Bioresorbable scaffold effectively treats below-the-knee lesions
LAS VEGAS — A bioresorbable scaffold was shown to be safe and effective for treatment of below-the-knee lesions in two studies presented at VIVA 19.
In the 5-year results of the ABSORB BTK trial of the bioresorbable scaffold (Absorb, Abbott), more than 90% of patients did not require revascularization, whereas in the 1-year results of the DISAPEAR registry, there were high rates of patency, wound healing and limb salvage.
In ABSORB BTK, at 5 years, the rate of primary patency was 72.9% and the rate of freedom from clinically driven target lesion revascularization was 90.7%, Ramon L. Varcoe, MBBS, MS, FRACS, PhD, director of operating theatres and director of the Vascular Institute at Prince of Wales Hospital, Sydney, and associate professor at the University of New South Wales, said during a presentation.
By contrast, in the only other drug-eluting stent studied for 5 years in below-the-knee lesions, the patency rate was 11.6%, he said.
In addition, he said, 95% of patients showed sustained clinical improvement at 35 months, dropping in Rutherford class.
The study included 48 patients (mean age, 82 years; 56% men; 73% with critical limb ischemia; mean lesion length, 20.1 mm) who had 71 scaffolds implanted in 55 limbs.
At 5 years, 38% of the cohort had died, but no deaths were within 30 days or attributed to the device or procedure, Varcoe said.
The device performed better in this study than in studies in coronary arteries, Varcoe said.
“The elephant in the room is that this device failed in the coronaries, and it’s worth analyzing why,” he said during a press conference. “The bottom line is: It was a first-generation device being put up against a seventh-generation advanced drug-eluting stent. And it marginally failed equivalency due to some late scaffold thrombosis. That actually boiled down to about six cases. The OCT images from some of the cases suggests poor scaffold wall apposition, which is a mode of failure. One of the reasons we got different results in this study is that we went to our coronary colleagues to ask the most appropriate technique to deploy these devices. We followed the concept of adequate predilatation, good sizing using OCT and high-pressure postdilatation. If you do that, you don’t seem to have the same scaffold thrombosis. We did not see any late scaffold thrombosis in our follow-up out to 5 years.”
In the DISAPEAR registry of 41 patients with CLI (median age, 63 years; 93% with tissue loss) treated with 69 bioresorbable scaffolds in 53 lesions (mean lesion length, 22.7 mm), the 1-year rate of primary patency was 86% and the 1-year rate of freedom from clinically driven TLR was 93%, Steven Kum, MD, director of vascular surgery in the department of surgery, Changi General Hospital, Singapore, said during a presentation.
At 1 year, amputation-free survival occurred in 85% of patients, whereas the limb salvage rate was 98% and the rate of wound healing in the patients with tissue loss was 79.5%, Kum said, noting that median time to wound healing was 4 months.
“There may be a role for scaffolds and drug elution for reliable lumen gain and consistent drug elution,” Kum said during the presentation. “Our experience in the DISAPEAR registry is encouraging.”
The next step is a new trial with the next generation of the device, Varcoe said.
The previous trials “generated important data that suggest this device has a lot of potential, and future iterations of it should be evaluated in the form of a multicenter randomized controlled trial,” he said during his presentation.
That trial, LIVE-BTK, is now planned, he said, noting it is an FDA investigational device exemption trial expected to enroll 225 patients from 50 sites in the United States and elsewhere.
Patients will be randomly assigned on a 2:1 basis to the next generation of the bioresorbable scaffold (Esprit, Abbott) or percutaneous transluminal angioplasty. The primary endpoints will be reported at 6 months, but patients will be followed for 5 years, Varcoe said. – by Erik Swain
Kum S, et al.
Varcoe R, et al. Late-Breaking Clinical Trials. Both presented at: VIVA 19; Nov. 4-7, 2019; Las Vegas.
Disclosures: Kum reports he has financial ties with Abbott, Boston Scientific and LimFlow. Varcoe reports he consulted for and/or received honoraria from Abbott Vascular, Boston Scientific, Intact Vascular, Medtronic, Shockwave Medical and Surmodics.