Effect of a Non-polymer Titanium Dioxide Thin Film-Coated Stent with Heparin in a Porcine Coronary Restenosis Model

Abstract

Purpose The aim of this study was to examine the effect of non-polymer titanium dioxide (TiO2) thin film-coated stents modified with heparin in a porcine coronary overstretch restenosis model. Methods Pigs were randomized into three groups in which either TiO2 film-heparin coated stent (THS, n=12), zotarolimus-eluting stent with polymer (ZES, n=12), or bare metal stent (BMS, n=12) was placed in a coronary artery (18 pigs, 12 coronaries in each group). Histopathologic analysis was performed at 28 days after stenting. Results There was no significant difference in injury score among the three groups. There were significant differences in neointima area (2.9±0.85 mm2 in the THS group vs. 2.8±0.10 mm2 in the ZES group vs. 3.3±0.58 mm2 in the BMS group, P<0.05), fibrin score (0.0 [range 0.0 to 1.0] in the THS group vs. 2.0 [range 2.0 to 2.0] in the ZES group vs. 0.5 [range 0.0 to 2.0] in the BMS group, P<0.0001), and inflammation score (1.0 [range 0.0-1.0] in the THS group vs. 1.0 [range 1.0 to 2.0] in the ZES group vs. 1.0 [range 0.75 to 1.0] in the BMS group, P<0.0001) among the three groups. In-stent restenosis rate, as measured by micro computed tomography, demonstrated similar percent area values upon histology analysis (57.7±13.14% in the THS group vs. 58.7±16.44% in the ZES group 64.8±8.56% in the BMS group, P<0.05). Conclusion THS is more effective in reducing neointima formation compared to BMS. Moreover, the neointima suppressive effect of THS exceeds that of commercial ZES, with lower fibrin and inflammation scores in a porcine coronary restenosis model. Keywords: Stents, Percutaneous coronary intervention, Restenosis, Inflammation