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Melanie Cole, MS (Host): Welcome to Better Edge, a Northwestern Medicine podcast for physicians. I'm Melanie Cole. And we have a panel for you today highlighting recent publications and outcomes from the chronic thromboembolic pulmonary hypertension or CTEPH team at Northwestern Medicine's Blumh Cardiovascular Institute. Joining me in this panel is Dr. Daniel Schimmel, he's an Associate Professor of Cardiology at Northwestern Medicine; and Dr. Stephen Chiu, he is an Assistant Professor of Cardiac Surgery at Northwestern Medicine.

Doctors, thank you so much for joining us today. And Dr. Schimmel, I'd like to start with you. How has the CTEPH Program at Northwestern Medicine's Blumh Cardiovascular Institute evolved in concept and practice over the past few years? Give us a little bit of an overview of this program, how the team has grown the program into one of the most advanced in the country, and what role the multidisciplinary care has played in this success.

Dr. Daniel Schimmel: Well, thank you, Melanie. I appreciate that question. This group, the CTEPH program, i've been so excited since its inception back in 2014. Acute pulmonary embolism was where a group of us had first gotten excited, you know, 10 years ago and thinking about new devices, new therapies, new protocols that could treat this patient population. But what we found treating that group was that there was a subset of people who are presenting, who had ongoing shortness of breath for years. They didn't just have one episode of acute decompensation, but they had had maybe a pulmonary embolism 20 years prior, and then maybe they're treated for asthma for a couple years and that was unsuccessful. And then, very late after being short of breath for years, were finally diagnosed with this syndrome of CTEPH, which is clot that doesn't resolve and results in elevated pressures in the lung and strain on the right side of the heart as it pumps to it. And so, when we first identified this group, I really had very little familiarity with CTEPH.

I had a good friend in pulmonology, a pulmonary hypertension specialist. And I said, you know, "What is this? I'm seeing these patients with very high pressures." And he's like, "Oh, yes. It's a very small subset of patients and we end up having to send them out to this hospital on the west coast who has been treating it independently for a long time. But we had patients who couldn't travel. And the therapies sometimes required days in the hospital or month out by that hospital, not just being admitted. And very thoughtfully, we said, you know, "I think we can offer this here at Northwestern." We have all the tools, we have the specialists here. It's a great city for people to travel to if they need it. And we could serve the Midwest or the East Coast or the nation as well, and provide an alternative choice.

And so, over the years, planning with initially Dr. Chris Malasarian, one of our surgeons, Dr. Mike Cotika, one of our pulmonologists. And then, growing the team from our initial three physicians to a very robust practice, Stephen Chiu joining us, Dr. Stephen Chiu, a very talented surgeon who trained specifically to perform this very complicated surgery, we've had great success over the past 10 years.

Melanie Cole, MS: Thank you so much for that. And Dr. Chiu, as one of a handful of centers that offer PTE and BPA, discuss the program's volume and recent volumes in both treatments. In a specialized center like this, how does volume correlate with outcomes?

Dr. Stephen Chiu: Thanks a lot, Melanie, and thanks for the invitation to join this podcast. I really appreciate the chance to talk about this disease that's near and dear to my heart. And I tremendously enjoy treating patients with this problem, because both surgery in the form of pulmonary thromboendarterectomy or PTE and interventional treatments in the form of balloon pulmonary angioplasty can offer great symptomatic and life-prolonging benefit in the right selected patients.

Of course, with time and experience, the outcomes for any procedure become better as operators become more experienced. But this has been studied a lot in their literature for both of these procedures. And we even are heading up a study that looks at the outcomes of the surgery or PTE across the country, using the National Society for Thoracic Surgeons database. We look at outcomes over the last 10 to 12 years in the country. And we see a clear volume outcome relationship for the surgery. So if a center does more than 10 or so PTEs per year, your risk of not surviving surgery is one-third of those that perform less than 10 per year. And this is regardless of whether you do a consistent low volume or not. And I think that this speaks to needing to get to the correct centers that perform a high volume of surgery. And here at Northwestern, we perform close to 40 per year pulmonary thromboendarterectomies. Last year, we landed at 38.

And then, on the BPA side or the balloon pulmonary angioplasty side, the learning curve seems to be somewhere in the volume of hundreds. And Dr. Schimmel, as our BPA operator, has done nearly 500, if not surpassed 500, in the past month or so. So, the vast experience that we've been able to gain both through visiting other centers and developing our practice here at Northwestern have allowed us to achieve great things and good outcomes for our patients.

Melanie Cole, MS: Wow, that's quite a volume. And Dr. Schimmel, when you think about the multidisciplinary model you've built and the core components that have made it successful, both clinically and in terms of outcomes, you recently published a paper on outcomes of multidisciplinary CTEPH care. Give us a little bit of an overview of the paper, its impetus and findings, and the most important takeaways from that study, how they change or reinforce how we think about treating CTEPH.

Dr. Daniel Schimmel: I think, historically, thinking about specialty care, you go to see, say, a pulmonologist because you have chronic obstructive pulmonary disease or you go see a cardiologist to treat coronary artery disease. This particular disease subset has pulled on the knowledge base and that typical testing modalities, the different specialties use on a regular basis. And because of that, the role of the cardiologist, the cardiothoracic surgeon, the pulmonologist, the radiologist, like if I asked a radiologist to look at a CT scan of a chest and tell me if the patient has CTEPH or not, there's only about a 60% accuracy to that unless you have a very specialized radiologist who knows how to read these scans, who knows how to protocol the scan so that it's done in the correct way in order to answer the question that's in front of them. And so, it takes a group of dedicated people for each of these specialties to come together on a regular basis and to have honestly administrative support from the hospital who says, you know, "We're going to provide a space and time for this group, because we see the value for the community, we see the value for the hospital. The patients are the center of that."

And so, we've been lucky enough to have a nice group of people who get along well, and not just work together well, but hang out together well. And people have come and gone from the group over the years, radiologists or hematologists, and there has been a core group of us that cardiac surgery, cardiology and pulmonology have stuck through and built. But we've always been very careful about people coming in and out that they see the vision of working together collaboratively, and the need for each other's expertise. I don't think there's any one cowboy in this group, or cowgirl. We have everybody a champion in their own space and respecting each other's space. So, I think that's really important for multidisciplinary team. And this disease is one that requires that multidisciplinary expertise.

Melanie Cole, MS: That's an important point. And Dr. Chiu, the study reported zero 30-day mortality for both PTE and BPA. In addition to that multidisciplinary care, which you've both emphasized, what factors do you think contribute most of these outcomes? How are you interpreting the implications of those outcome differences across those treatment modalities?

Dr. Stephen Chiu: I think probably what these outcomes speak to is not just the multidisciplinary care, but the immense amount of attention to detail and personal care that patients receive from every member of the team at Northwestern. So, this goes from diagnostics, going through the clinics, having interactions with the clinicians who really listen to and make sure that the diagnosis is correct and that we're verified through the multidisciplinary team meeting that the diagnosis is correct and what procedure we think they would benefit most from, and fitting that to the right patient and then taking them through the intervention, whether it be surgery or BPA, and then the immense amount of care that our support teams provide on a hour to hour and day-to-day basis in the ICUs, on the general care floor, everything from nursing staff, respiratory therapy, occupational therapy, physical therapy, social workers, making sure that the right things happen for the patients at the right time to prevent complications and mortality after procedures.

The immense layers of care that we provide at Northwestern help recognize any complications that happen early, treat them appropriately and prevent them from having devastating consequences that altogether helps provide the best outcome for patients and helps us achieve such good 30-day mortality rates.

Dr. Daniel Schimmel: If I could layer into what Stephen said, you know, in our multidisciplinary teams along with diagnosis and the group coming up with a treatment plan, I think one of the main interventional differences in this patient population is what's the comorbidity of the surgery for that particular patient, and where in location does the chronic clot sit? Is it very proximal? Is it very distal? There's certainly a transition zone where maybe someone might benefit more from balloon pulmonary angioplasty, or they might benefit more from surgical pulmonary thromboendarterectomy. And then, there's very clear differences where one patient is going to do better with one or the other.

And I guess, finally, I'd say sometimes it's a combination of both. Sometimes Dr. Chiu and I get together. And we say, "You know what? I think, Dr. Chiu, this is a great patient for you in this area. But I think at the end, I might have to do something with balloon pulmonary angioplasty to this left lower lobe, posterior basilar segment to get that segment open." Because the pulmonary artery tree has such size differentials from the main artery down to the distal vascular bed, the treatment really can't be the same.

I think Dr. Chiu's an amazing surgeon, but if he could pull a clot out of a two-millimeter vessel, he actually probably could, but, you know, very far away, it's amazing when he does. And similarly, I'm going to have a lot of difficulty trying to open up a vessel that's greater than six millimeters in diameter. It's just hard to displace that much chronic clot. And so, there are patients who are going to benefit more from what Dr. Chiu has to offer. There are patients who might benefit more from balloon pulmonary angioplasty, and patients who might benefit from both. And then, underlying all that is a real reliance on the medical therapies, whether that be the ones that are mandatory to prevent recurrence of clot and those that improve cardiac output and drive down pressures and maintaining those things.

So, you know, it's not just one therapy, you're cured and you're done. These patients have a risk of recurrence and they have to be educated in how to prevent it. And they have to understand the whole treatment plan. It's a commitment on the providers and the patient.

Dr. Stephen Chiu: Yeah, I think that's absolutely right. And when this disease was first discovered, it was surgery or nothing. And patients basically were at the end stages of disease. But as disease awareness has grown, patients start to get to us earlier in the disease process, with milder and milder pulmonary hypertension, but still significant lifestyle and activity limitations.

it's nice to have the whole spectrum of therapies available for the sickest of the sick and those who are relatively well that would've been previously considered too well to undergo an intervention, but actually nowadays might be eligible for them. With the improved safety profiles, techniques and hospital care, we can take care of the full spectrum of patients.

Dr. Daniel Schimmel: One of the tough things that Dr. Chiu mentioned there is the improved techniques. In 2016, I made my first trip with Dr. Malasarian out to San Diego to watch one of the premier surgeons who did this procedure and learn from them. And then, we didn't just go out once and observe and come back and try and test it. We've had a commitment to training ongoing. I went to Japan for another week to train with their premier operator who did balloon pulmonary angioplasty. A couple years later, Dr. Malasarian and I went to Germany, and then, I went on to Paris. And in each institution, there is some variability. We had the opportunity to take what we saw as the successes and bring them back. Dr. Chiu can talk about his specialized training experience, which is separate. And now, we have people traveling to Northwestern to come and observe us, which is the full cycle that you hope to attain, I think, is to learn and then share your experience.

Dr. Stephen Chiu: So, I'm in my third year of practice here. But I think every step along the way is what's been consistent, is that we've sought out world expertise to build our program. And part of that effort, I did do a one-year specialized fellowship in pulmonary thromboendarterectomy at the National Reference Center for PTE in the United Kingdom. And so, the one-year experience there gave me exposure to every phase of care for patients going through PTE, all the way from preoperative selection, diagnosis, operative planning, doing the operation, taking care of the patients, and following them up three, six months, one-year later.

It was truly a special experience to learn from a group of very talented and dedicated surgeons who had built the program from decades prior and we're now performing upwards of 200 surgeries per year. I really credit those surgeons in giving me the expertise that I brought back to Northwestern and feel privileged to be able to provide that to the patients of Chicago, the Midwest, as we expand around the country.

Melanie Cole, MS: This is such an engaging conversation and a comprehensive, multidisciplinary approach as you both have mentioned. And Dr. Schimmel, In your recent review on BPA complication management, and we've talked a little bit about patient selection, you emphasize prevention and preparation. Speak about some strategies that other clinicians can implement to reduce risk and manage those complications and how access to the resources and the expertise as we've been discussing here, which is so important at a comprehensive CTEPH Center, support those efforts.

Dr. Daniel Schimmel: Yeah. I think to get to that, you have to understand a little bit about how research is published, how it's accepted, what the audience is. There's a lot of excitement, I think, to get into treating CTEPH both surgically and through minimally invasive ways. Balloon pulmonary angioplasty seems so very accessible, because there are cath labs everywhere or interventional cardiologists who know how to do angioplasty and have been doing stents for years. And when you say, "Well, I can use a balloon in an artery and expand that," you know, I can do that.

I think the tough part is when you don't have that multidisciplinary team to help you select the correct patients, or you don't have your own high volume experience to select the right patients. You could get yourself into a little bit of trouble with complications. And you could say, "Well, there are some people they use this term, that's the cost of doing business. I'm trying to help somebody," and I don't accept that kind of mentality.

I think that you commit to treating a particular disease, you train for it. And this most recent paper on complications, sometimes people don't want to publish a paper like that where they say complications happen. They want to talk about the rosy aspects and the complications are kind of this thing at the end of a paper where we say, "Look, the complications were low." This paper is really giving you a recipe for how to avoid getting yourself into a situation. But if you did get yourself into a situation, how do you get yourself out? So, it's very methodical. It gives you very nuts and bolts conversation.

And I think when you have a long time experience and a high volume-- we've been, like I said, doing these procedures since 2016, around 500 of these procedures over that time with increasing volumes every year. We felt like our complication rate is very low, extremely low, which is wonderful. And that's patient selection. And then, when you look at the complications, they tend to be very mild. There's mild and severe complications. We have not had severe complications from BPA. And I would love to say, "Oh, that's great. It's me." But you know what? It's the people who trained me and the people who showed me how they did certain things. And so, I have a lot of gratitude for the people who invited me into their cath lab to help train me and provide the best outcome possible.

Melanie Cole, MS: I'd love to give you each a chance for a final thought here. And Dr. Chiu, beyond the recently published outcomes data, what ongoing research product projects within the Blumh CTEPH team are you most excited about? Looking ahead five years or so, how do you hope those outcomes for people living with this will have changed as a direct result of the work that you're doing at Northwestern?

Dr. Stephen Chiu: I think in a rare disease space, anytime we develop a clinical center of expertise, it's almost our obligation to do studies for patients so that the disease is better recognized, it's more appropriately treated, and then we develop new treatment options or approaches.

We have studies going in all phases. We have studies of acute pulmonary embolism and risk factors for developing CTEPH. We have studies on AI-driven recognition of CTEPH going on and how that can help feed into what we call a post-clot clinic for early detection and early recognition of the disease so that patients are not at the end-stage of their disease before they present.

And then, we have basic and translational science studies ongoing in my lab, in the labs of our pulmonologists that look at identifying novel disease mechanisms and how we might be able to identify new targets for prevention treatment or prevention of complications in the postoperative period, or disease recurrence in the long-term.

Melanie Cole, MS: Well, that's very exciting work, Dr. Chiu. Thank you for telling us about that. And Dr. Schimmel, last word to you, based on these findings, how do you see comprehensive CTEPH programs evolving in the US? What should patients are referring physicians know about when and where to seek that specialized care? And for fellow clinicians listening, if you could think about one practice insight, mindset that we've been discussing here today from your work that you would encourage them to take back to their own institutions.

Dr. Daniel Schimmel: I think the most important thing when I think about providers in the community and other academic centers is recognition of patients after acute pulmonary embolism who don't have return to good respiratory function. You know, three or six months after the pulmonary embolism, they've been on anticoagulation, but they're still short of breath. And maybe their echocardiogram looks okay, but they're still short of breath, or maybe their echocardiogram does not look okay. If that six-month mark, if that patient has not returned to normal, then they should be considered for referral to a CTEPH center. And I know that's like, "Well, I can do that follow-up testing," and there is definitely testing available to everyone.

But the testing, the outcome of that, the identification of it, it's kind of insidious sometimes. The V/Q scans, which is our diagnostic test of choice to identify a vascular limitation from chronic clot, technology's been around for a long time, but very difficult to interpret. And so, unless you have a really laser pointed focus on identifying it, you could easily miss the diagnosis of CTEPH. And sometimes we use CPET studies. I know that sounds very similar to CTEPH, but cardiopulmonary exercise testing to identify the exercise limitation that's specific to an unresolved pulmonary embolism. And those are difficult tests to interpret as well. So if I had a patient six months after their PE and they're still short of breath, if all the post-testing looks totally normal, that's one thing. But if it's not perfectly normal or they're still short of breath with no other competing cause, I would strongly recommend referral to a program that specializes in CTEPH because it's one of the few things that causes shortness of breath or pulmonary hypertension that is treatable back to a normal pressure and normal functional status. So, that is the one big takeaway that I'd recommend for any physician listening, taking care of patients who have had a PE in their past.

Melanie Cole, MS: Thank you both so much for joining us today and really sharing your incredible expertise for other providers and to refer your patient or for more information. Please visit our website at breakthroughsforphysicians.nm.org/cardiovascular to get connected with one of our providers. That concludes this episode of Better Edge, a Northwestern Medicine Podcast for physicians. I'm Melanie Cole.