There are several covered stents on the market that are used in an off-label setting as bridging stents for fenestrated and branched endovascular aneurysm repair (F/BEVAR). Currently, there is no consensus on when to use what—no gold standard, no proof, no evidence. According to three experts in the field, however, this is about to change. As trials take place and data begin to emerge, Vascular News speaks to Stéphan Haulon (Hôpital Marie Lannelongue, GHPSJ, Paris, France), Eric Verhoeven (Klinikum Nuremburg, Nuremberg Germany), and Tim Resch (Copenhagen Aortic Center, Rigshospitalet, Denmark), who express their views on the past, present, and future of bridging stents in FEVAR and BEVAR.
Considering the origins of bridging stents in these indications, Haulon explains that they have been used “for years”, but in an off-label sense. Nowadays, however, he relays that specific devices are being developed, and that trials are beginning to specifically evaluate bridging stents for FEVAR and BEVAR.
“I think it is important to stress that bridging stents for fenestrated endografts have different features to bridging stents for branched devices,” Haulon says. “The main difference is that we use bridging stents to connect the fenestration to the target vessel, but usually the fenestration is adjacent or close to the origin of the target vessel, so the bridging stent does not need to cross a large gap or a large aneurysm sac before going into the target vessel. In addition, it needs to be locked to the fenestration […] so there is a flaring process, whereas in branches, you have a long overlap between the bridging stent and the branch, and you have a long gap in most cases to bridge the aortic device to the target vessel,” he explains.
Resch elaborates: “In many cases of fenestrated repair for pathologies such as juxtarenal and pararenal aneurysms, where you have wall apposition of the main body of the device, the fenestrated or branched stent per se is not much for seal, but for direction, to keep patency in these vessels.”
“It means that [the] stent is much shorter and less subjected to difference forces, whereas oftentimes in a branch repair, you are actually traversing an aneurysmal space. It needs to create a whole different seal between the main body of the endograft and the target vessel and traverse a lot of space in between, so those stents are typically longer and need to display more varied properties. They have to be strong and flexible and to withstand forces of a different magnitude than bridging stents in fenestrated grafts,” he adds.
Within this context, Verhoeven highlights the fact that fenestrated and branched procedures require different types of stents. “In fenestrated grafts, or in grafts with fenestrations only, we use balloon-expandable covered stents that we can flare, while in branched grafts, we can use either self-expandable covered stents or balloon-expandable covered stents,” he states, adding that the next step in the branched setting is to have more flexible balloon-expandable covered stents to accommodate the angles between the branches and the target vessel.
Past: Expanding clinical goals and the changing role of industry
Historically, physicians did not have much choice about which stent to use, Verhoeven stresses. Resch echoes this lack of choice, recalling his experience from 15–20 years ago: “It was all about getting a graft in place, so we took whatever device we could regarding trackability and profile, and tried to get it in place.”
Nowadays, they emphasise that the aim is more focused on long-term outcomes. He explains: “Over the years, we have obtained more experience and data on what actually makes the device last, so our aim today is not just to get a device in place and get an aneurysm excluded, but to keep that aneurysm excluded over a long period of time.”
Regarding industry, Verhoeven notes that there used to be only a few companies who had the desire to develop these devices as it was a small market, but that this market has “continuously grown”.
Speaking on this changing role, Haulon remarks that, given the off-label use of these devices, the only way to get better was to combine experiences in order to try and find out which stent worked best in which indication, with little input from industry. “What is changing is that now industry is coming up with dedicated bridging stents and launching trials, so we will have real evidence,” he explains.
More specifically, Verhoeven details which devices he currently uses in his practice. “In fenestrations, we currently use the BeGraft [Bentley], which is a dedicated balloon-expandable covered stent for fenestrations, and we also use the Advanta V12/iCast [Getinge], which we have been using for years. We use both as the ‘new’ Begraft provides all the diameters and lengths we require. For branches, our first covered stent is the balloon-expandable BeGraft Plus [Bentley]. As a bailout with regard to length, we also use the VBX [Gore], because that is the only balloon-expandable covered stent that comes in a length of 79mm.”
Present: Crucially different demands of FEVAR and BEVAR highlight need for trials
The interviewed physicians are keen to stress the importance of differentiating between FEVAR and BEVAR. Recognising the unique demands of the two procedures is “crucial,” according to Resch. “There is still some confusion with regards to that in the marketplace and among users, which sometimes leads to disastrous outcomes,” he explains, using the example of BeGraft (for fenestrations) and the BeGraft Plus (for branches) as examples, stressing that they are “two totally different devices that we use for two totally different things”.
In his consideration of why the two are confused, Haulon underlines the need for data and dedicated stents: “I think the main reason is that we do not have approved bridging stents for the technology. They are being used off-label and that is why we urgently need specific trials.” He elaborates that Bentley is currently actively supporting both a FEVAR and a BEVAR physician-initiated trial with the BeGraft and the BeGraft PLUS as bridging stents that he hopes will bring the data needed to support which stents works well for which indication.
Future: The journey from off-label to on-label continues
Resch sees the gathering of data for these indications as part of an essential part of a wider project. “We have worked on main body stent graft development for many years, and it feels like the mating stents were left a bit behind, so we are very happy now that we are finally taking on the whole package, because the repair itself and its durability is really dependent on the whole graft,” he comments.
“It has been a very long journey,” Haulon adds, noting that it “felt bad” to be using stents off label for so many years. “There was a huge learning curve for everyone, and it was a niche for companies for many years,” he recalls, but adds that the need for data is evident.
“We are moving from pioneering times to a mature technology,” Haulon concluded.