BackTable / VI / Podcast / Transcript #120

Podcast Transcript: Pulmonary Embolization Interventions & Response Teams

with Dr. Eric Secemsky

Interventional Radiologist Sabeen Dhand talks with Interventional Cardiologist Eric Secemsky about building a Pulmonary Embolism (PE) Response Team, and about the various techniques for treatment of PE used in his practice. You can read the full transcript below and listen to this episode here on BackTable.com.

(1) Classification of Pulmonary Embolisms: AHA Criteria and PESI Score

(2) Right Ventricle Imaging: Echocardiogram vs. CT

(3) Developing a Pulmonary Embolism Response Team

(4) Communication Within a Pulmonary Embolism Response Team

(5) Timing of Pulmonary Embolism Interventions

(6) Systemic Therapies: Thrombolytics and Anticoagulants

(7) Interventional Therapies: Catheter Directed Thrombolysis vs. Thrombectomy

(8) Catheter Directed Thrombolysis: Sedation, Imaging, and Devices

(9) Future Implications for Surgical Embolectomy

(10) Recommended Literature and General Advice for Pulmonary Embolism Interventions

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[Dr. Sabeen Dhand]
Hello, everyone and welcome to the BackTable podcast, your source for all things endovascular. You can find all previous episodes of our podcast on iTunes, Spotify, and on BackTable.com.

This is Sabeen Dhand as your host this week and I'm really excited to introduce our guest today, interventional cardiologist and a great friend of mine from school, Dr. Eric Secemsky, coming to us from Harvard. Welcome, Eric.

[Dr. Eric Secemsky]
Thanks, Sabeen. I appreciate the invitation to be here today, my good friend.

[Dr. Sabeen Dhand]
We're happy to have you, man. I want to know for myself and for our listeners, how did you come from being a friend with an average guy like me to now being this BMOC? I mean big deal, research giant, just an outstanding leader in your field today.

[Dr. Eric Secemsky]
I would say we were more acquaintances than friends... No, I'm just kidding. You've always been a good friend of mine. For the listeners, Sabeen and I were medical students together and good friends throughout medical school.

It's been an interesting past four or five years in particular, because I didn't really know I was going to go into the peripheral vascular space. I was always interested in interventional cardiology. I kind of got interested during my fellowship, primarily from one of my mentors, Ken Rosenfield, over at Mass General. I ended up staying on for some extra training in the peripheral vascular space and that really has become the primary focus of my career. I was fortunate to get recruited over to Beth Israel to kind of restart the endovascular interventional program and then I continued my research in the endovascular space. But, if you had asked me five to seven years ago if this is what I'd be doing, I could even answer that question with any certainty of where I am right now. So, it has been a great run and I appreciate the kind intro.

No matter where I go, high or low on the totem pole, you're still going to be my friend, so don't worry.

(1) Classification of Pulmonary Embolisms: AHA Criteria and PESI Score

[Dr. Sabeen Dhand]
We all knew you'd make it big, Eric. We all knew that. So we're going to be talking about PE intervention. We've talked about PE intervention in the past on BackTable and we've kind of focused on large-bore thrombectomy, but I wanted to go back. I mean, PE intervention has been around for a while now with other devices, and I really want to know how your practice approaches it. Just to start off, how do you classify patients with PE?

[Dr. Eric Secemsky]
Well, just a little bit of context of how I got into this clinically, and as well on the research side. You know, I was back in my training at Mass General when Ken Rosenfield and some other multidisciplinary specialists at Mass General decided that we should have a multidisciplinary program for the management of PE, which became the PE response team or the PERT team, and I'll talk about that in a little bit. So, that was kicking off when I was finishing my general cardiology fellowship and the downward flow of work was that I was in charge of doing the off-hour echos for people in the Emergency Room with PEs to help stratify. But, the exposure to PE was really helpful as that became a part of my career, because I've seen all flavors of PE and, really, the treatment's changed dramatically over the last eight years.

With that context in mind, I think one thing that we still are getting our heads around is how to classify PE. I think we've kind of got a good criteria in terms of classifying massive, submassive, and non-submassive (some people call it low risk)... But really understanding, particularly within that submassive group, what is high risk? In the AHA criteria right now, it is poorly defined. We look at submassive, which means that you have any evidence of RV dysfunction on CT scan or echo, or any signs of RV necrosis with biomarkers of BMP or cardiac enzyme troponin are elevated.

But, the European guidelines go a little step further. They first say, “Let's look at your PESI or your simplified PESI score.” So, let's put your clinical context at the front of that decision and then, from there, if you have both a high PESI score or a high sPESI score and then RV dysfunction and biomarkers, you fall into the intermediate high risk. Or, if you have either dilation or biomarkers that are positive, then you are in the intermediate low risk group.

So, they are a little bit more refined in terms of how they classify these patients. Empirically, when our PE phone calls, what we're looking for is, do they have any type of vital sign abnormalities? You know, it's a little bit more subjective, but what's their heart rate, how much oxygen are they on, can they complete full sentences, how stable is their blood pressure? Then, we're really looking to see what's the evidence of RV dysfunction. Usually, if it's overnight, we get a CT scan and, if it's during the day, we'll get an echocardiogram. Then, are both biomarkers elevated? And we'll get lactate also. We could talk about some refinements, but those are the heart of the patients that we're managing in the hospital.

And you know there's a massive group as well, which is the smaller nugget of the PE patients, but that's where the clinical side is.

[Dr. Sabeen Dhand]
That's good. I'm glad you kind of got into the questions that you ask because, you start reading the European guidelines and you're going “intermediate high risk?” A lot of information overload, I think.
It’s important to look at the real clinical picture. Can the patient finish a sentence? That’s a huge source of information. How much are they struggling? The clinical picture is what really wins in this.

[Dr. Eric Secemsky]
Yeah. The best part of this was, when we first started, we got those PE calls and everything was about how much clot there was. Saddle PE, clot in all the lungs. Then you'd say, "Okay, well how is the patient?" And they're like, "Oh, they're on room air, heart rate's 70s, blood pressure's normal." We'd say, wow, it's pretty amazing that they're tolerating all this clot burden but, on the other hand, it's hard to push yourself to get excited about intervention with some risk, maybe not a ton of risk, but some risk in a patient like that.

So, you're totally right. Our phone calls are really brief about the clot burden, really brief about if it is more binaries or RV dysfunction or not. Then, it's about the patient, how the patient is doing, and again with that interview. You know that with a patient who can't finish a sentence, is on a non-rebreather, that you're going to have to escalate therapy. On the other side, there's the stable patient who didn't know they even had a PE and it is easier to make that decision.

[Dr. Sabeen Dhand]
I have been amazed that we see more of these PEs now that we're focused on them. Before, when PE intervention was a thing, we'd see these PEs and report it and I didn't see the clinical picture. Now that I'm involved, I'd look at the CT scan and be like "Oh, damn, this guy's going to look really bad." And you go in and they're great and they're like "Okay, well, I came in because I just felt a little off." You know?
Clot burden is not the key but it is all the physiologic effects of what that causes.

The cardiac enzymes used are basically what? BNP and troponins? Anything else?

[Dr. Eric Secemsky]
The main ones are BNP and troponin. We are starting to get into the weeds of the PERT Consortium Database, looking at how people manage PE across the nation, and it's infrequent that centers order both of those. BNP is a little bit more common than troponin, also. Troponin falls a little bit more on the cardiac coronary side often and so it's not always ordered. But we look at both of those. In my head, what I've seen patterns of is that when the BNP, which is just a stretch of the myocardium, is elevated, but not the troponin, you have to start thinking more about a subacute PE. Now, again, this is empiric, I don't want anybody to think this is fact. But, that has kind of been my observation. Normally, when I see the troponin elevated, usually it's a more acute PE, a little bit more severe early onset RV dysfunction. When they're both elevated, you know they are a particularly higher risk acute PE patient.

Outside of that, we've been making a push to get lactates as well, and I think that's really helpful to start triaging and risk stratifying the right patient for a more aggressive upfront approach. When the lactate is elevated, we know then any hypoperfusion to these organs is a sign that we might need to really do something to relieve the pressure on the RV. We've been looking to get lactates in addition to the troponin and BMP. Those are the big three. The nice part is that the ER is so used to ordering those. So, if you remember when we were in the Emergency Room, they have kind of their-

[Dr. Sabeen Dhand]
Yeah.

[Dr. Eric Secemsky]
Yeah, and so those come back pretty quickly and you can really make some good decisions with that data.

(2) Right Ventricle Imaging: Echocardiogram vs. CT

[Dr. Sabeen Dhand]
So echo versus CT to evaluate for RV, how often do you find a discrepancy of echo being more accurate than CT?

[Dr. Eric Secemsky]
Yeah, that's a great point also. We usually get both. We are a little bit spoiled because our cardiology fellows are there 24/7 and so they carry around these small scanners to look at the function of the heart or they'll bring the big machine down. So, we usually get both. It is a limited view. It is usually an early career fellow or a first year fellow, so I am not going to hate on them, but they do their best. We use both.

Recently, we did a paper that was in vascular medicine, looking at presentation and treatment differences between men and women with PE. We found that women more often tended to have a little bit more CT abnormalities for RV function than for echocardiograms. This was a large data set, so I don't have the granularity to tell you if the study was of the highest quality for the echocardiogram. There is a little bit of a technician-dependent approach for echocardiograms. It's not always the easiest to open up the RV and it's often that you will get a short view of it and it will make it look worse than it is. When it looks really bad, that is really easy. Obviously, the habitus part for women might have driven that a little bit. Once I see it on a CT scan and it is really over the ratio of one to the LV, I feel pretty confident that I know there is dysfunction. The echocardiogram can give you more specific data, but I can't say that I act on anything more. We will report things like TAPSE and whatnot, but probably the most helpful thing is to have an echocardiogram once they are nearing discharge to know what to surveil when you're in follow-up because it is much easier to get an echo for someone and look at RVSP and pulmonary hypertension than having to send them back to a scanner and look at the ratio again just to get an RV/LV ratio. You wouldn't want to do that very often. So, I like that for follow-up.

[Dr. Sabeen Dhand]
Ultrasound is always operator-dependent, so you always have to use that kind of variable with any ultrasound.

(3) Developing a Pulmonary Embolism Response Team

[Dr. Sabeen Dhand]
You mentioned PERT. I mean, you were part of the developing team of PERT at your hospital. Can you just go into how a PE response team functions at your hospital?

[Dr. Eric Secemsky]
Before I got to Mass General for my fellowship, I was at UCSF and it was interesting because we had no advanced therapies available. A PE came in and we anticoagulated them and, occasionally, you would get one that was incredibly sick or had a lot of clot burden and we would actually ambulance them. You couldn’t even fly them down to San Diego. They had a big thromboembolic program there and they'd either get a surgical embolectomy or some other advanced treatment.

So, now, it's 2021 and most hospitals can manage all flavors of PE now. When this was starting at our hospital at Mass General, I was a little bit on the cursory. Like I said, I was primarily manning the echo probe. But, Ken Rosenfield, Rick Channick, Rachel Rosovsky, Chris Kabrhel, really a multidisciplinary group of people, came together and said no one is owning this condition, yet it's incredibly morbid and fatal. These patients come to the hospital and no one knows what is the right decision. At the same time, more and more therapies are becoming available. So, why don't we approach this in a multidisciplinary way to make our best clinically-informed decisions, with whatever evidence is available, to help manage these patients?

You know I think it really was a unique approach. I think, if we had started the field of coronary intervention with the cardiac surgeons as partners, we would be in a better place. We're not in a bad place right now. Maybe in peripheral vascular disease, if we had started this in collaboration with vascular surgeons and interventional radiologists, all of us managing patients together and making treatment decisions together, we would all work together a little bit better. So, I think it was really special to start it in a multidisciplinary way, because these were treated by all disciplines. Interventional radiology takes care of a lot of these. Hematology, pulmonary, eventually cardiac surgery and then cardiology. It was a special time for a new paradigm for treating a disease that's been around.

(4) Communication Within a Pulmonary Embolism Response Team

[Dr. Sabeen Dhand]
Right now in medicine, what other official team do you really have that includes all these specialties? I mean, it's well known that everyone works together here. Let’s say, in your hospital, a patient comes in with this intermediate high-risk PE, they are unable to complete sentences, they are on a non-rebreather. They come into the ER. Who gets called and how does that function work? Is it just somewhat based on the day? How does the PERT team work at your institution?

[Dr. Eric Secemsky]
Moving on from that experience at Mass General, they promoted this PERT team and it became a national paradigm for treating PE and the PERT Consortium was made. Right when this was all launching, my current partner over at Beth Israel, Brett Carroll, who was only a fellow, said we should have a PE team here. So, as a fellow, as he was doing his vascular medicine training, he developed a PE team that he ran pretty much solo for over a year. He was actually a few years behind me in training at Mass General before he went across town, so we knew each other well and we were kind of coming on at Beth Israel at the same time. So, I came over in 2018 and we kind of blew it up together. He really had a mature system. I was there to help with the interventional stuff and to support the program.

Of course we had to change the name of it at Beth Israel, so we call it the MASCOT team, but it's a PE team. We have a specific pager for any pulmonary embolism. Almost like the ST Elevation MI (STEMI) pager that we have for coronary. If a sick patient comes into the Emergency Room, they page the PE pager, and that goes to our 24/7 wonderful on-call cardiology fellow. Then we always have a vascular medicine attending overseeing that fellow, usually not in the hospital, but on-call. Brett takes the majority of that, or I take that call. Another one of our partners, Alec Schmaier, will as well. So, they'll initiate kind of the first line of consult where that patient is at intermediate high risk in the Emergency Room. The fellow will be down there, get the information, get the CT scan pulled up and sent out to the group, get an echocardiogram if they can, and get some of that lab work.
Then, they'll have an initial discussion with the vascular medicine attending who is on call, whether it is Brett Carroll, myself, or our other partner. Then, usually, when there is any concern or question about whether we need to advance therapy outside of anticoagulation, so pretty much any intermediate high risk, we will have a phone call. So, we have a text-based, HIPAA-compliant app that goes out to a group of about 20 people and these are pulmonologists, hematologists, cardiologists, interventional cardiologists, our cardiac surgeon, vascular medicine, and critical care. So, a really diverse group. It doesn't matter what time of day.

Last night, it was 9 p.m. and we had a PE call. I texted him and said, "Thanks, man" because it was Friday night and I was supposed to be off. But, on the app, we will be able to look at and to share HIPAA compliant pictures of the echocardiogram, we will get the MRN through an email to look up the CT scan, and then we will have a conversation. The fellow will lead that conversation and say "Here's the clinical data, here's my exam, here's the imaging, and the lab results, and this is my empiric thought and what I think we should do." And we go around the horn and everybody gives their opinion.

[Dr. Sabeen Dhand]
That's great.

[Dr. Eric Secemsky]
Yeah. It's usually about a 15 minute phone call and we do about, on a busy week, I'd say about three or four, maybe five a week at most. We try to reserve them for ones really where we need to make a clinical decision such as escalating to an advanced therapy. I think everybody feels like they share the responsibility of the patient and the decision. When we make a decision, especially for us on the vascular medicine side, a lot of the notes and everything come in our name. We feel like we're representing the group and an informed decision that we feel comfortable with.

[Dr. Sabeen Dhand]
It's neat that you incorporate technology because that ability to share information with everyone at the same time really, really increases your efficiency. In stroke intervention, there's a couple of apps we use, even some that include AI to detect stroke and notifies everyone on the different teams. Is there anything like that being developed in PE? Is this a PE-specific platform or are you using a normal HIPAA compliant platform and tailoring it to your use?

[Dr. Eric Secemsky]
This is nothing fancy. This is just a HIPAA-compliant platform. The nice thing is that we have a homegrown OMR, which usually is bad in most roles. I've gone through several iterations and UCSF had a homegrown one, partners at Mass General had homegrown one, and everybody moved to Epic, but Beth Israel has been the hold out. But, it's web-based, so you can pretty much pull up everything and the image wherever you are, even on your phone. Yeah, so that is really the sweet spot for this OMR. We've been alright with that and usually we're all really close, even across specialties, so we text each other if we need.

[Dr. Sabeen Dhand]
That's great. It's great that you have communication between all the teams, because there's a lot of people and if you're calling each one separately, that takes a lot of time and it's an obstacle, versus using technology to your advantage.

[Dr. Eric Secemsky]
Absolutely.

(5) Timing of Pulmonary Embolism Interventions

[Dr. Sabeen Dhand]
You know, say you had a patient come in at 9 pm. An age-old question that a lot of people have is how emergent is a PE intervention? I mean, sure, a 3 pm PE case, that's easy to triage, 10 a.m. is even easier, but what happens at 11 pm? You know, patient's in the ER, how and when do you treat that patient?

[Dr. Eric Secemsky]
That moved a lot also. I think there's a couple of considerations there. There is still a lot of variability in terms of who people are bringing for advanced therapy. We're pretty conservative in Boston and as the program itself, and we'll talk a little bit about the data I think later on, but we're taking those people who really are teetering on escalation of care, so needing intubation, and potentially needing a pressor in extremis. We're not going to sit on those and we'll take them to the lab.

Jeff Weinstein, our interventional radiologist who is incredibly involved. He is a fantastic guy and a fantastic clinician. To your comment earlier Sabeen, it is so nice to see our radiologist colleagues come and round and have these amazing clinical insights that you're not used to getting from the radiology side because usually, like you said earlier, it’s looking at the scan and imagining what that picture looks like. Jeff is one of those guys who is at the bedside. I worry about him because I feel like he's in the hospital and never not in the hospital. We switch off days on who does those procedures, but Jeff will take anybody at any time and we try to do that same thing.

Now, if you look at the trials, like the early east coast trials, there wasn't a need to take them immediately and there is a whole variation in terms of how sick they were. So, there are times where, even when I was in training, when it is 2 am and we say we will do it at 8 am when the lab opens, and the patient is doing all right so we can let them wait a little bit.

I think as we, especially with the clot extraction devices for the sicker patients, know that probably getting to the lab sooner with those devices gives us a little bit better outcome. Once a thrombus becomes a little bit more organized, it is a little harder to get it all out in a single sweep. So, we have been really trying to move.

The other thing that we can chat about at some point, about massive PE, is that paradigm shift changes also where we are not only sending them to surgery or full dose lysing in the Emergency Room. We're treating those at our institution like a heart attack or a STEMI, where we're trying to get the lab activated within 30 minutes because, not only do we have these clot extraction tools, we also have new percutaneous mechanical support devices for people who are in shock to support the right ventricle. So, we have been doing more of those. We have kind of created a pathway where we can get them up, treat them like a real shock patient. Use the devices that we need to get them stable and then watch them.

[Dr. Sabeen Dhand]
Yeah, that's awesome. I do think that's almost a topic on its own that we should talk about at some point, because people classify massive as like, "Okay, those patients are dead or need surgery." But with all of your new percutaneous devices and how technology has gone on, I mean we can treat those patients and save them.

[Dr. Eric Secemsky]
Yeah.

(6) Systemic Therapies: Thrombolytics and Anticoagulants

[Dr. Sabeen Dhand]
Let's talk about, what kind of systemic therapies are your patients getting other than anticoagulation? Are your patients getting tPA or are you holding off on that tPA and taking them to the lab?

[Dr. Eric Secemsky]
The majority of our lytics go to our massive PEs who are unstable in the emergency room and we don't think we could either get them on ECMO or to the lab, and we will lyse them. Someone who arrested with either a documented PE or high suspicion for PE, we'll lyse. There is some data on half-dose systemic lysis in some massive PE. Occasionally, we've had some situations where they are not technically massive but particularly sick or have other comorbidities, where we don't think mobilizing them or bringing them to an interventional suite makes sense, and we will give them half-dose lytics. It's few and far between now.

Most of the time, everything that we do is decided in the lab. We will bring them to the lab where the only systemic therapy that we really do is obviously heparin when they come in. We used to keep people on systemic heparin and then transition them to Lovenox. Once there was no plan to go for aggressive invasive therapy. We haven't found that-

[Dr. Sabeen Dhand]
Lovenox, no oral anticoagulation?

[Dr. Eric Secemsky]
We move to oral anticoagulation. The goal that we are trying to do now is... Heparin is unpredictable. It depends on how attentive the nurses are, there's always some patient care considerations that predict whether they are going to get a high dose or low dose or whatnot. So Lovenox is probably really the right systemic agent for everyone that comes in. You know you get really good therapeutic anticoagulation that is weight-based. You can check a quick factor Xa level to make sure you are there. But you don't have to worry about some of those other considerations because the most important thing for any PE patient is that they are systemically anticoagulated, and that is better than any device or treatment you are going to do, especially for submassive.

So we are realizing now that we are not really having a lot of procedural issues on Lovenox. We could take them to do EKOS on Lovenox already in their system and that's what we were trying to avoid before. So, we are really trying to move people on the systemic anticoagulation right away with Lovenox and then a quick transition to a NOAC or DOAC, however you like to term it, as soon as the decision to not intervene further is made. If we are going to do EKOS, we don't really want them on a DOAC, but once we are done with any planned procedure, we do that as quickly as possible, as well.

(7) Interventional Therapies: Catheter Directed Thrombolysis vs. Thrombectomy

[Dr. Sabeen Dhand]
That makes a lot of sense. In your practice, how many people, of the ones that go for intervention, how many are going for catheter-directed lysis versus this newer thrombectomy at this current date?

[Dr. Eric Secemsky]
When I think about PE, I step back. They say there are 600 thousand to a million PEs a year. About 55% of them are not going to be massive or submassive. So you are looking at chopping that in half. About 45% are going to be the ones that we are going to see hospitalized. 5% of those are going to be massive and they are going to need something. So, either surgery or systemic lysis for intervention. Then you are stuck with this other chunk of 40% [for submassive]. If you take those 40 out of 100 people, I think probably about 5%-10% are going to get aggressive therapy at our institution. When you get to a good system anticoagulation, they are going to do well from the hospitalization standpoint.

This is where we need more data. Because advanced therapies have shown, and particularly in clinical practice but also trials, that we can make people feel better, but also stabilize them hemodynamically or from an oxygenation standpoint much quicker than systemic anticoagulation therapy alone. What we haven't proven is what happens after the hospitalization. That's really where the money is at.

If we have the data to say that, up front, clot debulking is going to predict, in six months, that you are going to be a more functional person with less dyspnea, then I think we would be very, very aggressive upfront. We don't have that data. The data that we have is six month follow-up data or long term follow-up data from PEITHO, which was tPA versus anticoagulation for submassive PE. People who got full-dose tPA looked the same as anticoagulants at six months and beyond. They had the same echo characteristics and, again, it was not a full cohort who had follow-up out to that far. There were some deficiencies in that study but, the bottom line of it was, getting upfront clot debulking or systemic lytics didn't predict that you were going to function better long-term. So, that is where we are still lost.

[Dr. Sabeen Dhand]
It's hard, though. I mean, it is a whole different game when you are taking out the clot. I mean, you're taking out a physiologic part versus systemically breaking it up. Do you know of any data coming up that will help answer that question for us?

[Dr. Eric Secemsky]
Great point. Granted, even when we remove proximal clot with some of these extraction devices, there is still often some distal clot that we leave behind. But a lot of these studies are what we consider more historical now and a lot has changed in that time. So, that may very well change. Again, EKOS and/or mechanical thrombectomy might improve these longer term outcomes. We don't have that data yet.

Probably the best, the most public data, is HI-PEITHO, which is a Boston Sci-sponsored with the PERT Consortium randomized trial. I think it is an international trial. I think that is going to be 60 sites. They are going to randomize people with intermediate high risk PEs to EKOS versus systemic anticoagulation. I think the primary endpoint, 7 days post-discharge, is death, deterioration, re-escalation of care, and repeat VT or pulmonary embolus. They're going to have long-term data as well. So that's probably going to be the best randomized data we're going to have and hopefully we will get a little idea and a more contemporary picture of, when you do an upfront procedure like EKOS, what do the short term and the long term sequelae look like?

From the clot extraction and the mechanical thrombectomy side, I don't know of any prospective randomized trial data that are currently public. They are still new and the hard part is that the criteria for how these devices were brought into the market.... We kind of shot ourselves in the foot a little bit to get all the data that we really wanted. Because most trials, as you guys know now, are single-arm trials and the primary endpoint is reduction in the RV/LV ratio within 48 hours.

Historically, there is data that said an RV/LV ratio greater than 0.9 or greater than 1 predicted 30-day mortality, so let's not worry about 30-day mortality, let's just look at the RV/LV ratio on the CT scan. In reality, we should have been focusing a little bit more on a hard clinical endpoint, because we don't check follow up RV/LV ratios on CT scan. Some of that data was 30 years ago in a small patient cohort that was not very diverse, so it's hard to really hang your hat on that.

The FDA has kind of given all these PE devices this faster pathway onto approval, and that has created some issues with us having all the data we need. On the other hand, also, the investment to generate that data from the company side. It's harder to justify because you can say we are in the market where people are getting good anecdotal results and that's enough for us.

[Dr. Sabeen Dhand]
Totally. Speaking of EKOS, is your practice for PE intervention mostly doing lysis right now?

[Dr. Eric Secemsky]
Yes, when we take those 40 out of 100 that have submassive PE, we end up taking maybe 5-10 of the intermediate high-risk cases. We have a discussion, and this has changed over the last year. We are a little bit newer in our mechanical thrombectomy experience. We were doing more EKOS to start, and we have kind of now gotten into the thrombectomy part of our practice. So, we have a discussion. We like mechanical thrombectomy for a couple of reasons. We like the fact that we get a pretty quick clinical improvement and also we can limit the time in the ICU, which has been really nice, especially with COVID when we worried about our ICU beds. We can get them out of the lab and either a brief stay in the ICU instead of sitting there with catheters, or straight to the floor.

From a technical standpoint, what I'm looking for and what we talked about is, obviously, proximal clot. So, if we see a lot of proximal clot, saddle embolus, any PE that's got thrombus, we tend to favor a mechanical thrombectomy. On the other hand, where you see a little more distal clot bilaterally and a not as much central clot, we'll move a little bit more towards the EKOS catheter for those. Also, if we think that there is more subacute thrombus, we've kind of anecdotally felt that the clot retrieval devices haven't been as easy to function when there is a mixed thrombus and so we will tend to use EKOS in that situation as well, although some companies will tell you that they work just as well or better than EKOS for subacute thrombus.

[Dr. Sabeen Dhand]
Of course.

[Dr. Eric Secemsky]
Yeah. So we are equal opportunists. We do a little bit of both and we do it on a case-by-case basis.

(8) Catheter Directed Thrombolysis: Sedation, Imaging, and Devices

[Dr. Sabeen Dhand]
For our listeners, I kind of want to briefly talk about your catheter-directed technique, when you're going in there. Now in most of these cases, are you using local or conscious sedation or are you going with anesthesia?

[Dr. Eric Secemsky]
In the cath lab for us, everything that we do is usually under conscious sedation. So most people get our usual protocol of some fentanyl or Versed. We don't take many people unless they are intubator-ready and under GA. We do access mainly from the groin still, but a lot of people have done things differently which I'm all for. I think the groin access is just a little bit straightforward and easier and, especially when people aren't intubated, they don't love putting large catheters in their neck. People have shown that you can do EKOS from brachial arm veins and the antecubital fossa, which is great. EKOS from the neck isn't that hard either. Putting the Inari device from the IJ works, but again it is large, especially if you go with the 24 Fr sheath... it is not very comfortable, unless... When they are intubated, we've done that. We've had some pretty good success just from doing that from the groin. That tends to be tolerable to patients. So, usually we are using femoral venous access.

Everything I do is under ultrasound, the coronary and the peripheral space, anything. So I do everything with femoral ultrasound access and we usually will do some kind of pre-close with the Perclose or mattress sutures up front if it is going to be the large bore access like for the Inari device. For EKOS, you know we just pull and hold so that is easy.

[Dr. Sabeen Dhand]
Do you do pulmonary angio? Do you worry about increasing pressures or, if you do, then what rate do you use to get decent pictures?

[Dr. Eric Secemsky]
Yeah, we'll do pulmonary angios. I don't really worry too much about the angiogram causing any issue with the clot. I haven't seen it cause harm anecdotally, in my personal experience, or in published literature. I don't do them up front if the patient came straight from the scanner and I already kind of have an idea of where things lie. Sometimes, if we are doing the Inari device or clot extraction, we'll take some puffs through the catheter (the large bore sheath).

But also recently, we had a case where it was suspected PE, but they were too unstable to go to the scanner. They weren't a surgical candidate, so we actually did a PE gram up in the lab just to make a decision.

[Dr. Sabeen Dhand]
Was it a PE?

[Dr. Eric Secemsky]
There was a PE and it was a pretty big PE. I love angled pigtails. I'll just stick an angled pigtail on the proximal PA, usually 12-20 Fr and we do everything under DSA. If they are intubated, we can't do a breath hold and we just increase the frame rate. Usually, for the right lung, an AP and, for the left lung, a little LAO, like an LAO 30 and that's enough to make a diagnosis. The angled pigtail is nice because you can just flip it around to the LPA after and not even have to put up a wire even.

[Dr. Sabeen Dhand]
There's a lot of debate online. Do you have to use EKOS, or is an infusion catheter without the ultrasound in it, is that okay? Do you have any opinions with either of the two?

[Dr. Eric Secemsky]
Yeah, you know, we have a lot of familiarity and experience with EKOS, so we tend to still use EKOS. It's FDA approved for this indication, so we kind of taught all of our interventionalists who don't do a lot of PE how to put EKOS in so we could do it. You know, someone is available to do it every night. We tend to use that device.

Now, I got myself in a little bit of a situation because we actually looked at this in a study that was published in Chest about a year ago, comparing from national claims data. There is the caveat of whether the claim was correct or not, but you could actually identify from a billing claim whether an ultrasound assisted thrombolysis was done, or not an ultrasound guided catheter thrombolysis. We published a study that showed no difference between the two of them for in-hospital events. So, I think that gets brought up a lot.

There was a recent study called “SUNSET sPE". It was presented at VIVA a few months ago that didn't show any difference between catheter types, so I think it is up to people. I'm still a believer, to some degree, in EKOS and I'm familiar with the device, so we tend to use it. But, my other colleagues have sometimes wanted to just put in a non-ultrasound drip catheter and that's totally fine with me when they do that.

[Dr. Sabeen Dhand]
I think it comes down to familiarity. I mean, I don't feel strong either way. Our lab is very familiar with EKOS and their new units are really small. They definitely do a better job.

Yeah, even for people who don’t do it, like you said, the data shows that it's fine. The dose and duration, I know there has been a lot of different studies. You know, whether you are doing a short-term lysis or a long-term, what do you use?

[Dr. Eric Secemsky]
Yeah, that's also moved a lot. I think our standard has always been 12 hour and then again it has been a little bit variable, both in when we put in the catheters and then also with COVID, how long we want them to be sitting in the ICU with them infusing.

As you know... EKOS is invested in looking at different protocols and you can really go as short as 2 to 4 hours and the traditional ones are 12 or even 15 hour protocols. Usually we'll do 12 hours, a milligram per hour per catheter, so no more than 24 mg of tPA. Sometimes, again, we will do a shorter course. Especially if we were a little bit more on the fence about the benefits of therapy and/or concerned about any risk of tPA, we will want to limit how much tPA we give, so we will go down to a four hour protocol and just give a milligram per hour for four hours and that happens sometimes, as well.

[Dr. Sabeen Dhand]
What's your endpoint? Are you measuring pressures at bedside through the sheath or are you bringing them back down?

[Dr. Eric Secemsky]
That's a little something that me and Jeff sometimes discuss. It's funny how Jeff and the interventional radiologist sometimes want to bring them back and I always said "What are you going to do differently? Are you going to put it back in for another 12 hours?" So, my training and teaching was always that, you complete the course and you're done. As long as they're bad, which they almost always are, there is really no value at that point of doing anything more invasive. I think we got a little bit used to (with the Inari device) checking pressures before and after clot extractions. It is always nice to have that data.

If it is someone with shock with PE, so the ones that we were talking a little bit about putting a mechanical support, we'll leave a right heart cath PA line in there to manage them after they leave the lab to just watch. This is a really benign thing to do and it can be helpful, but more for the shock patient. Otherwise, we'll go back to an echo and use that really to measure pressures and RV function. That is kind of the long-term protocol, to use echo.

[Dr. Sabeen Dhand]
I'm going to come in and give you a little test question right now, Eric.

[Dr. Eric Secemsky]
Oh, no.

[Dr. Sabeen Dhand]
Yeah, I'm going to test you here. So, this always comes up on our boards. What specific heart block do you have to worry about on EKG if you are going to do a pulmonary angio, and why, and what do you do?

[Dr. Eric Secemsky]
So we used to do this for the PA lines also. If you have a bundle branch block and, particularly if you have, you know there is a left and right bundle, but if you tickle the bundle with your catheters, you could put them into complete heart block. We were told as fellows that we always had to make sure that they had the temp pacer pads in the room if they had a bundle branch block on their EKG so that you could temporarily pace them if you do end up causing a block.

I can't remember the last time I've done it. I know now it's probably going to happen on Monday. Now that I've said that.

[Dr. Sabeen Dhand]
It's funny it always comes up and they always say "Can you remember the last time that ever happened, that this left bundle branch, then you cause a right with your wire. Now that we talked about it... Good job, you passed your test. The teaching is the temporary pacing wires ,if you know before. Thankfully, it has never happened to us and I'm glad it's never happened to you.

[Dr. Eric Secemsky]
Thank you.

(9) Future Implications for Surgical Embolectomy

[Dr. Sabeen Dhand]
Now, you've mentioned these patients in shock and you have these devices to even treat these patients. Is surgery even necessary now, surgical embolectomy? Is that just not really needed for these groups of patients with our technology now, or is it still something that would be pretty mainstay?

[Dr. Eric Secemsky]
I don't think it's never going to have a role, but I definitely think that is changing a lot. We saw this again in the coronary world what was necessary for surgery and again what we could do percutaneously. Again, the interesting thing about PE patients is that they come in all flavors. You get the 30-year-old female who is smoking and taking birth control pills and just so happened to come in with a big PE, and then you get the 75-year-old who has three forms of cancer and you don't know what is going to the brain and they're here in extremis with a massive PE. Those are very different patients and they both come in at the same time and on the same day. You know, it's very likely.

So that's what's unique about PE is that it is not ageist, if you may. What we've tried to do, is we have ECMO at our institution and we cannulate for echo in our cath lab. So, especially if it's during the day, if there is someone who is really sick who could come in and we could get them on ECMO. Our hope now is to stabilize those incredibly sick ones on ECMO and then we are moving towards whether we could do clot extraction, maybe with Inari, and then let them rest in ECMO and to decannulate them versus going for an open sternotomy surgery.

Now, there are always situations, if they are particularly young, in severe shock, and they have a really central clot. Our surgeon is available and willing to take them, we will try to do that. Also sometimes, if there is a clot in transit, particularly if there is a PFO or any type of intra-atrial shunt where the clot can cross over and cause arterial embolism, we'll bring them to the OR. But even intracardiac clot is going to change and a clot in transit. Inari now got approval for clot in transit and I think that the less that we need to send people for surgery, sometimes, it's better for a lot of these patients. Not all of them, but those high-risk ones, we have more options for them. So, yeah, it's a good time in this space, because we've got a lot of development going on at the same time and they are very complementary. So, I think that what we were doing in the past is going to change in these next few years.

(10) Recommended Literature and General Advice for Pulmonary Embolism Interventions

[Dr. Sabeen Dhand]
You know, Eric, I learned a ton right now. This is super awesome. For anyone starting PE intervention, do you have any words of wisdom to the listeners out there?

[Dr. Eric Secemsky]
I think the take home here are a couple of things. Spend a little time with the literature. I think it is really an interesting space and the literature has come a long way and the data is really helpful in terms of how we practice. Jay Giri, the American Heart Association, and Jeff Barnes wrote this incredible consensus document on treatment that came out a little over a year ago in Circulation, and it has been a fantastic guide and summarizes the literature really well.

The other thing is to learn the patients really well. Endovascular techniques are not hard, as everyone knows. They're fun and they're cool. But, learn the patients. Try to get a good hold of who you think is going to benefit from these treatments. I think our gut response sometimes is to try to take as many people to the lab as we can, but unfortunately, you're going to run into people who have complications, whether it is intracerebral hemorrhage or bleeding from the groin or whatnot. So, learn the patients and know the ones who are really going to respond based on what we know about these therapies.

The last thing I'll say is that the beautiful marriage of specialties here is really unique. We are all compensated more similarly now, being employees of hospitals. I think this whole division in specialties is hopefully going to be in the past. This is a great space for everyone. My close friend is an interventional radiologist, a hematologist, and a pulmonologist taking care of these patients and I think that's such a unique part of this. So involve your colleagues when you're building the program. It is amazing how everybody complements each other.

Set up a follow-up clinic and make sure that you realize the care for these patients continues after the hospitalization, and then you are going to put yourself on the map because this is a hot field right now.

[Dr. Sabeen Dhand]
That's awesome. Eric, thank you so much. I mean, this has been truly exceptional. We're really, really happy to have you here today and, honestly, have the field of PE intervention. It's at its inception now with all these new devices and I'm really excited to see all the great stuff that you're going to come out with and help lead the field further. Thanks again for coming on with us today.

[Dr. Eric Secemsky]
Thanks, Sabeen and thanks to BackTable for inviting me to do this interview. I'm hoping to get to see you in person soon.

[Dr. Sabeen Dhand]
Absolutely. Thanks, Eric.

Podcast Contributors

Dr. Eric Secemsky

Dr. Eric A. Secemsky, MD, MSc, RPVI, FACC, FSCAI, FSVM is the Director of Vascular Intervention and an Interventional Cardiologist within the CardioVascular Institute at Beth Israel Deaconess Medical Center (BIDMC).

Dr. Sabeen Dhand

Dr. Sabeen Dhand is a practicing interventional radiologist with PIH Health in Los Angeles.

Cite This Podcast

BackTable, LLC (Producer). (2021, April 12). Ep. 120 – Pulmonary Embolization Interventions & Response Teams [Audio podcast]. Retrieved from https://www.backtable.com

Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.