Transcription:
Treating Mitral Regurgitation with Transcatheter Mitral Heart Valve Procedures

Melanie Cole: Welcome to Better Edge, a Northwestern Medicine podcast for physicians. I'm Melanie Cole and I invite you to listen as we examine treating mitral regurgitation with transcatheter mitral heart valve procedures. Joining me is Dr. James Flaherty. He's an interventional cardiologist and the Medical Director of the Coronary Care Unit at Northwestern Memorial Hospital and an Associate Professor of Medicine in Cardiology at Northwestern University Feinberg School of Medicine. Dr. Flaherty, it's a pleasure to have you join us today. Tell us a little bit about the prevalence of mitral regurgitation. What are you seeing in the trends?

Dr. James D Flaherty: Mitral regurgitation is the most common serious valve disorder there is. It is more common than aortic stenosis, which a lot of people already know much about. It can be a very severe condition. It can lead to heart failure and a lot of symptoms that come with that. It is associated with mortality in those that go untreated. And it is also increasing as individuals get older. After you reach your sixth decade of life, the prevalence can go anywhere from five to ten percent of significant mitral regurgitation in the US population.

Melanie Cole: Well, thank you for that. So at Northwestern Medicine, how are patients evaluated for a transcatheter mitral valve replacement or repair?

Dr. James D Flaherty: Our experience with transcatheter therapies mostly came out of our TAVR experience that started around 2007. And we formed a valve clinic, which is a multidisciplinary clinic that includes interventional cardiologists, cardiac surgeons, nurses, uh, radiology specialist and some others. And in general, we evaluate patients mostly on the same day in both interventional cardiology and cardiac surgery. And we do all necessary testing at the same time whenever we can to try to make it convenient for patients to get everything done as efficiently as possible.

Following that, we have weekly interdisciplinary meetings where we review all the data and imaging for all the patients, and we try to make a consensus recommendation as to the best way a patient may be treated.

Melanie Cole: Well, then speak about the clinical indications for a TMVR.

Dr. James D Flaherty: So for mitral regurgitation, the gold standard is surgical mitral valve repair and our surgeons have been doing that for several decades and have had great outcomes. But there are some patients who are at higher risk for open-heart surgery. Therefore, they're considered primarily for transcatheter therapies. The most common being something known as TEER, that stands for transcatheter edge-to-edge repair. The most commonly known device used for this is the MitraClip device and it is based on an old surgical procedure called the Alfieri stitch whereby the mitral valve is stitched together in the middle to reduce the amount of regurgitation. That procedure was turned into a transcatheter procedure where you could achieve a similar result with catheters through the groin, uh, as was done surgically. Now that started off in patients that have what's known as degenerative or primary mitral regurgitation, which means there's a problem with the leaflet. It's usually prolapsed or somebody says flail if it's extremely prolapsed.

There's a second group of patients that's emerged. And those are known as patients with functional mitral regurgitation or secondary mitral regurgitation. And that's a leak that's caused by a cardiomyopathy or in somebody who has heart failure, either due to a weak ventricle or an old heart attack. And there was a big trial on this called the COAPT trial that came out a couple of years ago that showed that the MitraClip procedure in carefully selected patients on optimal medical therapy has significantly improved survival and much less hospitalization after this procedure. So those are the two main groups that are considered for transcatheter mitral valve repair

Melanie Cole: Dr. Flaherty, as you describe the procedure for us, I'd like you to expand on any technical considerations you'd like to share with other providers. And then also tell us how the PASCAL CLASP differs from MitraClip, which, you know, you discussed a little bit of the evolution. So tell us what's new and how do they differ?

Dr. James D Flaherty: So in general, most patients with significant mitral regurgitation that are being considered for treatment with either a transcatheter device or open-heart surgery, most go undergo a transesophageal echocardiogram. And with that imaging, measurements can be made on the leaflet length and other features of the valve that can really inform the group as to whether a patient is a good candidate for a transcatheter procedure. The other critical piece is the risk assessment if they were to undergo open-heart cardiac surgery.

As I mentioned earlier, the first kid on the block was the MitraClip, uh, started off with the EVEREST trials and then the COAPT trial that I mentioned as well. The PASCAL device is the device that is being tested out in the CLASP trials. And this is a device that aims to achieve a similar repair on the valve that the MitraClip does by stitching the leaflets together in the so-called Alfieri fashion.

There are some technical differences in the hardware of the devices, but essentially, they're looking to achieve the same thing. They both are done through what's called a transseptal puncture, which means you'd take a needle in the right atrium and crossover into the left atrium, which gets you right above the mitral valve. And you work the device down to the leaflets and then use the arms of the device to literally stitch the valves together. So the devices behave a little differently. There they have a little different profile and size and flexibility and visibility on imaging as these procedures are all done under continuous transesophageal echocardiographic monitoring, but they're seeking to achieve the same thing. And the studies will tell us, we hope if one device or the other, uh, achieves a better clinical outcome.

Melanie Cole: What are some of the challenges of these procedures?

Dr. James D Flaherty: Once you have a program going, that's always a challenge to get things started and get a nice flow we're getting with cardiac anesthesiology and echocardiography and interventional cardiology and cardiac surgery. So there's always a lot of challenges in getting a program up and going and the workflow and the coordination. But after you've achieved that, there's certainly technical challenges to the procedure's learning curve. The procedures can tend to be longer, in some cases lasting over two hours. For the patients in general, this is done almost always under generally anesthesia to be able to do the TEE monitoring the whole time. So a patient has to be suitable for general anesthesia for a couple hours. That makes it pain-free in the most part.

The risks of the procedure, at least for what I've referred to as TEER such as MitraClip, they're actually quite low. They're much lower than with the TAVR procedure that's used on the aortic valve as a comparator. Like any procedure that uses large devices in the vascular system, there's always risk of bleeding or other mechanical injury. But in general, uh, I think the risk profile of the procedures is very acceptable.

Melanie Cole: Well, thank you for that. So what are the current recommendations for post-procedure antiplatelet or anticoagulation? What are you doing for patients afterward?

Dr. James D Flaherty: The standard has been like a lot of devices used in the cardiac system, a standard emerged years ago to use what's known as DAPT and DAPT stands for dual anti-platelet therapy. And that most commonly means a low dose of aspirin 81 milligrams and clopidogrel 75 milligrams. This is the same regimen that's been used really now for a couple of decades after coronary stents. So a lot of trials in the valve space have adopted. That is kind of the default standard after device procedures like the MitraClip. So that's the default is at least three months of dual antiplatelet therapy.

Now a lot of patients with mitral regurgitation or other valve problems also have concomitant atrial fibrillation, which is an indication for an oral anticoagulant, such as warfarin or one of the newer agents known as DOACs. Um, if a patient has an indication for a different blood thinner, then the regimen is modified to align with that indication.

Melanie Cole: And Dr. Flaherty, tell us a little bit about any clinical trials that are prevalent at Northwestern Medicine, which transcatheter mitral clinical trials are you most excited about?

Dr. James D Flaherty: So there's a few different groups of trials in the mitral space. We've mostly been talking about the transcatheter edge-to-edge space, uh, and that includes the PASCAL CLASP trials, which is comparing the PASCAL device, which is a newer device versus the MitraClip device in a couple of different scenarios. One is extreme risk patients that have degenerative or primary mitral regurgitation comparing those two devices. The other group is those with functional or secondary mitral regurgitation. So those are two separate trials based on the etiology of the mitral regurgitation, comparing the standard device versus the newer device.

There's another trial that's pretty exciting in the TEER space, that's the REPAIR MR trial. And that's looking at patients who have degenerative or primary mitral regurgitation and are only at intermediate risk for cardiac surgery. So they're not low risk, but they're not high risk either. That's a randomized trial comparing TEER with MitraClip versus open-heart mitral valve repair. That's a kind of a new concept looking at these kinds of devices and procedures in intermediate risk patients.

Now, what we haven't brushed on yet is what we talked mostly about is different ways to repair the valve. Um, but what we haven't talked about is actually implanting a new valve over the existing valve, and that can occur in generally two scenarios. The most experienced is something called mitral valve-in-valve. And that is when someone has had previous bioprosthetic mitral valve implantation, but now years later, that valve has failed either because now it's leaking a lot or it's become stenotic and a patient is developing recurrent symptoms.

And we can most often put a valve that was designed for the aortic space, a TAVR valve, through a transseptal puncture. We can put a valve inside that existing valve without opening the chest going through the groin. Now, this is FDA approved for those that are considered at higher extreme risk for redo cardiac surgery. But we also have a registry, um, it's led by Chris Malaisrie, one of our cardiac surgery leaders, looking at this procedure in those that are deemed intermediate risk for redo cardiac surgery. So that's an exciting advancement for those that have had valve replacement in the past.

The final silo of patients are those that have not had repair or replacement in the past, but are at higher extreme risk with significant mitral regurgitation. And those are the transcatheter mitral valve replacement trials. And we have a few of those that we're participating in. Most in the past have gone through what's known as the transapical approach, which is a procedure where a surgeon makes an incision in the chest to open up the apex of the left ventricle and get access to the mitral valve that way. Some of the newer trials are looking at transeptal mitral valve replacement through a catheter-based system, and we're actively screening patients for some of those trials and we're really looking forward to it.

Melanie Cole: What an exciting time to be in your field, Dr. Flaherty. As we wrap up, why should referring providers consider Northwestern Medicine for their transcatheter mitral replacement repair procedures? And tell us a little bit about how your outcomes have been.

Dr. James D Flaherty: I think what patient and providers should be looking for is a well-developed team. We always wanted to make sure that a patient gets a full evaluation for either open-heart surgery or the best transcatheter option if open-heart is not a good option or they're looking for a less invasive option. So I think with our years of experience in the transcatheter, and especially in the surgical realm for valve disease, I think patients are going to get a really thoughtful full evaluation. And I think that's one of the strengths of our institution. Dr. Pat McCarthy and Dr. Charles Davidson have been leaders in these fields for years and bring wisdom and experience to the team to make it flow the right way.

Our outcomes. I don't have numbers in front of me, but, uh, again, the so-called TEER procedure such as the MitralClip is very safe. So safety outcomes are very good and all of our outcomes are carefully captured in what's known as the TVT registry, where we carefully follow any complications, long-term success on both the clinical and the valve side. So we've had great clinical outcomes with a very good safety margin so far.

Melanie Cole: That's great information and such an interesting topic. Thank you so much, Dr. Flaherty, for joining us today. To refer your patient, you can call (312) NM-HEART, or you can head over to our website at heart.nm.org to get connected with one of our providers.

And that concludes this episode of Better Edge, a Northwestern Medicine podcast for physicians. Please remember to subscribe, rate and review this podcast and all the other Northwestern Medicine podcasts. I'm Melanie Cole.