BVS Reboot? Signs of Durability to 2 Years in Critical Limb-Threatening Ischemia

The use of bioabsorbable vascular scaffolds (BVS) in patients with critical limb-threatening ischemia (CLTI) results in durable patency out to 24 months, with a high rate of freedom from major amputation, according to a pooled analysis of single-center registries.

“In CLTI, which is plagued by frequent reinterventions, poor patency and high mortality, BVS with consistent drug delivery [from an] absorbable scaffold may have a role to play, said Steven Kum, MD (Changi General Hospital, Singapore), in a presentation at VIVA 2020.

The pooled analysis of 121 patients consisted of single-center cohorts from Singapore treated in the DISAPEAR registry, Australian patients treated in the ABSORB BTK registry, and a group from an unnamed Chicago study. All three experiences involved the everolimus-eluting ABSORB BVS (Abbott Vascular), which elutes 80% of the drug within 28 days. The scaffold is fully absorbed by 3 years.

As Kum showed, the rate of primary patency in the pooled analysis was 86.6% at 24 months, and freedom from clinically driven TLR was 96.6%, with only one patient requiring major amputation.

Patients in the analysis ranged in age from 73 to 97 years, and approximately 60% were diabetic. All were Rutherford class 3-6, and most had tissue loss. Lesion lengths averaged 21 mm, and 63% were calcified. The most commonly used scaffold size was 28 mm, with the goal being total lesion coverage. If more than one scaffold was required, consecutive devices were abutted or overlapped with a maximum overlap of 1 mm.

In a video, Kum showed how an elderly female patient with a Rutherford 6 gangrenous heel had successful healing of the wound following the procedure, and at 3.5 years was walking unassisted, having required no reinterventions.

Moving Ahead but Mindful

Originally developed for the cardiac space, high hopes for the BVS were dashed when concerning 2-year data from the ABSORB III study of CAD patients emerged, showing higher rates of target lesion failure driven by MI. Additionally, the 3-year data from ABSORB II found no improvement in vasomotor tone, increased late lumen loss, and a two-fold increased risk of device-oriented clinical events compared with an everolimus-eluting metallic stent.

With those past failures in mind, moderator Peter Schneider, MD (University of California, San Francisco), wondered whether the poor results in CAD would affect how regulatory authorities assess the safety and efficacy of the device for peripheral vascular indications.

We recognize that both the patient population and the lesion characteristics between the coronaries and the lower limb interventions are different. Misti Malone

“We do look at all of the available information, but we recognize that both the patient population and the lesion characteristics between the coronaries and the lower limb interventions are different,” noted panelist Misti Malone, PhD (US Food and Drug Administration, Silver Spring, MD). Given the high rates of amputation and mortality in the CLTI population, she said the data and video evidence like that shown by Kum of patients regaining their movement, would be taken into consideration.

“We think of the patient population, their potential benefits, and how this device will act in that particular anatomy,” Malone added. “So, different circulation, different lesion characteristics.”

Kum noted that more data will be forthcoming from the ongoing FDA-approved investigational device exemption trial, LIFE-BTK. The multicenter trial, with a planned follow-up of 5 years, is randomizing 225 patients to a new-generation BVS called Esprit (Abbott Vascular) or percutaneous transluminal angioplasty.

Another issue, added Schneider, is that below-the-knee lesions are often long and diffusely diseased, which poses challenges for deciding where and when to place short BVS.

Kum said while the study “helps to give us an idea of proof-of-concept of how it would perform in a longer lesion,” the scaffold would likely be best used as a secondary adjunct during revascularization to get more blood to the foot.