Break to Fix? Purposely Fracturing Failed Surgical Valves May Help Transcatheter ViV Delivery

Intentionally using a high-pressure balloon to fracture failed bioprosthetic valves, either before or after TAVR device implantation, may prove to be a solution to patient-prosthesis mismatch (PPM) that can occur in conjunction with valve-in-valve (ViV) therapy. Early clinical findings on this technique—which researchers say holds potential but is still in its early stages—were published online last week in Circulation: Cardiovascular Interventions.

While many people may find the idea of bioprosthetic valve fracture (BVF) counterintuitive, “it is gaining traction,” lead author Adnan K. Chhatriwalla, MD (Saint Luke’s Mid America Heart Institute, Kansas City, MO), told TCTMD. Research is not only occurring in the United States, he said, but also in Europe.

Nine hospitals participated in the study, but one-third of the 20 cases in the current series were done at Saint Luke’s Mid America Heart Institute, with the other sites contributing just one or two patients, Chhatriwalla said. “So we’re going to need to collaborate across the country with other centers to try to pool our data together and better understand how to best to this, what the benefits are to patients, what the potential complications are.”

No Procedural Complications, but One Stroke

In their paper, Chhatriwalla and colleagues report that TAVR was performed using a mix of both balloon-expandable and self-expanding valves, and the original bioprosthetic valves in question included Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic.

In 75% of the cases, bioprosthetic valve fracture was done following transcatheter ViV placement and in 25% prior to TAVR.

“Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap,” they explain.

With BVF, transvalvular gradient decreased (from 20.5 ± 7.4 to 6.7 ± 3.7 mm Hg), while valve effective orifice area increased (from 1.0 ± 0.4 to 1.8 ± 0.6 cm2; P < 0.001 for both). There were no procedural complications reported, though one patient had “new left-sided weakness on postprocedural day 1 and was found to have a right posterior frontoparietal stroke in the area of a posterior branch of the middle cerebral artery, without acute hemorrhage or mass effect, from which he fully recovered,” the researchers report.

Asked about this event, Chhatriwalla said it is impossible to know at this point if the stroke occurred in relation to the TAVR procedure itself or was related to the high-pressure inflation during BVF.

Broken Promise

Despite the potential role for BVF, Chhatriwalla stressed the many unknowns. Chief among them, he told TCTMD, is whether these immediate hemodynamic changes will last and if they will translate into better long-term survival.

Data from the Valve-in-Valve International Data (VIVID) registry, however, underscore the importance of having a larger orifice area for the second valve. Not only was the incidence of severe PPM after ViV TAVR higher in patients with smaller surgical valves, but at 1 year, survival was worse in patients whose bioprosthetic valves had a labeled size of small (≤ 21 mm) or intermediate (> 21 mm to < 25 mm) versus large (≥ 25 mm). “We think that has everything to do with the hemodynamic result that you get. If you start with a small valve and then you put a smaller valve in that valve, you end up with a problem,” Chhatriwalla noted.

If you start with a small valve and then you put a smaller valve in that valve, you end up with a problem. Adnan K. Chhatriwalla

In terms of complications, Chhatriwalla said concerns have been raised about injuring the aorta or rupturing the annulus, though so far these have not been seen. It’s also possible that BVF might increase the risk of thromboembolic events, though it might be hard to tease out the mechanism by which they occur, he said.

But there are ways to mitigate risks, Chhatriwalla stressed, such as by timing BVF differently.

Some operators favor doing BVF ahead of TAVR, he said. The thought behind this is that the size of the new TAVR valve is selected with the knowledge of whether or not the bioprosthetic valve can be fractured in the first place. “So you fracture the valve first, you have success, and then put in maybe a larger-sized [TAVR] valve as a result,” he explained.

But he and others at Saint Luke’s prefer doing it after the TAVR device is implanted, Chhatriwalla added. “Our mindset [is] we’re going to put in the valve size that’s warranted, and we’re going to check the hemodynamics. Then if the hemodynamics are fine, we’re okay, we don’t need to fracture this [bioprosthetic] valve. We’ll leave it as is. But if we’re not happy with it, that’s when we’re going to do the valve fracture after the fact.”

There are potential safety advantages to the post-TAVR tactic, he said. “You could argue if the new valve goes in and you kind of push the old valve leaflets away and you’ve created a seal there, that maybe even if you do the high-pressure inflation at that point, you’re going to have less risk of embolism. That’s a theoretical thing.” This approach might also enable better valve expansion and, hopefully, better hemodynamic results, Chhatriwalla suggested.

On the flip side, there’s the possibility that doing a high-pressure inflation inside the new TAVR valve could have implications for long-term durability. “Maybe there could be a little bit of injury to those valve leaflets that you don’t see initially” but that has lasting effects, he said.

As of yet it is unclear which balloon size or degree of inflation pressure is best. Most cases in this series were done with balloons sized 1 mm larger than the labeled valve size.

The Need for BVF

In an accompanying editorial, Doff B. McElhinney, MD (Stanford University, Palo Alto, CA), also highlights many unknowns while being optimistic about the future.

“Now that the feasibility of intentional [bioprosthetic valve] frame fracture has been established not just in case reports, but in this small series, we can move on to understanding the nuances of the procedure, as well as longer-term outcomes related to hemodynamics and valve-in-valve function,” he says. “We look forward to learning more, both in terms of follow-up of the current cohort and through the experience of others.”

Though an exact number is hard to come by, Chhatriwalla guessed that there are thousands of ViV procedures done in the United States per year. “As the patients who’ve had surgical valves, as those valves [and] patients get older, you’re going to have more and more surgical valve failure,” he said.

“On the other hand, surgeons are also aware that putting in small valves surgically is not a great idea, so they’ve been changing their behavior hopefully and putting in larger valves,” Chhatriwalla continued. Moreover, device companies are increasingly making lower-profile devices, “so that the internal diameter of the valve is not so much different from the external diameter,” he said.

Even this doesn’t close the door on BVF, however, since it’s possible that fracturing could prove useful for optimizing results even in larger bioprosthetic valves, Chhatriwalla suggested.