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

Written by Debra L. Beck, MSc

Presented by Ramon L. Varcoe, MBBS, MS, PhD, MMed (ClinEpi)

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.”

Results

 

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.


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