Bioresorbable scaffold superior to angioplasty for treating chronic limb-threatening ischemia
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Key takeaways:
- A bioresorbable scaffold improved outcomes in patients with chronic limb-threatening ischemia compared with angioplasty.
- The device has the potential to benefit a population for which there are few treatments.
SAN FRANCISCO — An everolimus-eluting bioresorbable scaffold was superior to angioplasty for the treatment of patients with chronic limb-threatening ischemia, according to the results of the LIFE-BTK trial presented at TCT 2023.
Researchers randomly assigned 261 patients with chronic limb-threatening ischemia (CLTI) on a 2:1 basis to receive the scaffold (Esprit BTK Everolimus Eluting Resorbable Scaffold System, Abbott) or conventional balloon angioplasty. The mean age was 73 years in the scaffold group and 71 years in angioplasty group; women represented 32% in the scaffold group and 31% in the angioplasty group.
“If not treated expeditiously, [CLTI] can result in in high rates of amputation,” Ramon L. Varcoe, MBBS, MS, FRACS, PhD, MMed (ClinEpi), 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 press conference. “Amputation is not only a terrible thing for an individual, but also has a prognosis worse than the majority of cancers.”
The results were simultaneously published in The New England Journal of Medicine.
‘Limited options’
“Patients with CLTI below the knee have very limited options. It is a devastating disease,” Jennifer Jones-McMeans, divisional vice president of global clinical affairs for Abbott’s vascular business, told Healio. “Once diagnosed with CLTI, the patient’s timeline of therapeutic options and keeping the vessel open can be limited. In the U.S., there are limited options. The standard of care is plain balloon angioplasty; there is no drug. These patients become what we call ‘frequent fliers,’ who have to come back multiple times to keep those diseased arteries open. Our drug-eluting scaffold was approved in the coronary space in and outside the U.S. One of the [principal investigators], Dr. Ramon Varcoe, had started investigating it below the knee in his practice. He was seeing some very good results with patency. He even had data out to 5 years where the decline over time in patency was not as severe as what we have seen with plain balloon angioplasty. With his continued work, we decided to bring this technology to the FDA and have a U.S. trial. Esprit is currently still under investigation and is not approved by the FDA.”
The device “provides the mechanical scaffolding of a stent, but then dissolves over time, leaving nothing behind,” Varcoe said at the press conference. “It also has an antiproliferative drug on the surface that prevents restenosis.”
Superior outcomes
The primary efficacy endpoint of freedom from amputation above the ankle of the target limb, occlusion of the target vessel, clinically driven revascularization of the target lesion and binary restenosis of the target lesion at 1 year occurred in 74% of the scaffold group compared with 44% of the angioplasty group (absolute difference, 30 percentage points; 95% CI, 15-46; one-sided P for superiority < .0001), according to the results presented. Varcoe said the results were similar at 393 days, and a landmark analysis showed that after 6 months, the rate in the angioplasty group dropped but the rate in the scaffold group did not.
The primary safety endpoint of freedom from perioperative death and from major adverse limb events at 6 months occurred in 97% of the scaffold group and 100% of the angioplasty group (absolute difference, –3 percentage points; 95% CI, –6 to 0; one-sided P for noninferiority < .001), according to the researchers.
The first powered secondary endpoint of binary restenosis of the target lesion at 1 year favored the scaffold group (23.5% vs. 49.3%; absolute difference, –25.8 percentage points; one-sided P for superiority < .0001), as did the second powered secondary endpoint of freedom from above-ankle amputation of the target limb, 100% total occlusion of the target vessel and clinically driven target lesion revascularization at 1 year (83.2% vs. 69%; absolute difference, 14.2 percentage points; one-sided P for superiority = .0081), Varcoe said.
Scaffold thrombosis, which was an issue for some patients when bioresorbable technology was used in coronary arteries, was not a problem in LIFE-BTK, Varcoe said.
“The bottom line is that these are very different vascular beds,” Varcoe said. “And there are very different consequences to late thrombosis. Even if we were to see late thrombosis in the legs, you wouldn’t expect disastrous consequences like the coronaries, which makes it a much more forgiving geographical location to use it in.”
“We have extended the time to retreatment, where before, with balloon angioplasty, the subsequent retreatments can be very frequent,” Jones-McMeans told Healio. “It’s burdensome and devastating to the patient. It’s frustrating for the physician because they don’t have the availability of technologies that can help these patients with their current management of disease. The reason why this is landmark is because the CLTI below-the-knee treatment exists in a space where trials have continued to fail. Now we potentially, pending review, have a new therapy where the blood vessels can stay open over time.”
Reference:
Perspective
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This study has the potential to impact clinical practice for this very challenging and difficult-to-treat cohort with CLTI. The ability of the investigators to achieve significant improvement in their primary endpoints is the most important aspect of the trial. These efficacy and safety endpoints are very clinically meaningful for the patients. Freedom from amputation is essential from a patient perspective as well as from the treating clinician’s perspective. The maintenance of patency and absence of occlusion in the target vessel, the absence of a need to reintervene on the treated segment of the treated vessel and the absence of binary restenosis, which is a test of the purpose of the scaffolding and the intervention, are also very important. Improvement in these endpoints results in a very powerful finding for the trial.
The investigators should be congratulated on the conduct of the trial. It was a challenge to perform, and they did so effectively with the randomization protocol and the outstanding maintenance of participation of the patients, with follow-up of almost 90% in both groups. As a result, this trial has tremendous potential to influence clinical treatment.
As someone who treats these patients, I am excited to have this novel therapeutic option for treating our patients. This could alter the way we manage our patients, and in doing so result in improved outcomes.
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Varcoe RL, et al. Late-breaking clinical trials: Session II, in collaboration with The Lancet. Presented at: TCT Scientific Symposium; Oct. 23-26, 2023; San Francisco (hybrid meeting).
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