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SAN FRANCISCO -- The Esprit BTK drug-eluting resorbable scaffold proved safe and effective for patients with chronic limb-threatening ischemia (CLTI) and infrapopliteal artery disease, the Life-BTK randomized controlled trial showed.

The trial's primary efficacy endpoint -- 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 -- reached 74% in the scaffold group, a significantly better result for limb salvage and primary patency, compared with 44% in controls receiving percutaneous transluminal angioplasty (PTA).

This "clearly superior" finding, driven by reduced binary stenosis, total occlusion, and revascularization, translates to a number needed to treat of 4, reported Ramon Varcoe, MBBS, PhD, of the Prince of Wales Hospital and University of New South Wales in Randwick, Australia.

Both Esprit and PTA groups showed nearly total freedom from major adverse limb events at 6 months and from perioperative death, giving Esprit BTK noninferiority for safety, Varcoe reported here at the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation. The study was also published simultaneously in the .

The Esprit scaffold may thus overcome some of angioplasty's durability issues in CLTI, which is the most severe manifestation of peripheral artery disease (PAD) and requires frequent reintervention and often results in amputation.

Varcoe noted that the Esprit was borne from a successful initial experience using an older coronary scaffold in peripheral arteries. Sharing many similarities with the original Absorb device, the Esprit features a backbone containing 100% poly-L-lactic acid and struts measuring 99 µm in thickness. Its coating is comprised of everolimus and bioresorbable poly(D,L-lactide).

"Infrapopliteal arteries just lend themselves better to this technology," said Varcoe, alluding to the dangerous stent thrombosis that put a halt on using the first-generation Absorb in the coronaries.

For infrapopliteal revascularization, having a resorbable mechanical scaffold with an antiproliferative coating is thought to prevent acute lesion recoil, facilitate vessel remodeling, restore vasomotor function, help wound healing, and ultimately reduce reinterventions and adverse limb outcomes from restenosis, while avoiding the complications of permanent metal stents.

Life-BTK hasn't really proven this concept, but the hope is that the technology will pan out with longer follow-up, Varcoe said.

At a TCT press conference, Ajay Kirtane, MD, of NewYork-Presbyterian Hospital/Columbia University Irving Medical Center in New York City, pointed to the ongoing controversy over what the best interventional approach is below the knee.

showed that endovascular treatment outperformed vein bypass for preventing adverse outcomes in a Life-BTK-like population. BEST-CLI, however, gave surgical revascularization the upper hand for PAD in terms of fewer major adverse limb events and deaths compared with endovascular therapy.

Life-BTK at least shows that if one is going to use an endovascular approach, the scaffold has the potential to be "best in therapy" when used for this indication, Kirtane commented.

The trial was conducted at 50 clinical sites with 66 unique operators, and included patients with CLTI who had infrapopliteal artery stenosis or occlusion.

Participants were randomized to everolimus-eluting resorbable scaffold implantation with predilation for the procedure (n=173) or standard angioplasty (n=88). The use of the scaffolds in the trial was restricted to the proximal two-thirds of the infrapopliteal arteries.

Dual antiplatelet therapy was continued for at least 1 year in the scaffold group and for 1 month in the angioplasty group, after which patients dropped down to a single antiplatelet.

The cohort had a mean age of 72.6 years. Women comprised one in three individuals.

Patients were roughly split between those classified as having ischemic rest pain (Rutherford-Becker class 4) or minor tissue loss (Rutherford-Becker class 5). There was a wound on the target limb in half the cohort, and the mean ankle-brachial index of the target limb was 0.88. Mean lesion length at baseline was 43.8 mm in the Esprit group and 44.8 mm in controls.

Serious adverse events related to the index procedure occurred in 2% of the patients in the scaffold group and 3% of those in the angioplasty group.

Varcoe acknowledged that the primary efficacy endpoint of Life-BTK had been amended to include binary restenosis after an interim analysis at 12 months. Without this added component, the original primary endpoint (now a secondary endpoint) still favored Esprit BTK (82.5% vs 70.4%, P=0.0081).

Another limitation was the trial population had shorter lesions compared with what is usual in real-world practice. Whether study findings apply to other anatomical locations is also unclear.

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