Percutaneous Mitral Valve Therapies

Podcast Transcript

Announcer:

Welcome to Cleveland Clinic Cardiac Consult, brought to you by the Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute at Cleveland Clinic.

Speaker 1:

I can start off, I was intrigued by the LAMPOON and the laceration business. Can you comment about, we hear this term, "suicide ventricle," what is that? How do we handle that? And how is it relevant in the current setting, as the other folks are getting teed up with their questions?

Amar Krishnaswamy, MD:

I think there are two sort of pathologic states there in this kind of suicide ventricle idea. One is actually both our situations that Dr. Smedira and I discuss unfortunately too often. So there's work that you and he and Debbie and others have done, 10, 12, 15 years ago, looking at how the ventricle kind of changes in patients as they age. And with aortic valve stenosis, the aorta gets more horizontal. They tend to get an asymmetric upper septal hypertrophy. And then, when that happens, they may or may not have active sort of LVOT obstruction or SAM [systolic anterior motion]. So then, when we relieve their aortic valve stenosis, if they have an underlying sort of SAM or proclivity towards SAM, they can then get LVOT obstruction. And if we don't think of these things beforehand, we might be doing urgent things like a septal ablation at the time, along with the anesthetic management that comes for LVOT obstruction, to make things stable.

So that's one scenario, which, in many ways, is somewhat predictable based on assessing the preoperative data and addressing it upfront before we ever do a TAVI. So to do a septal ablation or something like that. The more difficult scenario, and it tends to be the elderly woman, who has AS, some degree of calcific mitral valve disease, ventricular hypertrophy, and then, in that setting of all of it, a small ventricular cavity. Whether or not they have a mid-cavity gradient or not, these are the patients that get really worrisome when you look at their apical views on the echo, it's an obliterative cavity and you think, "Well, maybe they're keeping that cavity a little open, because they have AS. And when we relieve the As, is that ventricle just going to become this suicide ventricle?"

So we look at those patients very closely. Sometimes, if we think maybe the hypertrophy is a little bit more isolated, not just the mid-cavity obstruction, but there's something in the LVOT, can we also do a septal ablation there? If sometimes, we can't tell, we bring them for an invasive hemodynamic study. And then, based on that, if we truly have ventricular level obstruction, we can do balloon aortic valvuloplasty. Some sense maybe that lets them ease into it a little bit, and then, if they tolerate that without a suicide ventricle, then we can actually do a TAVI and then, bring them for treatment.

Speaker 1:

Thank you.

Speaker 2:

Comments on MitraClip, just adding on to what you just said, for HOCM patients, inoperable HOCM patients, along with septal ablation or even for suicide ventricle, would a MitraClip work in that situation?

Amar Krishnaswamy, MD:

Yeah, so there's small registry data on using a MitraClip in patients that have SAM. We've done it before, again, in this same application. And the idea simply, because you grab that anterior leaflet, that's a little bit lengthy, and also it's now weighted, it doesn't tend to SAM as much. We tend only to use it for somebody who might have, maybe they've already undergone ablation, it wasn't adequate. Maybe they have LED stenting, so we can't get into a septal or the CABG and their LED is occluded, so we don't have a septal access. So we tend to reserve the clip in HOCM for a very, very niche group of people.

Speaker 2:

Thank you.

Speaker 3:

Fantastic talk and congratulations to you, Serge, and the team. Amazing, amazing work. That was one of my questions, so thanks for answering that. One comment. We put a lot of these aortic valve biologic prosthesis. Now, we're putting them in like 10-year-olds with the idea that we'll do valve in valve for forever. Same in the Mitral. And we don't have any studies that take the really long view, 30 years and look at all the different interventions. And there's data from the Mayo Clinic, from Joe Wu out of Stanford, that, when they study patients with mechanical valves, their outcome and obviously their registries in retrospect are better than with biologic prosthesis. First question, are we overdoing the use of biologic prosthesis and valve replacements is the first question. Should we put more mechanicals in?

Amar Krishnaswamy, MD:

Yeah, that's a tough question, right? This paper is showing better outcomes for the mechanical patient. It's always hard to know, because there's clearly selection biases and patients that can tolerate anticoagulation versus those that cannot and so forth. I imagine there's always a pendulum swing to these things about who gets what. And at some point, it centers appropriately. I guess, what I would say, from a 30,000 foot view, is that all these patients we have a conversation with as cardiologists, as surgeons, get the patient involved to understand where their heads are at, in terms of long-term anticoagulation from mechanical prosthetic, and also, the realities of having a mechanical prosthetic. Is it really a lifelong valve? Or is does last 20 to 25 years, at which point their only option in the current era is a redo surgery, right? So I think, once you put all of these into the equation, if they end up with a biologic valve at the index surgery, I think what's super interesting is what do we do at the next time?

Because we can't keep putting transcatheter heart valves into a space, right? It gets smaller and smaller. To your point, the long-term data is not necessarily there. In the aortic position, we're just finishing up a TVT registry on 14 and some thousand patients, in the aortic position, that has encouraging data on durability out to five years, and hopefully, it will finish up the paper and get accepted soon. But in the mitral position, I don't know what it means. Those leaflets could thrombose, those leaflets could degenerate. And so, for the 58-year-old, does it make sense to have a redo surgery now, wait until they're 70, get a valve in valve? Or do they say, "Look, I can't take three weeks or four weeks off my job. I need to earn for my family. I'll just get a transcatheter valve now, you can do a redo surgery when I'm in my late sixties and I'm retired." And I don't think the risk is going to be that much different, at least in our surgical experience here. And so, taking the patient factors into play, I think, are becoming more and more relevant.

Speaker 3:

Great answer. The data on the mechanical valves, it's very infrequent that they're re-operated on, and the data on the biologic valves, at least a third of the patients going forward end up on anticoagulation for atrial fibrillation and other reasons. So it's really a complex problem worth a heart team discussion. These severe MACs, do you look closely for liquid calcium? And if you see a lot of liquid calcium on the CTs, does it change your management? When we deal with a lot of MAC, there's a lot of material that's loose in the ventricle, where we worry about embolization. Do you do any embolization protected devices in the severe MACs, when you deal with them?

Amar Krishnaswamy, MD:

Yeah, it's a really important point. So the second point first about the embolization risk. So for transcatheter aortic valve replacement, in all of its forms, valve in valve, native, et cetera, we're huge here on embolic protection. We use it for all of our cases. Nationally, it's less than 15% based on some nuances of the data, but we feel strongly about it. So as a result, and because of the very, very low stroke rates we have in TAVR, we feel very strongly about it. Similarly, we use it not for a MitraClip and stuff, where the stroke rates are low. It's not, again, calcific disease. For MAC cases, whether it's valve in MAC, a dedicated TMVR device for a MAC patient, et cetera, we do put a cerebral embolic protection device. And as a result, have had very low to, frankly, negligible stroke rates as a result.

 So I think that's a really important point. To sort of that liquefied or calcific mass, and Serge and Rhonda and our CT colleagues, Dr. Desai and others, show us these super ugly pictures. It's hard to know how good of a scaffold that is to put in a valve in MAC, and I'm sure it's very hard, but it's also not very hard. And that's the problem. We have not done a case like that, because they've just been anatomically unsuitable from an LVOT perspective or size of the annulus or what have you. And I'm thankful for that, because I don't really want to find out about it the hard way.

Speaker 1:

And also, often, it gets hard to identify whether it is liquefied MAC, often. We don't recognize it till we hear from the surgeons postoperatively that it was indeed liquefied. Any work going on in metal valves, in terms of valve in valve, mean like a TAVR for a metal valve, if you... What's happening, you think? How do you think, 20 years down the road, that field will look?

Amar Krishnaswamy, MD:

Yeah, it's an interesting point. There are very case report kind of series' on this, to your point, Dr. Smedira, about worrying about embolization. So there are cases, both in the aortic and the mitral position, where you can go in and you can use a balloon to just fracture the prosthetic discs completely. There's a lot of embolic material that happens as a result. There are ways to address that, to some degree. You can put again cerebral embolic protection devices in. Some people have actually used a very large WATCHMAN in the aorta. That's the left atrial appendage occlusion device, again, to capture any debris that might come. And then, to put in the transcatheter heart valve into that metal frame. These are obviously extremely one-off scenarios. Having said that, I wouldn't completely discount it, only because hemodynamically, it's a great result. It's a great platform. It's a great scaffold to put a THV, but the embolic protection field is moving along at a rapid pace.

The current device we have, the SENTINEL device from Boston Scientific goes through the wrist. There's a filter in the innominate, and there's a filter in the left carotid. So it leaves the left vert open, and the pore size is still larger than we would like it to be. There are currently, and I can think of off the top of my head, five devices that are in or starting clinical trials. I'm the PI of one of them, where we put a filter device from the leg. It's basically a sock. It starts in the top of the ascending aorta, and it covers the entire cerebral vasculature, even down to the thoracic aorta. The pore size is very, very small, really just enough to let blood go where it needs to during that time. So if you think about sort of a total embolic protection, you probably worry a little less about the debris you're going to create. So to your future point, I think there's probably some hope there. At the same time, it's going to start out in very prohibitively risked patients that we would ever do it, right?

Speaker 1:

Yes. But there's hope and there's work. Any other questions?

Speaker 4:

I have a question. So Amar, like you said, it looks like, obviously, this is a complex issue, we are blessed with having experience. It looks like we having low-volume operators doing things, because it's so niche around the country. Is there any way to ensure that these are done responsibly? Or is there a concern that low-risk patients are going to be done with these devices, because it can be done? And how is that going to be monitored?

Amar Krishnaswamy, MD:

Yeah, super important question. It's frankly a very controversial question that comes up in different conferences. You can look at it really in two ways. The bottom line is, I agree with you. These are complex procedures, and it's not just from an interventional perspective, right? It's all the management that surrounds it. It's the imaging that surrounds it. It's everything else. And to have that level of expertise that we have in each of these ways, that we have the luxury of having in Cleveland Clinic, is really applicable to very few, if any, places around. Having said that, patients can't always travel, whether for financial reasons, insurance-based reasons, logistic considerations, et cetera. We know that there are patients even in Ohio that don't travel to see us, because it's too difficult for them to do so. So the ability to have some treatment options near where they live, as opposed to nothing, may still be an appropriate mental calculus for a given patient or the referring provider to make.

So I don't think we can concentrate all of these things to just a handful of places. Having said that, the most niche of the things, I do think that operators and clinicians have some degree of personal responsibility and will often refer things to more specialty centers. The device companies actually are quite responsible in this, to be honest, about both the educational programs that they have, as well as deciding where things like transcatheter mitral valve replacement or on the tricuspid side, these therapies go to, to be analyzed in the real world setting, before disseminating more diffusely. So I think you could see the answer on both sides of the coin.

Speaker 1:

Thank you. This is actually, I'm very thrilled with the crowd presence and the engagement. And very high quality presentation. We often hear from outside speakers, but we have some major superstars here. We should always remember that. Thank you, Amar, for doing this.

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