Comparison of Vascular Responses Following New-Generation Biodegradable and Durable Polymer-Based Drug-Eluting Stent Implantation in an Atherosclerotic Rabbit Iliac Artery Model.

BACKGROUND: Incomplete endothelialization is the primary substrate of late stent thrombosis; however, recent reports have revealed that abnormal vascular responses are also responsible for the occurrence of late stent failure. The aim of the current study was to assess vascular response following deployment of biodegradable polymer-based Synergy (Boston Scientific) and Nobori (Terumo) drug-eluting stents and the durable polymer-based Resolute Integrity stent (Medtronic) in an atherosclerotic rabbit iliac artery model.

METHODS AND RESULTS: A total of 24 rabbits were fed an atherogenic diet, and then a balloon injury was used to induce atheroma formation. Synergy, Nobori, and Resolute Integrity stents were randomly implanted in iliac arteries. Animals were euthanized at 28 days for scanning electron microscopic evaluation and at 90 days for histological analysis. The percentage of uncovered strut area at 28 days was lowest with Synergy, followed by Resolute Integrity, and was significantly higher with Nobori stents (Synergy 1.1±2.2%, Resolute Integrity 2.0±3.9%, Nobori 4.6±3.0%; P<0.001). At 90 days, inflammation score was lowest for Synergy (0.27±0.45), followed by Nobori (0.62±0.59), and was highest for Resolute Integrity (0.89±0.46, P<0.001). Foamy macrophage infiltration within neointima (ie, neoatherosclerosis) was significantly less with Synergy (0.62±0.82) compared with Nobori (0.85±0.74) and Resolute Integrity (1.39±1.32; P=0.034).

CONCLUSIONS: The biodegradable polymer-coated thin-strut Synergy drug-eluting stent showed the fastest stent strut neointimal coverage and the lowest incidence of neoatherosclerosis in the current animal model.