Long-term Outcomes for Resorbable DES for BTK Applications and LIFE-BTK Trial Update

Evidence continues to accrue for the use of bioresorbable vascular stents (BVS), with the first-generation Absorb device (Abbott) showing excellent long-term patency and freedom from target lesion revascularization (TLR) in the tibial arteries.

Ramon L. Varcoe, MBBS, MS, PhD, MMed (ClinEpi), a vascular surgeon at the Prince of Wales Hospital and University of New South Wales in Randwick, Australia, presented the ISET 2022 audience the 5-year findings for the Absorb device and an update on resorbable drug-eluting scaffolds for BTK applications.

“For many years now, we’ve been using drug-eluting stents below the knee and that’s because we know they work from several randomized controlled trials attesting to that fact. But they do leave behind a permanent metallic scaffold, which can be an impediment to future surgery, intervention, and even cross-sectional imaging,” said Varcoe.

These limitations have led investigators to wonder if a drug-eluting bioresorbable scaffold might be the best of both worlds. “It can provide that mechanical scaffolding, it’s a vehicle for anti-proliferative drug deliver, it also allows the return of normal vessel wall function in terms of contractility, and then it disappears completely, leaving nothing behind.”

In a prospective, non-randomized, single-arm, single-center study, Varcoe and colleagues enrolled 48 patients (55 limbs) with chronic lower-limb ischemia (Rutherford class 3-6), with life expectancy greater than 1 year, single or multiple de novo lesions >60%, and maximum total lesion length of 5 cm or less and diameters of 2.5 to 4.0 mm.

The majority of patients (56%) were male and mean age was 82.1 years. Most were treated for critical limb ischemia (72.7%); 27.3% had severe claudication.

A total of 71 scaffolds were implanted in 61 lesions (mean lesion length, 20.1 mm). The researchers saw 100% procedural and technical success.

“We had 18 deaths, which represented 38% of the cohort,” reported Dr. Varcoe (see below). “Now this is typical of what we see in a CLI population…you lose a lot of these patients in follow-up. All of those deaths were outside the 30-day window and all were unrelated to the device or the procedure.”

In the 5-year results published in Catheterization and Cardiovascular Interventions in January 2021 (Volume 97, Issue 1), 22 patients had died during a mean follow-up period of 35.1 months. There were no reports of late or very-late scaffold thrombosis, although binary restenosis was detected in 11/71 (15.5%) scaffolds.

Primary patency and freedom from clinically driven target lesion revascularization rates at 60 months were 72.9% and 90.7%, respectively.

“In conclusion, this first-generation Absorb drug-eluting bioabsorbable scaffold has achieved excellent long-term patency and freedom from CD-TLR rates in the tibial arteries and in my mind, this acts as a proof of concept for the next generation of BVS devices and a larger evaluation in the form of a multicenter randomized controlled trial, which is what we’re doing currently,” said Varcoe.

The pivotal LIFE-BTK is a prospective, randomized, multicenter US and out-of-US single-blind trial that will include 225 patients randomized in a 2:1 fashion to the ESPRIT BTK versus PTA. Patients will be followed for 5 years, looking at a safety endpoint of absence of major adverse limb events and death, and an efficacy endpoint of primary patency and limb salvage.

As of now, a total of 160 patients have been randomized at 52 active enrolling sites, reported Varcoe. The investigators hope to complete enrollment by March 2022.