BACKGROUND: The vascular healing response is an important factor in the development of restenosis and stent thrombosis. This study was designed to evaluate the vascular healing of bare metal stents (BMS) compared to everolimus (EES) and beta-estradiol (BES) eluting stents in a chronic atherosclerotic experimental animal model of thin cap fibroatheroma (TCFA). METHODS: Sixteen New Zealand hypercholesterolemic rabbits followed for 4 years were studied. Six animals received BMS, 5 EES, and 5 BES (Guidant, Santa Clara, CA). One polymer stent per animal was also implanted. RESULTS: Histologic analysis at 28 days of de-novo vs. BMS, EES, and BES stented TCFA showed polymer stents induced a higher fibrin and hemorrhage score. BES induced higher inflammation and fibrin scores and a lower endothelization score. EES induced higher inflammation, fibrin and hemorrhage scores. BES and EES induced similar healing scores. Percent collagen I areas were similar in all 4 types of stents. Percent collagen III areas were higher in BMS when compared to polymer and drug-eluting stents. CONCLUSION: Drug-eluting stents are associated with low but increased inflammation, fibrin deposition and hemorrhage which seem to be related to the polymer's vascular effects.
Atherosclerosis; Stents; Drug-eluting stents; Models, animal; Rabbits
