Venous Stents: Long-term Follow-up Plus a New Contender

HOLLYWOOD, FL—Two-year data for two venous stents show primary patency rates of around 80% or higher, repeat revascularization rates hovering at approximately 10%, and no signs of stent fracture or movement.

These results, presented at the 2020 International Symposium on Endovascular Therapy (ISET), bolster the 1-year data that informed the devices’ approval by the US Food and Drug Administration mere months apart in 2019.

Venovo (BD), the focus of the VERNACULAR trial, and Vici (Boston Scientific), examined in the VIRTUS trial, are each self-expanding nitinol stents designed specifically for use in treating symptomatic iliofemoral venous outflow obstruction.

Erin Murphy, MD (Sanger Heart and Vascular, Atrium Health, Charlotte, NC), told TCTMD that there are several reasons why a dedicated device is desirable.

“The most obvious one is that having an FDA-approved product opens a lot of doors. It makes it more comfortable for the physician, more comfortable for the patient. It opens educational opportunities, to be able to do training courses [and] promote education,” Murphy observed. This is well needed because the field is so new and many physicians—even those currently doing the procedures—didn’t receive much formal training in this area, she explained.

Anatomy also poses unique challenges—venous disease requires larger and longer stents compared with peripheral artery disease. “The difficulty in making stents big enough is that when you get bigger in size, they become less strong,” she explained, noting that novel stents have addressed this issue in various ways.

Additionally, the iliofemoral vein is a “very tortuous vessel. It requires flexibility but still requires that strength, and [the stent] also has to cross the inguinal ligament” without fracturing, something Murphy stressed is especially important in young patients who will need these devices to work for many years.

In a late-breaking session, Murphy shared baseline details from the ABRE IDE Study, for which she serves as a principal investigator, looking at the Abre venous stent (Medtronic); outcomes data from that trial are expected soon.

Venovo, Vici, and Abre all have already received CE Mark approval in Europe, as has the Zilver Vena (Cook Medical), which is now being studied in the US-based VIVO trial.

VERNACULAR and VIRTUS at 2 Years

Jose I. Almeida, MD (Miami Vein Center, FL), presented results from VERNACULAR, a trial that enrolled 170 patients with iliac and femoral vein occlusive disease, including acute or chronic deep vein thrombosis and/or May-Thurner syndrome, at 22 sites in the US, Europe, and Australia. Slightly more than half had postthrombotic syndrome, while the rest had nonthrombotic iliac vein lesions. Two-year follow-up was available for 86.4% of the original cohort.

Venovo has flared ends and an open-cell design, Almeda told the audience at ISET 2020. “What I like most about it are the good range of diameters from 10 to 20 mm—the other stents [aren’t] this big—and length to 160 mm. So this really makes [the device] a lot more versatile than what we’re used to with the Wallstent,” a Boston Scientific-made device long used off-label for this indication.

By 2 years, the rate of primary patency with Venovo was 84.3% on Kaplan-Meier analysis (down from 88.6% at 1 year). Freedom from TLR and from TVR rates each were 89.4% (down from 92.6%), and no stent fractures had occurred. Follow-up will continue through 3 years, Almeida said.

In the same session, Robert Lookstein, MD (Icahn School of Medicine at Mount Sinai, New York, NY), reported 2-year results for VIRTUS. Like VERNACULAR, this trial enrolled 170 patients who had obstruction of the iliofemoral venous outflow tract, treating them with the Vici stent; three-quarters of patients were postthrombotic and one-quarter were nonthrombotic. Follow-up data were available for 88.2%.

By 2 years, VIRTUS showed a primary patency rate of 79.4% (down from 84% at 1 year) and a TVR rate of 88.7%. Patients whose disease was nonthrombotic in origin saw a 2-year primary patency rate of 96.4% (compared with 73.4% in the postthrombotic group). There were no instances of stent movement.

“This is an excellent device with excellent performance in a particularly challenging lesion subset, with continuing durable benefit even in chronic postthrombotic cases out to 24-month follow-up,” Lookstein concluded, pointing out that Vici “is the only currently FDA-approved closed-cell design [device] for the iliofemoral segment.” Vici is available in diameters of 12 to 16 mm and in lengths of 60 to 120 mm, according to the Boston Scientific website.

ABRE recently completed 12-month follow-up, Murphy noted in her ISET talk. These numbers are now being analyzed, with the expectation that they will be presented at the Charing Cross Symposium in April 2020.

‘Wait and See’

Asked by TCTMD how to make sense of the contenders in this field, Murphy said: “We can’t really comment yet on differences in the stents, in that . . . it’s too early to compare the results.”

All of these devices are nitinol-based and developed for use in venous disease, but each was designed a little bit differently and may perform in its own way, she explained. “We have to wait and see how those subtleties in design . . . will pan out clinically.”

One advantage that they all share over their off-label predecessors is having “more accurate and predictable deployment,” Murphy said. “Especially in your postthrombotic patients, it’s very difficult to land [Wallstent] precisely at the distal end. When you put it in and balloon it, it may change its length. And then at the top, the ends are a little bit weaker, so you either have to combine it with something like a Z stent [Cook Medical] and land it anatomically or you have to take it into the cava, which [risks] contralateral DVT.

“So hopefully, the new stents are a first step in finding a product that really works in this [area],” Murphy concluded.