Comparative effects of sirolimus-eluting versus bare metal stents on neointimal hyperplasia in balloon-injured external iliac artery of rabbits

The aim of this study was to check effectiveness of drug-eluting stents for prevention of restenosis resulting from neointimal hyperplasia. Twenty-one sirolimus-eluting stents (SESs) and bare metal stents (BMSs; control) were compared by implantation into left and right balloon-injured external iliac arteries of New Zealand White rabbits, respectively. Under general anesthesia and angiography, using 3-mm coronary balloon catheters, stents were successfully deployed. Anticoagulant therapy was not given to any animal. Rabbits were allotted into three groups at 7, 14, and 21 days (7 rabbits in each group). Each stented vessel of sacrificed rabbits was subjected to a resin-embedding technique and methyl methacrylate sections were obtained using a tungsten carbide knife for staining. In histological examination, SESs showed marked reductions in almost all parameters. Morphometric results showed that arteries with SESs had a larger luminal area (P < 0.0001), lower intimal (P < 0.001) and medial (P < 0.001) thickness, and lower intimal index (P < 0.003) as opposed to arteries stented with BMSs. Luminal narrowing in SESs was 0% and reendothelialization was similar in both stented groups (90.48%). SESs showed marked reduction in nonocclusive peristrut fibrin deposition versus BMSs. Thus, the SES was more effective for prevention of restenosis than the BMS in rabbit.