Better Durability With Self-Expanding TAVI? Clues From UK TAVI

PARIS, France—Updated data from the UK TAVI registry tracking long-term valve function hints that severe structural valve degeneration (SVD) affected nearly 6% of patients who received an early generation TAVI device. Also, severe deterioration appears to be more common with balloon-expandable than with self-expanding devices.

Noman Ali, BMBS, PhD (Leeds Teaching Hospitals NHS Trust, England), who presented the data here at EuroPCR 2022, acknowledged to TCTMD the pitfalls of the observational data and any comparisons drawn between devices.

“Obviously there are limitations given that they are first-generation valves, but the fundamental differences between the Sapien and the CoreValve haven't changed in terms of one being supra-annular [and] one being intra-annular, one being balloon-expandable and one being self-expanding,” Ali told TCTMD. “Those differences are still present in the current iterations. There have been some improvements, but I think the fundamental message is that the supra-annular design appears to lend itself to a slower rate of degeneration, and I think that will still be seen in newer valves. The overall numbers might be lower in both, but I suspect that difference might still be present.”

A previous snapshot from UK TAVI, of just 149 patients followed for a median of 5.8 years, pointed to a slightly higher incidence of moderate SVD, with roughly half of the cases due to new aortic regurgitation and 43% to restenosis.

In this latest data with longer follow-up, however, investigators focused on severe SVD and zeroed in on differences between valve types among 221 adults who underwent TAVI at one of 11 centers in the United Kingdom between 2007 and 2011. All patients had undergone echocardiograms postprocedure and again at a time point beyond 5 years, allowing for assessment of SVD.

Valve Durability Insights

Investigators for UK TAVI used a definition of severe SVD adapted from the European task force committee guidelines. These specify at least one of the following: mean gradient of ≥ 40 mmHg and/or ≥ 20 mmHg increase from baseline; a peak velocity ≥ 4 m/s and/or ≥ 2 m/s increase from baseline; or severe new or worsening intraprosthetic aortic regurgitation.

Median follow-up presented here today was 7.0 years (ranging from 5 to 13 years), with 43 patients being more than 10 years post-TAVI. Just over two-thirds of patients (mean age 79) had been treated with the CoreValve (Medtronic), while 31.3% had received a Sapien/Sapien XT valve (Edwards Lifesciences). Transfemoral access was used in 79%, and valve deployment was successful in 97.2% of patients.

Over the extended follow-up period, 13 patients (5.9%) developed severe SVD a median of 7.8 years post-TAVI. In three cases, SVD was due to aortic regurgitation, and in 10 the underlying cause was stenosis. Hemodynamic function of the valve remained stable for most patients and in some cases actually improved with time. Analyzed by valve type, however, a higher proportion of patients treated with the balloon-expandable valve versus those treated with the self-expanding valve developed severe SVD (11.9% vs 3.5%, P = 0.02).

Speaking with TCTMD, Ali said he hopes these data can help inform lifetime management considerations for patients.

“We know that we're going to be using TAVIs in younger and younger patients going forward, and this just adds another variable to the decision-making process,” he said. “You've got to consider the possibility of TAVI-in-TAVI, which perhaps favors a balloon-expandable valve to begin with, followed by a self-expanding valve. Then you've got to balance that with the prospect that that may degenerate faster.”

On the other hand, for a slightly older patient, you might consider a self-expanding valve to begin with, since its longevity may more closely match that of the patient.

“I think the take home is just integrating this information into the overall decision-making process for lifetime management of these patients, and I think we need to move, as heart teams, from just looking at what's the best valve for this patient now to thinking about what's going to be the next valve beyond this,” he said. “When TAVI first came out, we were looking basically out to 5 years because patients were 85 years old. Now when they're 70 years old, we have to be thinking 15, 20 years down the line, and I think this data can be used as part of that decision-making process.”

We need to move, as heart teams, from just looking at what's the best valve for this patient now to thinking about what's going to be the next valve beyond this. Noman Ali

Commenting on the data for TCTMD, session moderator Jonathan Schwartz, MD (Sanger Heart & Vascular Institute, Charlotte, NC), noted that the UK TAVI numbers represent the largest data set for post-TAVR patients at or beyond 10 years.

“It's hard to extrapolate too much from it as there were only 43 patients in that cohort, but as mentioned, it's the best we have to date,” said Schwartz.

This analysis, he pointed out, focused exclusively on leaflet durability related to regurgitation and stenosis, but other factors likely also play a role in SVD, including endocarditis, paravalvular leak, commissural alignment, proper valve expansion, supra-annular versus intra-annular design, and associated postprocedure gradients.

Ongoing questions around hypoattenuated leaflet thrombosis and mobility, and how those may influence valve durability, remain unanswered, he said. In the UK TAVI patients, “how much of this is true leaflet deterioration? We know younger, active patients, and end-stage renal disease patients on hemodialysis show leaflet deterioration at a significantly accelerated rate than older, sedentary, nondialysis patients.”

Another consideration is leaflet material, Schwartz continued, noting that some devices use bovine pericardium and others porcine. “This has changed little from the earlier-generation valves,” he said, although polymer-derived leaflet platforms are an area of active investigation.

“Time will tell where valve innovation heads from here, with significant improvements made since the time of the bioprostheses used in this study. While current TAVR platforms have evolved greatly since the those presented in this trial, this is an enlightening first look into the long-term outcomes for TAVR patients, and newer valves likely will only show even better results,” said Schwartz.

Correction: This story has been corrected to address an error in an earlier headline, which misidentified balloon-expandable devices as having better durability in this analysis.