Peripheral Disease: Bioresorbable Stents in Below-the-Knee Arterial Disease

 Below-the-knee (BTK) arterial disease poses significant challenges in managing peripheral artery disease (PAD), especially in patients with chronic limb-threatening ischemia (CLTI).

CLTI is marked by ischemic rest pain or tissue loss lasting over two weeks, with a mortality rate of 20-25% at one year.

Over 70% of patients with diabetes and CLTI experience BTK disease, where revascularization is critical.

Managing BTK lesions remains difficult due to small vessels, comorbidities like diabetes and renal disease, and diffuse, calcified lesions.

Bioresorbable stents (BRS) aim to address vascular recoil, flow-limiting dissection, and restenosis through drug-eluting bioresorbable scaffolds (DRS).

BRS offer mechanical support and drug delivery while gradually dissolving over time.

They help maintain native vessel anatomy, natural vasomotion, and options for future interventions.

Simultaneous drug elution prevents restenosis by reducing inflammation after angioplasty.

BRS use polymers like poly-L-lactic acid (PLLA) and corrodible metals like magnesium and iron alloys.

PLLA scaffolds degrade into lactic acid, processed via the Krebs cycle.

Magnesium-based stents offer biocompatibility and radial strength but require slower degradation to optimize support.

Iron alloys provide high radial strength but raise concerns about iron oxide accumulation.

Initial studies with AMS stents showed mixed results for patency and revascularization.

The ABSORB BVS demonstrated promising 12-month survival and patency rates in CLTI patients.

The LIFE-BTK trial revealed superior outcomes with the Esprit scaffold compared to standard angioplasty.

The RESOLV I trial confirmed safety and efficacy with high patency rates in initial human studies.

Radial strength of BRS diminishes over time, posing risks for heavily calcified lesions.

Limited scaffold sizes and lengths complicate treatment of long BTK segments.

Optimizing scaffold support duration and improving material composition are key research areas.

Future advancements could make BRS the standard in BTK PAD management by combining temporary scaffolding with vessel restoration.

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Take-Home Points

• Bioresorbable stents (BRS) offer temporary support and drug delivery in BTK PAD.
• Polymers and metals like PLLA, magnesium, and iron are core components of current BRS.
• Clinical trials, including LIFE-BTK, highlight superior outcomes with newer-generation scaffolds.
• Challenges include limited radial strength, scaffold size constraints, and material optimization.
• Future advancements may position BRS as a transformative solution in BTK interventions.