I’m Aware That I’m Rare: the phaware® podcast
Episode 596 - Daniel Lachant, MD
For decades, pulmonary arterial hypertension patients have waited three to six months between clinic visits hoping nothing changes. Dr. Daniel Lachant is flipping that model on its head. By turning wearable tech into real-time cardiac monitors, he’s proving that subtle heart rate shifts during a simple six-minute walk at home can reveal improvement or danger long before a traditional appointment ever could.
My name’s Dan Lachant, Associate Professor at the University of Rochester. I’m a pulmonologist by training. I work with Jim White, MD, and we have spent the last eight years investing and incorporating technology to help improve clinical research assessments in pulmonary vascular disease.
It all started when I started learning about pulmonary hypertension working with Jim White. I had never heard or seen the six-minute walk test before. Then, all of a sudden, I’m seeing patients walking back and forth in the clinic, and we see how far they walk, and we try to say, “Well, is this a good distance? Is this not a good distance? Were they trying? Were they not?”
Using some of my exercise background, I started talking to Jim White more about this. “How do we know someone’s physiologic limit? How do we know they’re just not trying?” Really get into the weeds of what went into a walk distance. So he bought an athletic Mio Alpha 2 wristwatch. We started recording continuous heart rate, more to just see what was the heart rate at the end of the six-minute walk. Not what did they do throughout the entire walk… just right when they stopped walking, what’s their heart rate?
As a part of that study, we took the whole data package. We started seeing what was their pulse rate curve, what was limiting them, how high was their heart rate before the end of the test. Really what went into them achieving a certain walk distance. In this first pilot study, we saw that patients liked the device. No one said, no, don’t put it onto me. So they were really engaged and wearing devices to help learn more about their physiology.
There’s about 25 to 30% data loss with photoplethysmography. So just using light wave technology to measure heart rate due to limitations of the device and not fitting on the arm well, pulmonary hypertension related factors, so low pulse rate pressure, so the device can’t read accurately. Because of that, we started exploring other devices. That’s when we started looking at chest-based devices, really getting at ECG, seeing what is the electrical activity of the heart during activity.
As a part of it, it also included accelerometry data. So now we could really see motion and physiology in a sensor. And in incorporating this, we said, “Well, let’s see if we can use this to monitor or detect improvement after adding therapies. Can we use this to monitor patients at home if we know what their index level is in clinic, and then we see what they do at home, how do they compare?”
That’s really where we started using devices technology. Now, we’ve gotten to the point where we’ve had over a hundred patients perform these unsupervised home six-minute walk tests wearing heart rate monitors. We’ve been able to estimate walk distances. Importantly, we’ve had no fall safety issues, complaints. Patients have been very compliant with it. They actually like the idea of having more frequent assessments to know what’s going on with them. They actually say it actually is their exercise. So some of our more limited patients, they put these devices on, they do a six-minute walk test, and they feel like they’ve done more than they had prior. Really this is just a way to gather more data points frequently so we can monitor treatment response. We can calculate risk scores more frequently, and we can really detect when drugs are starting to help patients based on timing of improvement in physiology motion.
Gossamer Bio invested in looking at this metric we call cardiac effort, so the changes in heart rate relative to a walk distance. They used it in their exploratory Phase 2 sub-study. That was very exciting because in a very small fraction of patients, we were able to detect a difference after starting seralutinib compared to placebo at week 12. So, we can get an earlier readout on improvement in physiology relative to a walk distance.
Wearable devices over the last couple of years have just exploded in terms of who makes them, where you can put them on your body. You can put it on your ear, chest, arm, hip, leg, whatever. Every company has their own proprietary algorithm. They have their own classification for what’s a step. They have their own classification for light activity, moderate activity. So, kind of comparing these different devices can become difficult just because there’s no standardization.
It does provide an easy way to see what patients are doing at home, which is great. The problem is there seems to be a disconnect with when we passively monitor patients what they can do versus what they do do. Unfortunately, more patients can probably do more than what they do, and it’s because of all the behavioral influences, the external factors. They’ve had a chronic disease that’s changed how they live their life. Even though they feel better, their activity may not reflect that because they’ve adjusted how they do certain tasks. Their behaviors have just influenced movement, which even though physiology’s improved, passively monitoring how somebody lives their life may not change with it.
That’s why we believe that doing a structured active physical assessment, such as the six-minute walk test, is a better way to see what’s going on. You can do it more frequently in the home setting as opposed to daily steps where you need 1 to 2,000 steps a day to live. The,n on top of that, it’s more what makes you move. You could have a very bad right ventricle, but do 8,000 steps in a day because you have to work two jobs to pay the bills. You could have a very compensated right ventricle doing extremely well in therapy, but there’s no reason for you to leave the house, so therefore you’re not going to leave the house.
That’s one of the pitfalls of these new devices is although they’re everywhere, they provide a lot of data. It’s just we don’t know what some of it means, or it’s hard to use as a marker of treatment response. I think there’s two ways to look at it. I think passive monitoring, so putting an Apple Watch on, putting a Fitbit, whatever device you like is a way to tell you if somebody’s getting worse. If their activity level goes down, that tells you something’s not right. By the time we’re detecting it through activity, the right ventricle vasculature’s already changed. If we’re looking for improvement, we want an active task with heart rate monitoring to show that physiology’s improved, movement’s improved, and that things are better.
I think going forward, 2026 and beyond, now that we have this technology, it makes sense to incorporate it into our routine care. When we’re starting a new therapy, having more frequent assessments at home tells us the drug’s working. Having more touches at home shows us what somebody’s actually doing as opposed to waiting the traditional three to six months gap with no information, not knowing what’s going on. I think embracing and finding ways to use these home monitoring techniques is the wave of the future. We have a data set we’re currently analyzing right now where participants did four walks throughout the year. We have quality of life assessments through Emphasis 10, and we are going to look at how they felt versus what these objective physiology, functional assessments show.
Now that devices are cheaper, more scalable, participants, patients could take them home for a longer period of time, so we could actually do more frequent quality of life and physical functional assessments at home and see how they track together. Do participants and patients who feel better one day, what does their walk look like, cardiac effort, heart rate changes, versus the next week when they’re not feeling as well. Now that technology’s at a price point where we can buy more devices or figure out a way for patients, participants to get them, we can just get more frequent assessments. Two, three years ago, we were talking thousands of dollars for these devices, so we didn’t have the ability to have them perform these tasks every week or month because we didn’t have the equipment.
As technology continues to improve, patients with high blood pressure, they buy home blood pressure monitors to do more frequent assessments. As the prices for these devices go down, and we show that we can analyze this data, or they become incorporated as outputs from these devices, this is something patients could buy on their own and track themselves. They don’t necessarily need a physician or research team to analyze, tell them what this data means; it’ll become automated in the app or whatever program they use, which will give guidance on what’s going on.
Having patients bring in home information is totally part of the treatment plan going forward. As part of these research studies and patients performing these walks at home, we’ve looked at changes in physiology and six-minute walk in between visits, and we’ve checked on patients because of abnormal heart rate responses. We’ve checked on patients to say, “Wow, your walk improved. Has the drug helped you?” These touches have definitely improved patient care. Some of them have actually incorporated into their routines where we get updates, and they just say, “You know what? My six-minute walk at home has been stable.” So, once again, it’s just another touchpoint that tells us things are going well with somebody.
Patients know that I’m very interested in exercise and that I promote exercise. We collaborated with the PHA, and we created exercise videos that we recommend for all of our patients. These same patients who know that we’re interested in wearable devices, if they have an Apple Watch, Fitbit, they know I’m interested in seeing what their daily steps are, their activity time. So during the visit, they’ll pull out their phone, and say, “Look, this is what I did.” We review in real time what their past one to three months were in terms of activity. If we see a decline, I say, “What’s going on?” If things look great, we congratulate them, and they continue on with their activity. But we do incorporate daily activity. I don’t think it’s the most sensitive measure, but it definitely provides another touchpoint just to see what they’re doing outside of the clinic.
One of the values of a home six-minute walk cardiac effort, heart rate monitoring during the six-minute walk, we’re very excited on the fact that we found that changes in the home setting on a modified six-minute walk course. So 30 feet in the home, as long as somebody uses the same walking space at home, the changes that occur in clinic are the same changes that we observed at home.
I think that’s exciting that now we have a functional assessment that tracks with in-clinic assessment. We know so much about the six-minute walk. We know so much about heart rate, peak heart rate and things like that. It allows us to feel more confident in these measurements when we evaluate for stability, improvement, or if we stumble upon worsening.
Thank you for listening. My name’s Dan Lachant, and I’m aware my patients are rare.
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