From Ugly Duckling to Swan: 10 Years of TAVI

October 05, 2012

October 4, 2012 (London, United Kingdom) — The PCR London Valves meeting this week celebrated 10 years of transcatheter aortic-valve implantation (TAVI), with Dr Henning Rud Andersen (Aarhus University Hospital, Denmark)--the interventional cardiologist whose pioneering animal work laid the foundations for the technology--stating that Dr Alain Cribier (University of Rouen, France) had turned it "from an ugly ducking into a beautiful swan." Touchingly, Rud Anderson's elderly father received a TAVI device just last year.

In his keynote lecture, Dr Martin Leon (Columbia University, New York, NY) showed film footage of the first TAVI performed by Cribier and colleagues in April 2002 on a 57-year old man who Cribier acknowledged "would probably have been turned down for TAVI today." The patient presented in cardiogenic shock, with major left ventricular dysfunction (ejection fraction of 12%) and multiple comorbidities, which meant surgical aortic-valve replacement (SAVR) was contraindicated.

Their eyes wide with anticipation but at the same time full of anxiety, Cribier and his team waited to see what would happen following deployment of the valve. The procedure was a success, to their visible relief, and confirmed the feasibility of TAVI in humans. The patient unfortunately died four months later, but the foundation was laid for what is now recognized "as a breakthrough technology," said Leon.

What's in a name: TAVI or TAVR? No matter, technology is here to stay

Dr Martin Leon

Leon began with a lighthearted discussion about the different names given to the technology on either side of the Atlantic. He said he preferred transcatheter aortic-valve replacement (TAVR), the American abbreviation, to the European TAVI, mostly because it was easier to compare it with SAVR. And a TAVI "sounds like a child's toy," he joked.

Yet he also referred attendees to correspondence published in the Journal of the American College of Cardiology this summer [1], which argued that the abbreviation TAVR is confusing to patients, because the word "replacement" implies that the old valve is taken out, when in fact it is just displaced by the new one. Noting that TAVI seems to have been "somehow transformed" to TAVR between 2010 and 2011 in the US, the authors argue that TAVI "should be the acronym of choice."

But no matter the abbreviation used, Leon stressed that SAVR still remains the gold standard for most patients whose valve has failed and that "the major indication [for TAVI] will be high-risk aortic stenosis," ie, those who are deemed inoperable or at high risk from surgery.

TAVI should not be performed in patients at intermediate risk; trials are required for this. [But] I have a sense that these might be successful.

And although some have expressed concern about "risk creep"--whereby some centers in the world are thought to be performing TAVI on lower-risk patients--Leon said he believes this to be "modest' in most institutions. "TAVI should not be performed in patients at intermediate risk; trials are required for this," he stressed, noting that the two large studies addressing this patient population are now under way--SURTAVI and PARTNER IIa. And although results are some years away, "I have a sense that these might be successful," he mused.

But until then, "I expect to see dramatic continued growth of TAVI in the major indication of high-risk aortic stenosis," he said. More than 500 centers around the world have now performed TAVI on more than 50 000 patients. Germany remains the leader in this field, but the US "is now up and running" as the 43rd country in the world to have access to this technology, Leon noted, adding that his own institution has performed 350 TAVIs in the past 18 months.

I expect to see dramatic continued growth of TAVI in the major indication of high-risk aortic stenosis.

The US lags behind because--unlike Europe--regulations there stipulate that pivotal trials must be performed with TAVI devices before they are approved. The first on the market there was the Sapien transcatheter valve (Edwards Lifesciences) last year, for use in patients deemed inoperable by a multidisciplinary team based on the PARTNER B study. Expansion of the US license for Sapien to include high-risk aortic-stenosis patients who are also eligible for surgery is expected any day now, based on PARTNER A.

The PARTNER studies and other randomized controlled trials in the field--including the CoreValve (Medtronic) pivotal trial ongoing in the US--will provide rich data sets that will continue to provide insights into the technology for many years to come, Leon noted. For example, there will be 10 new reports on TAVI at the upcoming TCT 2013 alone, he said. "There is a dramatic explosion of new data becoming available that we'll be able to draw upon to help us understand some of the good and some of the bad."

There is a dramatic explosion of new data [on TAVI] becoming available that we'll be able to draw upon to help us understand some of the good and some of the bad.

To further improve interpretation of trials in this field, Leon notes that the Valve Academic Research Consortium (VARC) came up with specific definitions to aid in the reporting of clinical outcomes for patients undergoing TAVI, and these have now been refined further, representing the VARC 2 consensus document, which has just been published simultaneously in three journals [2].

There are also "spectacular" registries, including SOURCE 1 and 2 and XT, FRANCE 2, ADVANCE, GARY, and multiple country registries too numerous to mention "that will help us to understand many of the subtleties of clinical outcomes associated with TAVI," he noted. "And now we have the new TVT registry in the US, with follow-up that extends out to a year at least, including quality-of-life measures, with reimbursement linked to participation in this registry."

He observed, however, that reimbursement for TAVI is likely to be a sticking point in many markets, with economic constraints undoubtedly limiting the penetration of this new technology.

Will complications of TAVI turn out to be the Achilles heel?

Leon also cautioned that there remain "many unresolved" clinical issues with regard to TAVI. These include better characterization of the patients in whom TAVI would prove futile: "It's critical for us to make discriminatory decisions about whom we should not treat," he noted. And one of the major focuses in the future should be making sure TAVI recipients feel better, not just live longer, he noted.

In this regard, the complications of TAVI--such as stroke; paravalvular regurgitation, "the issue of the year"; vascular access issues; cardiac-rhythm disturbances requiring pacemaker implantation; and bleeding--may well turn out to be "the Achilles heel" of the procedure, he warned.

Also key is identifying the best access route for a particular patient, a topic that was much discussed at PCR London Valves. As well as the preferred transfemoral route of entry--although some surgeons argue against this assertion and numerous speakers said it is impossible to state that one route is better than another because there have been no head-to-head trials--there now exists the opportunity to perform TAVI transapically or via the transaortic, transsubclavian (also known as transaxillary), and even transcarotid routes.

The future of TAVR is bright, and I would argue that transradial [access] cannot be too far behind.

To help target the most appropriate patients for TAVI and decide on the best access route, as well as many other issues, a "new breed of multidisciplinary valve specialists able to communicate properly to patients what their options are" is needed, Leon said. Whether local or general anesthetic should be employed, the best device given the burgeoning number of new TAVI valves that are being investigated, not to mention newer delivery systems and cerebral embolic-protection devices, among other issues, are the types of decisions that will need to be made. Also vital will be a proper TAVI risk score, he said, noting progress with this in the form of the AKL score from the GARY registry.

"This has been a daunting field to summarize in a short period of time," he concluded. But he believes that "the future of TAVR is bright, and I would argue that transradial [access] cannot be too far behind," he told delegates.

Questions that patients ask

Meanwhile, during another session at the meeting, surgeon Dr Todd Dewey (Medical City Dallas Hospital, TX), outlined the "questions that patients always ask":

Dr Todd Dewey

  • Do I really need surgery, and what will it cost? "Aortic stenosis has a worse five-year prognosis than most cancers. We know that the clinical course is not good, including worsening HF symptoms and hospitalization. It's not a very pleasant way to go. So we can tell them that, without some sort of intervention--SAVR or TAVI/TAVR--their survival is going to be poor," Dewey said. Costs will vary, he noted, depending on the market and reimbursement policies.

  • What are my chances? Can I get through it and be functional? While there is no huge difference in survival between SAVR and TAVI/TAVR, the latter patients recover more quickly, he noted. "But the ones who are clearly operative patients, we will tell them, 'TAVI is not your best option.' They don't care if they die; they just don't want to be a vegetable." To this end, "patients are very interested in the stroke rate of the procedure they are considering," which stands at around 2.5% for SAVR and 5% for TAVR, he observed.

  • How long will the valve last? "There are now data showing good durability of transcatheter aortic valves out to about 2.5 or 3 years," and Edward Lifesciences has done equivalence testing showing the valves are likely durable for 15 years, which is "reasonable," Dewey said. "But we need more long-lasting data." He also speculates that as transcatheter valves are increasingly implanted into younger, more active patients, "We're likely to see a bit more degeneration."

  • How many have you done? "My favorite question. We know that repetition begets quality. You have to do a lot to get better at it," he stresses.

Leon is a nonpaid member of the scientific advisory board of Edwards Lifesciences and has received travel reimbursement from Edwards for activities related to his participation on the executive committee of the PARTNER trial.