BACKGROUNDFirst generation drug-eluting stents (DESs) were based on 316L stainless steel and coated with a permanent polymer. The vessel wall of these DESs was inflammatory and late in-stent thrombosis was reported. Hence, cobalt chromium based DES coated with a bioabsorbable polymer was an alternate choice.

METHODSCobalt chromium based DES with bioabsorbable polymer (Simrex stent) as well as control stents (Polymer stent and EXCEL(TM) stent) were implanted into porcine arteries. At a designated time, angiography, quantitative coronary angiography (QCA) analysis, histomorphometry, and electron-microscopical follow-up were performed.

RESULTSA total of 98 stents of all the three groups were harvested. At week 24, percent diameter stenosis (%DS), late loss (LL), and percent area stenosis (%AS) of Simrex was (12.9 ± 0.4)%, (0.35 ± 0.02) mm, and (24.5 ± 4.2)%, respectively, without significant difference in comparison to commercialized EXCEL(TM) stent. Slight inflammatory reaction was seen around the stent strut of Simrex, just as in the other two groups. Electron-microscopical follow-up suggested that it might take 4 - 12 weeks for Simrex to complete its re-endothelialization process.

CONCLUSIONSCobalt chromium based, bioabsorbable polymer coated sirolimus-eluting stent showed excellent biocompatibility. During 24 weeks observation in porcine model, it was proved that this novel DES system successfully inhibited neointima hyperplasia and decreased in-stent stenosis. It is feasible to launch a clinical evaluation to improve the current prognosis of DES implantation.