Drug-eluting, balloon-expandable, bioresorbable vascular scaffolds reduce neointimal thickness and stenosis in an animal model of percutaneous peripheral intervention

Objective

Recanalization with balloon angioplasty and/or self-expanding stents (SES) has become the endovascular treatment of choice for symptomatic femoropopliteal occlusive disease. These strategies generate suboptimal clinical results, however, because they fail to expand the artery fully and ineffectively prevent recoil, neointimal hyperplasia, and restenosis. Balloon-expandable stents, given their greater radial force and rigid structure, represent a more effective treatment strategy, but only short lengths can be implanted safely in arteries that deform and bend with skeletal motion. The purpose of this preclinical experiment was to test the hypothesis that simultaneous implantation of a series of short, resorbable, balloon-expandable, paclitaxel-eluting scaffolds would prevent neointimal hyperplasia and stenosis compared with SES in an animal model of percutaneous femoropopliteal intervention.

Methods

We extruded 6 × 60 mm Efemoral Vascular Scaffold Systems (EVSS) from copolymers of poly-L-lactic acid, coated with paclitaxel 3 μg/mm², crimped onto a single delivery balloon, and implanted percutaneously into the iliofemoral arteries of eight Yucatan mini-swine. We implanted 7- to 8-mm × 60 mm SES into the contralateral experimental arteries. The animals were serially imaged with contrast angiography and optical coherence tomography after 30, 90, 180, 365, and 730 days. The primary end point of this study was neointimal morphometry over time. Secondary end points included acute deformation and angiographic and optical coherence tomography-derived measurements of chronic vascular response.

Results

Over the 2-year study period, one SES was found to be completely occluded at 90 days; all EVSS were widely patent at all time points. Arteries treated with SES exhibited profound neointimal hyperplasia with in-stent stenosis. In contrast, arteries treated with EVSS exhibited only modest vascular responses and minimal stenosis. After 2 years, the mean neointimal thickness (0.45 ± 0.12 vs 1.31 ± 0.91 mm; P < .05) and area (8.41 ± 3.35 vs 21.86 ± 7.37 mm²; P < .05) were significantly decreased after EVSS implantation. By 2 years, all scaffolds in all EVSS-treated arteries had resorbed fully.

Conclusions

In this preclinical animal model of peripheral endovascular intervention, the EVSS decreased neointimal hyperplasia and stenosis significantly compared with SES, then dissolved completely between the first and second years after implantation.