麻豆传媒

PARIS -- Apical implantation of aortic valves may allow thicker, potentially more durable, leaflets, according to researchers presenting early results with one such novel device.

The novel Symetis Acurate transapical aortic valve has full-thickness porcine leaflets but requires only a small, 5-cm incision for minimally invasive implantation, Joerg Kempfert, MD, of the University of Leipzig Heart Center in Leipzig, Germany, and colleagues reported here at the European Society of Cardiology's EuroPCR meeting.

The first-in-man experience in 40 patients yielded 95% procedural success and a 12-month survival rate of 87.5%, which Kempfert called a good result for the high-risk group treated.

The valve represents a second generation beyond the transcatheter aortic valve implantation (TAVI) devices which are now on the market in Europe but are not yet FDA-approved. The Medtronic CoreValve uses a femoral or subclavian access route to the heart, while the Edwards Sapien valve can be implanted either transapically or transfemorally.

But valves that can be implanted transfemorally have to be crimped down to small diameters, typically 16 or 18 French, that can't accommodate full-thickness leaflets and so use reduced-thickness ones, Kempfert explained.

"If you use the transapical delivery route, then you are able to incorporate a fully porcine bioprosthesis within a nitinol stent," which takes a 28-French sheath system, Kempfert told reporters at a press conference.

A spokesperson for Edwards Lifesciences agreed that its valve leaflets for both transapical and transfemoral delivery routes are reduced thickness, but said other factors are more important, such as elasticity and homogeneity.

Currently, TAVI has an indication only in the typically older, more severe patients who are not candidates for surgical aortic valve replacement.

However, the treated population in Europe is already creeping toward lower risk groups.

Long-term durability remains an unknown with any of the percutaneous aortic valves, but is likely to become more of an issue in populations with longer life expectancy.

"It's way too early to compare [the novel] device to the market leaders," Kempfert cautioned at the press conference, adding that valve deterioration hasn't been seen so far in six years of experience with current valves.

In the study, one of the 40 cases attempted with the novel valve had to be converted to surgery and one had to be redone as a valve-in-valve with the Sapien valve.

Need for pacing after implantation has been an issue with TAVI, but the rate was only 5% in the study with the novel transapical valve, which Kempfert called acceptable.

Paravalvular leaks, another common concern with TAVI, were more than minor for only 3% of patients.

A critical point for the elderly population treated (mean age 82.2) was that 90% showed improvement in clinical status.

One unique feature, Kempfert noted, was that the valve implantation technique used anatomical rotation to align the replacement to match the native aortic valve.

Another is that the delivery system provides tactile feedback. "That way, you get the option to really intuitively position the valve until it's smoothly anchored down into the aortic annulus," he explained at a press conference.

Session co-chair Alain G. Cribier, MD, of University Hospital Charles Nicolle in Rouen, France, agreed that the novel valve "has a number of advantages" but was skeptical of the need to align the valve commissures.

Whether precise positioning really matters in terms of coronary impingement, for example, hasn't been proven, but it can't hurt, he noted at the session.

The novel valve will soon be submitted for European regulatory approval, Kempfert noted, but is also being developed in a transfemoral version that may target a different patient population.

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