COMMENTARY

Transcatheter Mitral Valve Replacement: State of the Heart

Michael J. Mack, MD; Alec S. Vahanian, MD

Disclosures

March 26, 2018

Michael J. Mack, MD: Hello. My name is Michael Mack, and I am the director of the cardiovascular service line at Baylor Scott & White Health in Plano, Texas. Today I am joined for this very interesting session by an old, longtime friend of mine, Professor Alec Vahanian, who is professor of cardiology at the University of Paris VII. Alec, welcome.

Alec S. Vahanian, MD: Thank you, Mike.

Dr Mack: We are going to discuss the field of transcatheter mitral valve replacement (TMVR) today. Alec, let's talk about TMVR and the differences between TMVR and transcatheter aortic valve replacement (TAVR) or, as you say in France, TAVI (transcatheter aortic valve implantation).

Slower Progress Than TAVR

Dr Vahanian: Thank you. May I correct you? The name "TAVI" came from the United Kingdom. We wrote a consensus statement in 2008[1] with a very good surgeon, Neil Moat, who proposed "TAVI." You should pay homage to Neil, who is a friend of yours.

It is complex and will take more time. Why? Because physicians have to learn about the disease.

To come back to the topic, we cardiologists are a bit ignorant about the complexity of the mitral valve. We thought that it was just like the aortic valve—you have the annulus, some curves, but that is it. With the mitral valve, the major components are the annulus, the valve, the subvalvular annulus, and the left ventricle. We have to work with this very complex thing.

This is a very good occasion to remember what your colleague Alain Carpentier said: When describing mitral valve disease, you should speak about anatomy, lesions, and function. We do not do this correctly. Echo reports should describe this, and when choosing an intervention, we should take all of this into account.

Dr Mack: A lot of people think that this is the same as the aortic valve in terms of expectations, yet it seems to be taking a lot longer and is a lot slower. Is it unrealistic to expect progress like we saw in the aortic so quickly?

Dr Vahanian: I hope it will happen, and I am quite confident it will. But as we just said, it is complex and will take more time. Why? Because physicians have to learn about the disease in order to avoid making huge mistakes. When we discuss mitral, we also discuss tricuspid, right ventricle, et cetera. The techniques need more skills, and the imaging is more complex. Surgery for mitral valve regurgitation (MR), when the valves are amenable to repair, does such a good job that the bar is pretty high. If your colleagues continue to do a good job but all the surgeons move to TAVR, no one will be left with expertise in mitral valve repair, and there will be more room for the interventionalists.

TMVR Devices

Dr Mack: There is one device approved in the United States for transcatheter therapy in the mitral valve, and that is MitraClip. Additional devices are approved in Europe. Can you give us an idea of what the landscape is there and what practitioners are using?

Dr Vahanian: In Europe, CE Mark is given mostly on the basis of safety. We have MitraClip, the annuloplasty [system] Cardioband, the coronary sinus pseudo-annuloplasty Carillon® device, and the NeoChord. I am not aware of any others with the CE Mark.

After CE Mark, there is also the national regulatory agency and you have a wide discrepancy [across Europe]. For example, in France, we can use MitraClip only for primary disease and we cannot use the others in routine practice—only in clinical trials.

Dr Mack: You were kind enough to host me at the Hôpital Bichat-Claude Bernard and in your cath lab a number of years ago, where we did an annuloplasty procedure together. You and Professor Maisano were there, so it was an honor for me to be there. How are these devices besides MitraClip progressing?

Dr Vahanian: Many patients were treated. To my knowledge, the Cardioband has been used in about 500 patients, but reports are on a more limited number. The Cardioband is widely used in Germany, used a little bit in Switzerland, and only used in trials in other countries. There is also a registry, and the randomized trial will start in the United States soon. It seems that all these devices are quite safe.

In terms of efficacy for reduction of MR, I think the results we have from annuloplasty are equivalent to the MitraClip. So it works very well. I do not want to compare, but they are effective. The coronary sinus pseudo-annuloplasty Carillon device It seems to be less effective. To my knowledge, there are relatively few peer-reviewed reports with NeoChord. It seems that in very well-selected patients with localized P2 prolapse and nonsevere annular dilation, results are good. Other devices, such as the ARTO TMVR system, are being studied, but we need more data.

Dr Mack: Is it fair to say that leaflet devices, such as the artificial chords and to some degree MitraClip and PASCAL, will be used mainly for primary or degenerative disease and the annuloplasty devices mainly for secondary MR? Or is that too simplistic?

Dr Vahanian: The idea is to try to find the appropriate combination according to anatomy and function. From experience, we know that annuloplasty should be used, except in rare cases. On top of annuloplasty, leaflet devices are mandatory for primary MR. There were interesting preliminary results from Milan[2] showing that MitraClip plus annuloplasty was more effective than annuloplasty alone in secondary MR, but we will have to reproduce that. Experience with the NeoChord device is quite limited, and we should aim for combinations and reproduce what you are doing in surgery, which works well.

Secondary MR Is Complex

Dr Mack: The clinical unmet need has been secondary MR. It has never been demonstrated that correction of secondary, or functional, MR either prolongs life or improves quality of life for a significant period. What is your feeling? Do you think correction of MR will make a difference for patients?

Dr Vahanian: Secondary MR is a wide landscape. We do not know how many patients have it because we do not have good prospective studies with echo definitions separating primary from secondary MR. We are putting several sorts of patients in the same bag. Secondary MR may be due to ischemic or nonischemic left ventricular (LV) dysfunction, and they are not exactly the same. We have patients with relatively localized scar of MR, severe MR, but an LV that is not catastrophic. Another group, which is underevaluated, is patients with some pure annular dilatation, longstanding atrial fibrillation/MR with preserved ejection fraction (EF). We should not put everything in the same basket. We are mixing together patients with EF 10%-20% and patients with EFs > 30%. This is not the same disease. We are also putting in the same bag, patients with predominant MR and those who also have very severe tricuspid regurgitation (TR) and right ventricular (RV) dysfunction. We know RV dysfunction is very bad. We need to be more systematic, separate the different kinds, and then evaluate them correctly.

There is a slight discrepancy between the American guideline[3] and European guideline[4] regarding the threshold for severity. If you read both guidelines carefully, they do agree. The US guidelines prefers to move back and use the same threshold for severity, and ours says to keep the previous one. But we are not happy with that, and you said exactly the same thing. We need to do more work and probably do new natural history studies with good quantification because we are relying studies that are more than 15 years old.

Tricuspid: The 'Forgotten Valve'

Dr Mack: You mentioned TR. The tricuspid has been called the "forgotten valve," and it seems like recently, it has been found and that it is no longer forgotten. A lot of the transcatheter devices that were designed for the mitral valve are also being used for the tricuspid. Could you give us an overview of the transcatheter treatment of TR and how you see that field progressing?

[TR] is a much more complex disease that should be restricted to very experienced heart valve centers.

Dr Vahanian: It is hard to give crude numbers. I heard that in Germany, over 500 patients were treated using MitraClip. Unfortunately, peer-reviewed reports concerned only 50 patients,[5] so it is a big gap. It seems doable but relatively difficult, because imaging is an issue. MitraClip results in a moderate decrease in TR and some degree of functional improvement. Cardioband was used in about 50 or more patients. We do not have a peer-reviewed report of the case series, but it seems very logical. It seems the closest to what you are doing with surgery, with its almost complete rings.

There are reports on other devices with balloons put in the middle of the orifice, such as FORMA.[6] There are a couple of other initiatives which are more or less reproducing surgery. For the time being, we have imperfect devices and we are treating patients who are far too advanced in their disease. We are treating patients with huge annular dilatation and with very poor RV function.

The big challenge is to separate patients whose RV can improve and remodel from patients who are out of solutions for their RV. That is a big issue. You do not want to do treat patients with normal RV. You need to eliminate patients with severe pulmonary hypertension. Patient referrals for TAVR are usually okay. Very few are futile from the cardiac standpoint. With MR, more patients are really futile from the cardiac aspect. In TR, there are so many patients and often the referring provider forgot to look at the left side, so you have to fix the left side as well. It is a much more complex disease that should be restricted to very experienced heart valve centers.

Dr Mack: You mentioned futility. In patients with aortic valve disease, futility is based on comorbidities and other conditions. They are dying with aortic stenosis, but not of aortic stenosis. I think futility in both mitral and tricuspid disease is due to advanced LV and RV disease and dead ventricles. It does not matter whether you correct the TR, because the patient is not going to get better. Is that a fair summary?

Dr Vahanian: I agree with you; that is a very fair summary. But the tricuspid has a nice future if the mitral intervention shows to be effective and if we are able to prove effectiveness in intermediate- plus high-risk patients. Then we will be willing to tackle the tricuspid when treating the mitral, as you do during surgery. At this time, if we are addressing patients with less severe tricuspid disease, we probably will be able to do a very good job on both.

Future of Transcatheter Therapy for Mitral and Tricuspid Disease

Dr Mack: Go out on a limb and make a prediction. In 5 years, where do you think we will be with both mitral and tricuspid disease from a transcatheter therapy approach?

We find that barriers are not regulatory, but that adoption is directly related to reimbursement.

Dr Vahanian: I do see that mitral interventions will go up, no doubt. Within 2 years, we will have the results of the French randomized trial and a couple of months later the results from COAPT, comparing medical therapy with MitraClip in secondary MR. Let's hope that both will throw out the same messages. We will also have RESHAPE-HF, and so we will know a little bit about where we are going.

If they are positive, it will really open the door to many patients. If they are negative, or if one is positive and the other negative, we will have to discuss this again. With technical improvements, and new devices such as PASCAL and combination therapy, we are probably going to increase [use] in patients with primary disease—but not dramatically. For tricuspid interventions, I think the progression will be very slow.

If I can give you a European, especially French, point of view, we must solve the reimbursement problem. Having good trials and having CE Mark does not give us the money to use the devices.

Dr Mack: You are right. We find that barriers are not regulatory, but that adoption is directly related to reimbursement. Both the professional societies in Europe and the United States have made proposals now for valve centers of excellence and for national networks of valve centers. Do you think over the next 5 years that these advanced therapies will be used mainly in comprehensive centers of excellence?

Dr Vahanian: At least speaking from my country, I think this should happen. These centers should be medical and surgical centers at the minimum, with very well-trained imaging people, all the imaging facilities, and above all the heart team working all together. In the mitral field, it should include the transplant team. The sickest patient should be discussed with the transplant team. If the goal is just to delay transplant for 1 or 2 months, they should not do this therapy. For the rest, I think the heart valve center of excellence should be there. We will do our best to do this within 5 years. Do you know of any thresholds to define a center of excellence?

Need for Comprehensive Assessments

Dr Mack: There are definitions of thresholds in other fields, such as stroke therapy, trauma, etc. I do not think we know what those thresholds are yet in valvular heart disease. Part of the issue, and it is more important in mitral and tricuspid than aortic, is that it's not the procedures or the numbers of procedures; it's the clinical decision-making, patient selection, and quality of the imaging. We see many patients referred in with "severe" MR and it is really mild, or they are not on medical therapy and you put them on medical therapy and they get better. It is about much more than just the procedure. It requires a comprehensive assessment of a patient with a multidisciplinary team. Do you agree?

It's not the procedures or the numbers of procedures; it's the clinical decision-making, patient selection, and quality of the imaging [that make a center of excellence].

Dr Vahanian: I do agree. Like Grayburn and Wang and their colleagues[7] did in the United States, we completed a study[8] with 600 primary care physicians and cardiologists. We saw how doctors are lagging behind the guidelines. It is not that bad for primary MR, but it is very poor in secondary MR. There is no use of medical therapy to start with, and when patients fail with medical therapy, there is not even a consideration of something else. We have to convey better messages in terms of education, echoes, screening, and use of therapy. We should start with medical therapy in secondary MR, but not keep the patient on pills for years or cardiac resynchronization therapy (CRT). It was shown that if you implement CRT, it is very good. If CRT fails to improve MR, you should not wait 2 years before treating the patient because he will die.

Dr Mack: I totally agree. Alec, this has been an absolutely fascinating discussion. The field is so interesting and intriguing, and there have been so many developments. We could carry this conversation on all day today, but unfortunately we are out of time. I learned a lot from this, and I hope that our viewers did too. We have been close friends for many years and I look forward to working with you many years in the future. Thank you very much, Alec.

Dr Vahanian: Thank you, Mike, for the invitation; it was great.

Dr Mack: I hope you found this discussion very informative, and watch for more progress in this very exciting field.

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