Transcatheter Mitral Valve-in-Valve a ‘Good Option’, but With Higher Gradients

For patients with failing bioprosthetic surgical mitral valves, the transcatheter mitral valve-in-valve (ViV) procedure provides early outcomes similar to those seen with repeat surgical replacement, albeit with higher postprocedural gradients, data from a single high-volume center suggest.

Estimated 1-year survival was not significantly different between the two groups at roughly 90% after ViV and 80% after redo surgery (P = 0.33), Alexander Brescia, MD (University of Michigan, Ann Arbor), reported recently during the virtual Society of Thoracic Surgeons 2022 meeting.

The average postprocedural mitral valve gradient, however, was higher after the transcatheter procedure (8.9 vs 5.7 mm Hg; P < 0.001), particularly when smaller valves were implanted.

“Transcatheter mitral valve-in-valve is a new tool to treat prosthetic failure which confers a trade-off between lower morbidity but higher valve gradients,” Brescia said, noting that the long-term durability of using an upside-down TAVI valve in the mitral position—as was done in these cases—is unknown.

Addressing the higher gradients seen after ViV, Brescia said “surgeons should make every effort to implant larger valves at the index operation to best prepare for maximizing valve size at future interventions,” and he added that “developing purpose-built transcatheter mitral prostheses may help achieve better hemodynamics with low morbidity in transcatheter mitral valve-in-valve procedures.”

Though transcatheter mitral ViV has emerged as an alternative to repeat surgery, experience is limited, Brescia said. A series from the Mayo Clinic showed that ViV procedures were associated with better survival at 30 days—a finding that also came out of a recent systematic review—but worse survival at 5 years, compared with redo surgery. And Italian researchers reported that either transcatheter mitral ViV performed with either transapical or transseptal access provided results similar to those seen with redo surgical replacement.

The current study explores outcomes of the transcatheter and surgical procedures performed at a high-volume mitral center, focusing on the 48 patients treated with ViV and 36 treated with redo surgery between 2016 and 2020. Mean age was higher in the ViV versus surgery group (65 vs 58 years). Women made up 63% and 72%, respectively, of the two groups. Average LVEF was about 60% overall. Surgical risk according to the STS score (mean 7.9% and 7.1%) and the EuroSCORE II (mean 11.4% and 11.7%) did not significantly differ between the patients undergoing ViV and surgery.

For ViV, most of the procedures were performed with transfemoral/transseptal access, and the rest were transapical. The median size of the original surgical valve was the same in both groups (27 mm), with a slightly smaller implanted valve size with ViV versus redo surgical procedures (26 vs 27 mm; P = 0.022).

Before the procedure, mean mitral valve gradient was numerically higher in the patients slated for ViV (12.5 vs 11.3 mm Hg; P = 0.32), with a significant gap opening after the procedure. Gradients were highest after ViV when smaller TAVI valves were implanted—14.3 mm Hg with 23-mm valves, 8.8 mm Hg with 26-mm valves, and 8.3 mm Hg with 29-mm valves.

Brescia noted that in the few patients who received a 23-mm valve, the original surgical bioprostheses—a 25-mm Mosaics (Medtronic)—were “quite small.”

The size of the failing surgical valve does factor into decision-making around the next procedure, Brescia said. “For us, patients who are at low-to-intermediate risk who have a small valve, might have a [25-mm] Mosaic, we would prefer to do surgery on that patient. Patients with large valves at . . . high risk would lend more towards valve-in-valve,” he said. For patients in the gray area—those with small valves initially and an extremely high surgical risk, for instance—“I think you either offer the valve-in-valve with the understanding that this is their only shot or you do medical management and don’t offer a valve-in-valve.”

S. Chris Malaisrie, MD (Northwestern Medicine, Chicago, IL), one of the moderators of the session at which Brescia reported the results, noted that transcatheter mitral ViV using the Sapien 3 (Edwards Lifesciences) transcatheter valve designed for TAVI is approved by the US Food and Drug Administration for high-risk and inoperable patients. He’s one of the leaders of the PARTNER 3 Mitral Valve-in-Valve trial testing the approach in intermediate-risk patients, with 1-year results expected sometime this year.

Malaisrie told TCTMD that the experience with mitral ViV at his center is similar to what Brescia reported at his center. “It is at least a good option for high-risk patients, for which it’s FDA-approved, and may be a good option for patients who are intermediate risk,” he said. In the latter group, he added, “we have to be very sure that we’re going to be able to put a large enough valve in during a mitral valve-in-valve procedure.”

It’s too early to say whether there’s a difference in survival between mitral ViV and redo surgery, Malaisrie commented, pointing to the higher gradients seen after the transcatheter procedure: “It’s an Achilles’ heel of doing any valve-in-valve procedure. You’re limited by the size of the previous surgical valve.” Ultimately, he said about ViV, “there’s probably some benefit short term in terms of safety, but long term may not be as good as repeat surgery.”

For the initial surgical management of these patients, it’s important for surgeons to think about the possible need for additional interventions—including transcatheter ViV—in the future and to put in a large enough surgical prosthesis to give patients options, Malaisrie indicated.

If the gradient is still high after a transcatheter mitral ViV procedure, fracturing the surgical valve—an off-label but accepted procedure—is an option to lower it, he pointed out. “The proceduralist should know that gradients are a possibility and if they do the initial mitral valve-in-valve and there is a gradient, they may consider doing a valve fracture at the time of mitral valve-in-valve.”