Transcatheter Mitral Valve Intervention: It is exciting to do these procedures to replace or repair a valve, and now, for TAVR, to do so in an awake patient.

28 July 2016

Interview Dr. Ted Feldman MD, Director, Cardiac Catheterization Laboratory – NorthShore University HealthSystem, Evanston, Illinois

Transcatheter Mitral Valve Intervention: It is exciting to do these procedures to replace or repair a valve, and now, for TAVR, to do so in an awake patient.
Can you tell us about your center and history with the mitral valve?

NorthShore’s valve program goes back to the beginning use of MitraClip (Abbott Vascular) in 2003. We did the first MitraClip procedure in the United States, and I have been the principal investigator for the EVEREST (Endovascular Valve Edge-to-Edge REpair Study) MitraClip trials. Prior to the MitraClip, I was involved with the Inoue balloon (Toray Medical) mitral valvuloplasty trial, going back to 1990, which became the only device approved for mitral valvuloplasty. It remains the standard therapy for mitral stenosis worldwide. 

What studies are you currently involved in? 

We have an investigator-sponsored investigational device exemption (IDE) study for using the Edwards transcatheter aortic valve replacement (TAVR) device in calcific mitral stenosis, MITRAL (Mitral Implantation of TRAnscatheter vaLves), headed nationally by my colleague Mayra Guerrero. We are also participating in the Tendyne (Abbott Vascular) mitral valve replacement trial. I am anticipating several trials for other mitral repair devices that are in use internationally, including the Carillon Mitral Contour System (Cardiac Dimensions) and the CardioBand System (Valtech Cardio). Ongoing is the COAPT trial (Clinical Outcomes Assessment of the MitraClip Percutaneous Therapy for Extremely High-Surgical-Risk Patients). The trial was originally intended to randomize 430 patients, but an interim analysis several months ago showed that the event rate was not high enough to reach a conclusion, so the enrollment has been extended. It will be another several months for COAPT to finish enrollment.

Are there advantages to mitral valve replacement vs repair? Will one or the other dominate in the future?

The appeal of mitral replacement is the promise of complete elimination of any residual mitral regurgitation (MR), while the appeal of the repair technologies is established safety and relative simplicity. How this balance unfolds will take at least several years.

What are some of the challenges of transcatheter therapy in the mitral valve?

On the positive side, catheter therapy has been successfully applied in patients who are at prohibitive risk for surgery. That plus has already been realized. The larger challenges are that the dedicated mitral devices are currently larger profile. Almost all of the successful procedures have been done transapically. For the long haul, we can all expect that these procedures will have to be transseptal to truly reach their full promise in terms of treating larger numbers of patients. It is not just a matter of decreasing the bulk the devices. Transseptal delivery is harder in terms of geometric alignment of the devices, in terms of achieving a stable position and the correct axis for the device to sit properly. From the apex, you have a short, straight shot, and getting the devices to align is much more achievable from a technical standpoint, but, of course, it is harder on the patient to have an apical rather than a transseptal procedure. One of the biggest challenges, where the magnitude of the challenge has been bigger than anticipated, is the potential for the mitral devices to protrude into the left ventricular outflow tract and obstruct aortic outflow. Device protrusion into the left ventricular outflow tract and obstruction of aortic outflow has turned into an important limitation of many mitral replacement devices. The fact that this has been recognized has forced the rapid development of CT scan model planning for these procedures. CT scanning, as with TAVR, has become integral to the planning of mitral procedures.

What are the next steps for developing mitral replacement devices?

In terms of development, all or most of the companies that are involved in this effort are working to develop effective transseptal delivery systems. It is a challenge to make a large-caliber device predictably deliverable from the left atrial side, rather than the left ventricular side.

How do you see the heart team organizing around the mitral patient?

The heart team has developed, but in an evolutionary manner. You don’t just put together a roster of interested parties, instantly sit down in a room, and have a functioning heart team. In our program, the heart team started many years ago with patient selection for the SYNTAX and EVEREST trials. We now have a Wednesday afternoon weekly heart team meeting, where we review with our research and clinical nursing team, and our interventional and surgical physicians, a list of aortic, mitral, and left atrial appendage patients that are all undergoing screening and procedure planning. In many respects, that is the easiest part. There is an ongoing interaction among the team members at many stages. It becomes part of the whole practice. Our interaction with the surgeons has evolved and in terms of decision-making, it’s not only that it is team-oriented, but that it is a process. Decisions are not usually made in one step, because the evaluation takes face-to-face visits with both the interventional and surgical physicians, and the imaging has to be reviewed. So we need to do whatever it takes to get those major components all to drive toward a decision about best therapy for an individual patient.

What evolution do you see for the team during the procedure itself?

For TAVR, the surgeon and interventional physicians are required to be physically present for Medicare reimbursement. From one program to another, the degree to which both specialties are truly involved in the procedure varies. In our own practice, we have made a serious effort as the procedure has become less surgical to get our surgeon colleagues involved in some of the interventional steps, so that everybody can truly participate in the procedures. On the mitral replacement side, the procedures now are predominantly apical, so there is an obvious clear involvement of the surgeon. This is a work in evolution, so we will see how this changes as the mitral procedures become more percutaneous and less surgical. That is going to be a long road.

Any final thoughts?

Patients who either had no option or were facing an open sternotomy procedure are now being treated with increasing frequency with a completely percutaneous procedure, a short hospital stay, and a remarkably short recovery time. It is exciting to do these procedures to replace or repair a valve, and now, for TAVR, to do so in an awake patient. For mitral, we are at the beginning of that journey, but with a lot of that same promise, typically validated on the one-month follow-up visit where these patients come for follow-up and they are transformed, without having had open surgery. 

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