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By Amanda Pedersen

Senior Staff Writer

The topic of the transcatheter valve replacement (TAVR) market, also known as transcatheter valve implantation (TAVI), brings to mind the classic Dr. Seuss story, "Oh, the Places You'll Go."

Looking back to 2011 when Edwards Lifesciences (Irvine, California) brought its first-generation Sapien valve to the U.S. market, the TAVR/TAVI field has grown and evolved in ways most people in the industry never could have predicted.

Today, there are at least eight companies developing TAVI devices and with Medtronic's (Minneapolis) big news last week that the FDA approved its CoreValve system in the U.S. (Medical Device Daily, June 13, 2014) there are officially two companies with TAVR technology available in the U.S.

Traditionally the procedure has been indicated for patients with severe aortic stenosis who are considered high risk for surgery. But there is an emerging trend toward treating a younger and lower-risk patient population with transcatheter valves. In a recent report from Canaccord Genuity, analyst Jason Mills said expansion into intermediate risk patients represents one of the key drivers of growth for the global TAVR market.

Mills released the report following a three-day conference on transcatheter valve therapies in Vancouver. He highlighted five of the hottest topics in TAVR for 2014, but noted that the single, important underlying theme was the market's continuing shift toward treating a lower-risk patient population. "Our takeaway is that this shift is already occurring in real-world clinical practice," Mills said.

In response to this shift, Mills said conversations with key opinion leaders at the meeting indicated that physicians will be less focused on acute outcomes over the next several years and more focused on longer-term device durability.

"As TAVI evolves from a technique fraught with risks to a stable and predictable procedure, our research shows a conspicuous trend toward the treatment of lower-risk patients who may also be eligible for surgical intervention," Mills said.

The concern, he added, is that this shift toward treating lower-risk patients is taking place in the absence of data from well-controlled, randomized clinical trials because results from PARTNER IIA or SURTAVI won't be available for a while longer.

"On one hand, this migration toward treating lower-risk patients is a natural evolution given improved operator experience and comfort with the TAVI technique, and on the other, this trend could represent an over-confidence in the compelling outcomes of the procedure in a specific subset of patients that ignores possible downsides in treating a less sick patient population," Mills said. Data from randomized clinical trials will go a long way toward providing definitive clinical evidence, he added, "but clinicians are clearly already voicing their opinion in clinical practice."

In addition to Edwards and Medtronic, TAVI competitors include: Boston Scientific (Natick, Massachusetts) with its Lotus valve; St. Jude Medical (St. Paul, Minnesota) with its Portico valve; Colibri Heart Valve (Broomfield, Colorado); Loma Vista Medical (Burlingame, California); Direct Flow Medical (Santa Rosa, California) and Thubrikar Aortic Valve (Norristown, Pennsylvania) with its Optimum valve.

Earlier this month Boston Scientific initiated a post-market registry to assess real world performance of the Lotus valve (MDD, June 6, 2014). The RESPOND registry will collect data on clinical outcomes and device performance in 1,000 patients implanted at 50 centers around the world, the company reported. The system received CE mark approval last year (MDD, Oct. 29, 2013), but it is not available in the U.S.

Other hot topics discussed at the meeting, which Mills noted in his report, were TAVI device comparisons, paravlvular regurgitation, strokes, and procedural considerations.

The analyst's report pointed out that more than 95% of the 100,000-plus TAVI procedures performed worldwide have been with only two devices, Edwards' Sapien valve and Medtronic's CoreValve, the absence of large scale head-to-head randomized trials between the two platforms have led to ongoing, and sometimes heated, debates comparing the relative virtues of each device.

"The discourse reached a critical point following the presentation of CV high-risk data at ACC, with supporters of both camps digging in their heels and citing technological advantages, clinical results, and softer secondary endpoints to argue their positions," Mills said. While it may be tempting to compare results of the CV high-risk trial to Edwards' PARTNER IA study, he said such a comparison would be "ill advised" as they were different time frames, different patient populations, and different trial designs.

The issue of paravalvular leaks (PVL), or regurgitation, has been a hot-button TAVI topic since the first-generation platforms were born. But as next-generation technologies emerge, the issue is likely to be less of a concern. Most of the newer TAVI devices in development were designed to overcome limitations of the first-generation technology, which included the PVL problem.

While post-TAVR stroke rates had been declining thanks to improved case selection, procedure refinements, and increased operator experience, Mills noted that data from the CoreValve high-risk U.S. pivotal trial showed a reversal of that trend. However, he said, doctors at the meeting in Vancouver did not seem worried and had said if one looks hard enough they will eventually find evidence of a neurovascular event following a TAVR procedure.

Finally, the topic of which delivery approach should be taken during valve delivery has been another heated debate in TAVI discussions. Mills said percutaneous transfemoral (TF) delivery has become the preferred access method for TAVR, aided partially by the availability of new low-profile systems.

"The strong adoption of the TF approach is driven by the relative merits of this access route, which include lower mortality, improved quality of life, cost-effectiveness, ease-of-use, and the ability to perform the procedure without general anesthesia," Mills said. "Coupled with the strong trend to simplify TAVR procedures, our conversations with clinicians at TVT suggest TF approach may facilitate safe next-day discharge, which we think will become much more important to the TAVI adoption going forward; particularly as TAVR moves into treating lower-risk patients."

Published  June 16, 2014

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