we ultimately get that information and then we decide what we tell the patient. In this digital health era, the patient could actually detect the AFib themselves, decide what they want to do with it, and manage their AFib using these devices. 

Bradley Knight, MD: I think as an example of how little our patients really have control of their implantable device data, a patient said to me this week that they go back and forth between Chicago and Florida for 6 months of the year and that they do not want to bring their remote monitor with them. They asked me if they could get 2 monitors, and the answer is no. That remote monitor is paired with their implantable device. So, it is not easy for patients. 

Rod Passman, MD: Correct. I mean, ultimately, they all need to move to smartphone-based transponders, but there are patients who are very savvy, and in the era where we own their data and let them know when we want to let them know, I don't think that is pertinent to some patients. They want to know how much AFib they have, and what the impact is of their lifestyle changes or the drugs or treatments that we give them. 

Bradley Knight, MD: We still put in a lot of implantable loop recorders to monitor AFib. Do you think that wearables eventually will completely replace the need for that? 

Rod Passman, MD: I think it depends on the situation. For example, if you care about a single 10-minute episode in the middle of the night for someone who had a cryptogenic stroke, it's going to be tough to have a wearable that reliably picks that up. But if you really want to look at things like AFib burden or reduction in AFib over long periods of time, I think a wearable is a much more cost-effective approach. I think that you have to pair the sensitivity of the device with what you're interested in. Most of us wouldn't be interested in that single 6-minute episode of AFib. The cost and infrastructure needed to receive that data in order to adjudicate it and respond, is only usable in certain parts of this world, and this is a worldwide problem. 

Bradley Knight, MD: There are a lot of other new technologies that have been looked at, such as recognition of facial blood flow changes with photoplethysmography (PPG). Do you see any future technology that will replace the standard wearables such as phones or watches? 

Rod Passman, MD: Well, there are sensors that are already available in mattresses that can detect your heart rate, and in theory, your rhythm. Cameras and mirrors can use facial PPG to see small changes in facial coloring. The way you pronounce certain vowels when you're in AFib is different than in sinus rhythm, so when you're talking on the phone, they can sense that. They can also collect the data that comes off your chest with a smart speaker. So, you can imagine that between all those sensors in a watch, you could have 24/7 coverage for AFib if you really wanted. 

Bradley Knight, MD: Does the vowel thing work if you grew up in New York City or the Midwest? 

Rod Passman, MD: That's a great question. I think that anyone from Long Island where I'm from, it would not work. 

Bradley Knight, MD: Rod, you're also the national principal investigator for the REACT-AF trial, which is, as many people know, an over $20 million National Institutes of Health (NIH)-sponsored or funded, or at least partially funded, trial. Can you give us a status update of that trial? 

Rod Passman, MD: Sure. For those of you who don't know, this is a randomized trial comparing the current standard of care of chronic direct oral anticoagulant (DOAC) therapy with a strategy of pill-in-pocket anticoagulation using a customized algorithm on an Apple Watch. It is NIH funded. We're at about 25% enrollment, and we should be at about 50% in the next 6 months or so, if all goes as planned. We have about 85 sites in the United States, and we're now exploring some sites in Canada. So, if you're listening to this and you're a site, thank you for your contributions and keep on enrolling. We need more patients. 

Bradley Knight, MD: Do you see anything else in the future? I know there are a lot of incredibly small wearable flexible technology that are under development. Some of our colleagues at Northwestern are part of that. What do you think about these tattoo-size objects? 

Rod Passman, MD: Yes, there are amazing things. These biometric sensors are thin films that can be put on the body. I actually think that wearables make a lot of sense because you can use them over a long period of time. I kind of like my watch—I get my texts and messages. I think that in terms of compliance, by combining these biometric data points with something that is functional for other reasons, it is really your best bet. No one wants to wear something separate for this sort of purpose. I think, ultimately, there will be inexpensive PPG-based bands that use artificial intelligence that will be highly reliable and that are going to be sort of a worldwide option for people who don't want or cannot afford a more sophisticated device that also tells time. 

Bradley Knight, MD: I think in our EP world, we think of monitoring as a way to look for patients who are having recurrent AFib or patients who have already been diagnosed with it. It seems to me that there is still a huge role for screening and detecting previously undiagnosed, asymptomatic AFib. There has been a lot of debate. The current guidelines from large organizations recommend not doing that screening, which you can make the argument of “Why screen?” if it's not going to change what you do, but it clearly does. It is hard for me to quite put together why there is not a recommendation now for screening everybody for AFib, at least an electrocardiogram (ECG). 

Rod Passman, MD: That's a great question. I think to your point, we don't have amazing data on finding AFib early in those patients through mass screening. We do recommend opportunistic screening, so when a patient comes into the office, you check their pulse, and if it's irregular, you do an ECG. All the guidelines sort of support that. The question is, should we be screening the mass population? To date, we only have one large study, STROKESTOP, that showed an absolute risk reduction of about 4%, and that only looked at patients aged 75 and 76 with multiple risk factors. One study that is coming out and, full disclosure, I am part of the steering committee, is Heartline. This is a study using the Apple Watch to screen the population over age 65 and randomize to either a smartwatch or routine care. The question is not only if we can find more AFib, which the answer is clearly yes in every study we've done, but the ultimate question is, can you treat those patients and prevent stroke? I think for most of us, it makes sense. We know that in many patients, stroke is the first manifestation of the disease or heart failure is the first manifestation. I think it's now upon us to prove it. 

Bradley Knight, MD: As many of our sophisticated patients ask us, are there any questions I haven't asked yet? 

Rod Passman, MD: I would add that we are pretty fortunate that where we work in Chicago, many patients come in with these technologies. However, I do think that as an organization, we need to sort of prove that this isn't just for the worried wealth. That using digital health devices keeps people away from the emergency department, reduces hospitalization, and reduces sort of the expensive medical grade monitors that we commonly use. So, there is a lot of room for good research in this area. 

Bradley Knight, MD: Great, thank you very much. I appreciate your time. It's a great presentation and I look forward to these trials that you're involved in, particularly the REACT-AF trial. Thank you very much. 

Rod Passman, MD: Thank you.

The transcripts have been edited for clarity and length.