The Next Frontier: Repositionable, Retrievable Transcatheter Valves Show Promise in Noncalcific Aortic Regurgitation


As transcatheter valve technology transitions from its original intended use in calcified aortic stenosis to potentially treating patients with noncalcific aortic regurgitation, several new devices featuring repositionable designs, anchoring abilities, and self-positioning geometry are showing promise.

The Next Frontier

“Most people are really pretty positive and anxiously awaiting the data on these valves because we think they are indeed the next step,” said Peter C. Block, MD, of Emory University Hospital (Atlanta, GA). “But remember, we have huge experience with our first-generation valves… and they are not going to go away in a hurry to be replaced entirely by these new-generation valves. There's no question about that.”

A Repositionable Advantage?

In the first of 2 papers published online, November 18, 2015, ahead of print in JACC: Cardiovascular Interventions, Joachim Schofer, MD, PhD, of Albertinen-Heart Center (Hamburg, Germany), and colleagues describe their experience with transfemoral implantation of the Direct Flow Medical transcatheter heart valve in 11 high-risk patients (mean age 74.7 years; 63.6% women) with severe noncalcific pure aortic regurgitation at 6 European centers between May 2015 and April 2015.  

This particular valve is nonmetallic, made of bovine pericardial tissue leaflets, and can be implanted via a transfemoral, subclavian, or direct aortic approach. It uses a “formed in place support structure” with 2 independently inflated rings to ensure anchoring of the device, according to the authors.

Device success, the study’s primary endpoint, was 100%, with one patient requiring device retrieval after being pulled through the native annulus into the ascending aorta; a second device was successfully implanted. One patient experienced mild paravalvular regurgitation, with the rest reporting trivial amounts or none. There were no cases of coronary obstruction, intra-procedural valve embolization, or vascular complications. Mean procedural time and contrast volume used were 74.8 minutes and 95.8 mL, respectively.

One patient required conversion to surgery likely due to insufficient oversizing, and 1 died of pneumonia and acute respiratory failure. There were no cerebrovascular events, and 1 patient underwent cardiac resynchronization therapy to treat severely depressed LV function. Overall, all patients saw their symptoms improve following the procedure with 72% in NYHA class I or II at the end of the study (compared with 18% at the study outset).

All patients were evaluated with a multidisciplinary heart team and multimodality cardiovascular imaging before being enrolled in the study. Mean STS score and logistic Euroscore were 8.84 and 19.9%, respectively, at baseline.

While the study “confirms feasibility” of this procedure, “it also highlights the challenges of treating this subset of patients by transcatheter implantation of aortic prostheses that were designed for implantation in calcific aortic valves and the importance of sufficient oversizing to anchor the valve in the noncalcified aortic annulus,” Schofer and colleagues write.

The valve’s “unique design… offers some theoretical advantages” for treating patients with pure aortic regurgitation, they say, including:  

  • Full functionability during positioning, which improves hemodynamic stability
  • Repositionability to fine-tune the final result and decrease residual aortic regurgitation
  • Full retrievability if the position is unstable or if there is significant residual aortic regurgitation

Two-Piece, Two-Stage Valve

The second paper, by Chunsheng Want, MD, of Shanghai Cardiovascular Institution and Zhongshan Hospital (Shanghai, China), and colleagues, followed 6 high-risk patients (mean age 75.5 years; 66.7% men) with noncalcific, native aortic regurgitation who received the J-Valve (JieCheng Medical Technology) between May and December 2014. Mean logistic Euroscore was 29.32% and all patients had NYHA class III or IV heart failure at baseline.

This two-piece, self-expandable porcine valve has a three-prong clasper and a support frame designed to be implanted in 2 stages—the clasper is deployed in the aortic root and then the prosthesis is placed into the aortic annulus without rapid pacing. All patients were treated transapically and received transesophageal echocardiography to assist with implantation.

No pre or post-dilatation was performed and no patients were converted to surgery. Also, there were no coronary obstructions or valve malpositioning. Mean contrast dose was 86.33 mL and mean procedure time was 101.67 minutes.

Appropriate prosthesis size was deemed to be 5-10% larger than the native annulus diameter—the devices used in this study were half 25mm and half 27mm. No cases had significant paravalvular leak and the mean transvalvular gradient was 6 mmHg.

All patients survived to 30 days with no post-operative complications—all patients were in NYHA class I or II. Three patients had new-onset left bundle branch block and one patient had first-degree atrioventricular block without bradycardia. One patient had new-onset A-fib but did not need a permanent pacemaker, and one patient had stage 1 acute kidney injury.

Here as well, authors stressed the importance of good annulus sizing, especially because the largest size available for the J-valve is 27 mm, and the risk of paravalvular leak and valve dislodgement increase with improper sizing. A 29-mm prosthesis is in development, they report, as are transaortic and transfemoral platforms. “With these new approaches, the implantation might be less traumatic,” they write.

Many Options, Little Data

“These are interesting papers that begin to explore the possibilities of ultimately where we might go with transcatheter valve replacement,” Block told TCTMD, adding that the question remains as to the limits of the technology. Both papers, he said, begin to explore this issue and are “actually relatively positive in that respect.”

Feasibility has now been established, Block added, which should help alleviate some of the reluctance felt by those hesitant to use either the CoreValve (Medtronic) or Sapien (Edwards) devices off-label for patients with noncalcific regurgitation. “I know for a fact [that these valves have been used off-label], but … these valves were not designed for anything but calcified aortic stenosis,” he said.

In an editorial accompanying both studies, John Webb, MD, and Nay Htun, MD, both of St. Paul’s Hospital (Vancouver, Canada), discuss both the Direct Flow and J-Valve devices as well as a host of others. Several registries “document feasibility [of the CoreValve] in patients with pure aortic regurgitation,” they note, and although they show outcomes that are “less desirable than reported with aortic stenosis, [this device] may represent a useful alternative when surgery is not an option.”

Additionally, the Evolut R (Medtronic), a partially recapturable and repositionable valve, “represents an attractive advance,” Webb and Htun write. But the Direct Flow and the Lotus (Boston Scientific) valves—which can both be fully repositioned or removed—are perhaps more promising in this population, but with limited data so far.

With its narrow waist and extended frame, the Acurate valve (Symetis SA), should facilitate optimal positioning, although it has only been tested in 8 patients. Lastly, devices that work by “incorporating design elements that utilize the leaflets of the native valve to assist in [prosthesis] positioning and fixation,” such as the Engager (Medtronic), JenaValve (JenaValve Technology), and J-Valve, also show potential, they write.

The “ideal valve,” Webb and Htun conclude, will involve minimally invasive implantation, reliable positioning or repositioning, an effective seal, a range of sizes, durability, and a fixation mechanism that constrains—not dilates—the aortic annulus.

Block said that recapturability is the most exciting development among the new devices. “If there is significant aortic paravalvular leak, for example, or the valve for one reason or another slides or moves and is not in a favorable position, [then] it can be recaptured: that’s a huge advantage,” he said, Even though these complications seldom occur, “the ability to recapture makes these new-generation valves very favorable.”

Importantly, the valves in the studies “seem to be repositionable without sacrificing anything in terms of aortic valve gradient and ability to place them properly,” Block added.

But more information is needed. Both the Direct Flow and Lotus valves are currently being compared with CoreValve in US trials and continued safety and efficacy studies are ongoing, Block said. “We need to learn more about these new valves…. Once those data are available, it will be much easier to gauge how these valves should or can be used,” he observed. 


Source:
1. Schofer J, Nietlispach F, Bijuklic K, et al. Transfemoral implantation of a fully repositionable and retrievable transcatheter valve for non-calcified pure aortic regurgitation. J Am Coll Cardiol Intv. 2015; Epub ahead of print. 
2. Wei L, Liu H, Zhu L, et al. A new transcatheter aortic valve replacement system for predominant aortic regurgitation implantation of J-Valve and early outcome. J Am Coll Cardiol Intv. 2015; Epub ahead of print. 
3. Webb J, Htun N. Transcatheter options for the treatment of non-calcified aortic regurgitation [editorial]. J Am Coll Cardiol Intv. 2015; Epub ahead of print.

Disclosures:

  • Schofer and Wang report no relevant conflicts of interest.
  • Webb reports serving as a consultant to Abbott Medical, Edwards Lifesciences, and St. Jude Medical.
  • Block reports holding equity in Direct Flow Medical.

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