Trade-offs Between Self-Expanding and Balloon-Expandable Valves in Very Large Annuli
Getting a good seal is the chief concern, and while cases are uncommon now, experts expect more as TAVR moves into younger, lower-risk patients.
CHICAGO, IL—For a patient with a large aortic annulus undergoing transcatheter aortic valve replacement, a new study suggests there are different risks and benefits when it comes to the use of self-expanding and balloon-expandable transcatheter valves.
Treatment with the self-expanding CoreValve or Evolut R (Medtronic) is associated with a larger risk of postprocedure left bundle branch block and more frequent need for a new permanent pacemaker when compared with the Sapien 3 balloon-expandable valve (Edwards Lifesciences), but use of the Evolut R is associated with better valve hemodynamics and a lower mean gradient.
“Both devices were equally safe, but the bottom line is that it comes down to what the site is comfortable using,” lead investigator Gilbert Tang, MD (Icahn School of Medicine at Mount Sinai, New York, NY), told TCTMD. “I think both valves perform equally well—Sapien 3 and Evolut R—with the caveat being [that] at least in our study the Evolut R had higher incidence of new persistent left bundle branch block and new pacemaker implantation.”
Speaking at the 2018 Structural Heart Disease Summit, Tang said the clinical presentation of patients with very large annuli is not too common, noting their analysis included just 176 patients treated at two hospitals. He suspects, however, that physicians might start to encounter these patients more often.
“As you get into larger annuli, the issue is whether the balloon-expandable or self-expandable valves seal adequately,” he said. “Certainly, with TAVR expanding to younger, lower-risk patients, these individuals may have annuli larger in size than the current population, which is mostly intermediate-, high-, and extreme-risk patients. I think we’re going to see more of these patients in practice in the future.”
While Sapien 3 relies on balloon expansion to provide radial force against the annulus and the leaflets, and helps to seal and anchor the valve in place, CoreValve and Evolut R are comprised of a self-expanding nitinol frame that relies on passive radial force to seal the annulus and leaflets. Although operators can postdilate and expand CoreValve and Evolut R, the valves tend to recoil to some extent given its nitinol frame, said Tang.
Philippe Généreux, MD (Morristown Medical Center, NJ), who moderated the session, said the study results are comparable with what others observe in clinical practice. With very large annuli, those with a mean annular area of 700 to 800 mm2, “we’re limited by the self-expanding valve because of the nitinol frame design,” he said. “If you postdilate, it’s going to come back, whereas the Sapien 3 you can stretch and it will be more accommodating.”
Trade-off Between Transcatheter Valves
In the present series of 176 patients, the mean annular area, the mean annular diameter, and mean annular perimeter was 606.8 mm2, 28.0 mm, and 88.1 mm, respectively. These dimensions, as well as the mean, minimum, and maximum annular diameter, were higher among patients treated with the 29-mm Sapien 3 device.
Additionally, the average annulus dimensions for the left ventricular outflow tract were larger among those treated with Sapien 3, as was the sinotubular junction. This “makes sense because with a balloon-expandable valve, if the sinotubular junction is small, we could risk injury with the balloon-expandable platform,” said Tang. From a clinical perspective, patients treated with Evolut R had a higher incidence of peripheral artery disease, which also aligns with clinical practice given that the system has a lower delivery profile and is typically selected for such patients, he said.
Regarding outcomes, more than 38% of patients treated with CoreValve or Evolut R had new left bundle branch block after TAVR and approximately one-third of patients required a new pacemaker. In contrast, just 9.0% of patients treated with Sapien 3 had left bundle branch block after TAVR and only 8.6% required a new permanent pacemaker.
The in-hospital mean valve gradient was 10.6 mm Hg in patients treated with Sapien 3 and 7.6 mm Hg among those who received Evolut R, a difference that was statistically significant. At 30 days, the mean gradient remained significantly lower with Evolut R compared to Sapien 3. There was no difference in the rate of mild (or greater) paravalvular leak between the valves at 30 days, although Sapien 3 was associated with less mild (or greater) paravalvular leak in-hospital when compared with the CoreValve- and Evolut R-treated patients.
“Certainly, there’s a trade-off,” said Tang. “I think that’s what the message would be. Statistically, there is a higher incidence of left bundle branch block and the need for a permanent pacemaker with the 34-mm Evolut R over Sapien 3. Hemodynamically, however, the 34-mm Evolut R certainly performs better than the 29-mm Sapien 3. But we’re talking about an average [pressure] gradient of 3-4 mm, so clinically it’s probably not that significant.”
Regarding the conduction disturbances with self-expanding valves, Tang noted that the implanted 31-mm and 34-mm CoreValve and Evolut R valves were more oversized by the annular area and perimeter based on instructions for use. This greater degree of oversizing versus Sapien 3 was associated with a higher risk of left bundle branch block and pacemaker implantation, he said.
During the session, Généreux said there is a bias toward the self-expanding valve when the anatomy is particularly “nasty,” when there is heavy calcification, or when there is a potential for aortic root rupture. Tang echoed those thoughts, noting that patient comorbidities, age, and other factors factor in to the decision. “It’s not just anatomy alone,” said Tang.
Photo Credits: Medtronic and Edwards Lifesciences
Tang GH. TAVR with the largest balloon-expandable vs self-expanding valve in very large annuli: a multicenter study. Presented at: Structural Heart Disease Summit. June 21, 2018. Chicago, IL
- Tang reports no relevant conflicts of interest.