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PARIS -- For people with failed surgical aortic valves, the choice of device for a subsequent valve-in-valve transcatheter aortic valve replacement (TAVR) had implications for valve hemodynamics down the line, researchers showed in the LYTEN randomized trial.

Between newer-generation balloon-expandable Sapien versus self-expanding Evolut bioprostheses, there were significant differences in valve gradients by Doppler echocardiography at 30 days following valve-in-valve TAVR:

• Maximal transvalvular gradients: 40 vs 28 mm Hg (P<0.001)

• Median transvalvular gradients: 23 vs 15 mm Hg (P<0.001)

• Proportion of cases with residual transvalvular gradients >20 mm Hg: 62% vs 21% (P<0.01)

Besides the improved valve hemodynamics, the Evolut line also trended toward less severe prosthesis-patient mismatch (PPM) according to both VARC-2 (44% vs 64%) and VARC-3 definitions (20% vs 39%).

Meanwhile, moderate-severe aortic regurgitation also favored the Evolut device without reaching statistical significance, according to the presentation at the EuroPCR meeting by Josep Rodés-Cabau, MD, PhD, an interventional cardiologist at Quebec Heart & Lung Institute of Laval University in Quebec City.

A manuscript was simultaneously published in the .

Notably, for both valve types in LYTEN, clinical outcomes at 30 days were marked by zero deaths, strokes, or permanent pacemaker implants. The Sapien group counted one major bleed and one major vascular complication, whereas Evolut was associated with one case of myocardial infarction.

Valve-in-valve TAVR is becoming an important topic in the field since the TAVR expanded to younger, low-risk patients, for whom one valve procedure may not be sufficient to last the rest of their lifetimes.

There are data suggesting short-term advantages to valve-in-valve TAVR instead of surgery for people with a failing bioprosthesis. At most centers, the first attempt is likely TAVR for a patient age 70 years, but this should of course be subject to individualized decision-making, according to session panelist Sabine Bleiziffer, MD, PhD, a cardiac surgeon at German Heart Center in Munich.

In small anatomies, however, and given the high PPM in LYTEN, surgery should still be seriously considered, said cardiac surgeon Olaf Wendler, MD, PhD, of Cleveland Clinic London.

Bleiziffer's suggestion for a randomized trial comparing surgery and valve-in-valve TAVR in a low-risk population was countered by Rodés-Cabau's point that such a trial would be difficult given the low event rates that can be expected.

LYTEN participants were 102 patients averaging 80 years of age, with approximately half being men.

Conducted at 11 established TAVR centers in Canada, Europe, and the U.S., the trial had people with small (inner diameter ≤21 mm) stented surgical valves randomized to valve-in-valve TAVR using one of the two study devices.

People in the balloon-expandable TAVR group received a 20-23 mm Sapien 3 (n=40) or Ultra device (n=6). Self-expandable TAVR was performed using 23-26 mm Evolut R (n=20), PRO (n=31), and PRO+ (n=1) devices.

The two groups were fairly well balanced, though there were trends of the Sapien group being more likely male, and presenting with higher Society of Thoracic Surgeons scores at baseline. These patients were also more likely to undergo surgical ring fracture for their valve-in-valve TAVR.

For the overall cohort, Rodés-Cabau reported that the main mechanism of surgical bioprosthesis failure was stenosis in two-thirds, and regurgitation in the rest.

Importantly, starting around halfway through the study, operators adopted invasive hemodynamic measurements the day after TAVR.

This revealed lower transvalvular gradients compared with echocardiographic measurement -- resulting in similar gradients between balloon- and self-expandable valve types (15 mm Hg vs 12 mm Hg, P=0.41).

Such discordance may be attributed to differences in the exact anatomy at which echocardiographic and invasive measurements are taken -- given the slower blood flow between the aortic valve and the ascending aorta -- as well as limitations of the Bernoulli equation, the investigators suggested.

The discord between invasive and noninvasive hemodynamics appeared more pronounced for the Sapien group.

During the EuroPCR session, interventional cardiologist Azeem Latib, MD, of Montefiore Health System in New York City, called the trial "one of the most important studies being presented" at the conference.

Nevertheless, he suggested that in people with small anatomies, the Doppler velocity index (DVI) may be a better way to gauge valve performance.

Rodés-Cabau agreed that "gradients can be misleading" and said his group's DVI analysis is pending.

Other limitations include the study's small sample and the potential bias arising from the surgical ring fracture difference between groups.

Longer follow-up will be needed to evaluate the impact of valve hemodynamic differences on clinical outcomes after valve-in-valve TAVR, according to Rodés-Cabau.

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