Since the approval of the first transcatheter aortic valve replacement (TAVR) device in 2011, the procedure has grown steadily in popularity. We spoke with Dr. Matthew Sherwood, co-director of the structural heart program and cardiac catheterization lab at Inova Heart and Vascular Institute, as well as a member of the American College of Cardiology's Interventional Section Leadership Council, about the adoption of this procedure, and to provide a look at its future.

HCB News: From a big-picture perspective, can you tell us a bit about what TAVR entails, and how it compares to the conventional surgical aortic valve replacement (SAVR) treatments it has largely replaced?
Dr. Matthew Sherwood: Transcatheter aortic valve replacement, or TAVR, is a revolutionary treatment for aortic stenosis. Instead of requiring conventional surgery, which would be open heart surgery, a sternotomy, and a five- to seven-day stay in the hospital with four to six weeks of recovery, transcatheter aortic valve replacement is where you actually placed the valve on a catheter through the femoral artery, up to the heart, and then [implanted the valve]. Instead of taking four to five hours for surgery, the procedure takes about an hour.

Most of our patients go home within one day and only stay one day in the hospital. Some stay two days, and then most people are back on their feet doing normal things, even going to cardiac rehab, within one to two weeks.

HCB News: Have the TAVR devices themselves evolved in meaningful ways over the last several years?
MS: We're currently on our fourth-generation devices from the two major manufacturers, Edwards Lifesciences and Medtronic. Edwards makes the Sapien and Medtronic makes the CoreValve and the Evolut PRO+.

Both valves have gotten significantly better. They're able to be delivered on smaller delivery catheters. Initially, it was between 18 and 22 French, which are large catheters, and now it's actually gotten down to 14-French sizes, which are significantly smaller catheters, and that actually is more inclusive. That means more people can actually have TAVR, whereas before some people were excluded, because their femoral artery and iliac arteries weren't large enough to accommodate the device and the delivery system. So that's one thing that's made a huge difference.

And then the devices themselves have gotten easier to deploy, and they all now have what's called a sealing skirt, [which is] some tissue or fabric at the bottom of the device that helps it to seal in the aortic valve annulus, and that helps it to leak a lot less and helps performance. And so that's considerably better.

Now, 97% of patients can be done that way.

HCB News: What is the reimbursement situation like for TAVR?
MS: It's covered by Medicare and the vast majority of patients that we do are over the age of 65. And it is widely covered by private insurance as well, though there are some pockets of patients that aren't well covered. Specifically, the younger-than-65 bicuspid patients, sometimes they're not as well covered, but the reimbursement situation is good. It's well covered.

The reimbursement has decreased over the years since its inception, but there are situations in which the providers recognized that some patients have multiple medical comorbidities and so their reimbursement slightly increases in those cases. But as TAVR has grown, reimbursement has seen small decreases.

HCB News: What were some of the watershed moments in the history of TAVR adoption and clinical validation, or viability?
MS: Two of the watershed moments were the very first Edwards Lifesciences trials, PARTNER II and PARTNER 3. [In] the initial PARTNER trial, TAVR was compared with, for inoperable patients, medical therapy. This was one of the first times where a medical device showed remarkable decrease in mortality as compared with medical therapy. So that was a huge moment, where we saw that TAVR actually saved lives in a dramatic way. Medtronic followed up with a trial that was similar.

The next seminal moments came when the population was expanded from just high and prohibitive surgical risk patients to intermediate participation. Trials were published showing that with intermediate risk patients, TAVR was just as good as surgery in terms of outcomes, and gave us a hint that for some patients, those who underwent transfemoral TAVR, which is the vast majority of them, [it] could be better in the short term than surgery.

And finally, the most recent and most seminal moment was the low-risk TAVR trials. Specifically the PARTNER 3 trials showed that actually TAVR in the short term [showed] significantly better outcomes than surgery for patients at low risk. And that was a big change, because that not only kind of opened the gates for doing TAVR on low-risk patients, but it increased the awareness that TAVR could be done in many, many patients, probably the majority of patients with aortic stenosis.

HCB News: From a technology standpoint, what kind of imaging or operating room capabilities are required for a facility to introduce TAVR to their patients?
MS: Usually what we used was something called a hybrid operating room, an additional operating room that has fluoroscopic equipment within the room, so that the procedure can be done with fluoroscopy. But if there was a complication that requires surgery, that surgery could be immediately performed with very little delay. Nowadays, we do our procedures in a hybrid OR, but there are many places that do their procedures in a cath lab with availability to transfer the patient to an OR quickly if there's a problem. So, you need a state-of-the-art cardiac catheterization lab for TAVR with surgical backup.

HCB News: Do you have a sense of how TAVR might be different in another 10 years or so?
MS: I think we've already started to see that TAVR has now supplanted surgery as the default option for patients with aortic stenosis, certainly for those over the age of 65. I think we'll continue to see increases, and what we'll be very excited to see is whether the TAVR valves have the same durability as the surgical valves, and that's something we're waiting on.

As we go forward, we may see valves that are slightly smaller, so they may continue to decrease the size of the delivery system. They may start to try to devise ways to make the TAVR valves more durable, whether that includes different materials or coating the leaflets with different material.

One of the one of the things that they've done so well is try to reduce the leaks around the TAVR device. Will there be changes to what we call lifetime management for younger patients? Will they make the devices so that the coronary access is more amenable in devices that have larger cells within them, so that you can get to the coronary arteries all the time? Those are the kinds of questions that are coming up.

HCB News: Are there other key considerations for providers to look at before adopting TAVR?
MS: Yeah, that goes with the durability issue. And the question is, are TAVR valves as durable as surgical and surgically-implanted valves? There's no reason to think they wouldn't be. They're made of the same materials, with similar design. But TAVR valves have to be crimped and then expanded in place in the aorta, so there's a question of whether that process might decrease durability. What we're waiting for is, honestly, data to say that TAVR valves are as durable or even more durable than surgical valves. Depending on their durability, that will shape how we treat these younger patients. I think it's easy to say for a patient 70 and older that putting in a TAVR valve is the right thing because [they] last between 10 and 15 years. Patients at age 65 will certainly have another valve procedure in their future.

HCB News: What resources are available to medical professionals interested in learning more about the procedure?
MS: There's lots of information available online from both Medtronic and Edwards Lifesciences providing information about the TAVR procedures in general. As you might expect, there's lots of information in the literature that can be easily looked up on websites like PubMed or Google Scholar, etc., where people can get a lot more information about the evidence behind using TAVR. There's information on many hospital's websites, like our website, and certainly information from the American College of Cardiology and the American Heart Association on these procedures. There are also educational courses given, as well as webinars.