Next-generation TAVR system approved to treat patients with severe aortic stenosis

Gilbert H.L. Tang, MD, MSc, MBA

The Navitor system has been around in Europe for some time. It offers something different from the current platforms in the U.S.

There are two market leaders in the U.S. One is the Sapien 3 Ultra platform (Edwards Lifesciences), a balloon-expandable device, which is intra-annular, meaning when the device is deployed, the leaflets are at the annular level, where the valve is attached. It relies on a balloon to deploy. The other is the Evolut platform (Medtronic), which has a nitinol stent frame that unwinds the catheter to expand and deploy the valve. Unlike the Sapien system, this is a supra-annular platform, which means the leaflets are mounted above the annulus of the frame, so that when it is deployed, the leaflets sit above the annulus. Because of that, the gradients have been reported to be lower than with the Sapien platform. In addition, the valve frame has an hourglass shape to give better hemodynamics.

The Navitor platform is kind of a mix of the two. It has a taller frame and is a self-expanding valve, like the Evolut platform. However, it is an intra-annular valve, so the leaflets sit at the level of the annulus, similar to the Sapien platform. But the leaflets are a little bit taller, so what the data show is that despite it being an intra-annular valve, the gradients are similar to those seen with the Evolut platform. Abbott is essentially proposing that this device has the benefit of the hemodynamic performance of the tall leaflets but also the intra-annular design to facilitate coronary access and redo TAVR. It is being marketed as the best of both worlds.

We have not seen the larger-series U.S. data yet. There are some European data showing that paravalular leak is less than with the Portico (Abbott) platform. There has been one randomized controlled trial looking at the Portico design compared with the self-expanding and balloon-expandable valves, but that is an older-generation valve. Therefore, we do not know how the Navitor valve will perform against some of its competitors. The platform may be amenable to patients who require lifetime management of their aortic valve disease who may require a potential reintervention and who could derive hemodynamic benefit from the lower gradient.

However, we need to see the pacemaker-implantation rate and the paravalvular leak rate. Right now, in our program, there is no moderate or severe paravalvular leak, and the rate of mild paravalvular leak is down to less than 10%, similar to what has been reported in the literature for the latest-generation valves. And we are aiming for the pacemaker rate to be less than 10%. Those are the benchmarks the Navitor platform needs to be compared to. We know that self-expanding valves tend to have higher pacemaker rates than balloon-expandable valves, but a new platform has to be at least competitive in that area, because if you talk to a patient, they will ask about the pros and cons if you tell them you want to implant a new type of valve, and you have to offer a compelling recommendation.

Also important from the operator standpoint is usability. The balloon-expandable platform is very user-friendly. It is similar to the balloon valvuloplasty platform that interventional cardiologists are used to. The Medtronic Evolut FX platform is similar, although two operators are required to deploy the valve. In both cases, the process is easily reproducible. What we will be looking at from the operator standpoint is whether the Navitor is as user-friendly as the other two platforms. Use of TAVR is growing and there is pressure to have high throughput on these procedures, with favorable outcomes and only overnight stays. A user-friendly technology means that you don’t end up spending a lot of time optimizing and performing the procedure. Once the new Navitor valve rolls out, we have to see what the procedural performance looks like. If it is competitive in terms of usability, then we will have a viable third competitor in the market. If it is not, then we will not.

Another factor to consider of course is pricing. A new device in the market could mean price competition, but it remains to be seen what Abbott’s pricing strategy will be.