Preclinical Evaluation of a Novel Polymer-free Everolimus-eluting Stent in a Mid-term Porcine Coronary Restenosis Model

Background: Titanium dioxide films exhibit good biocompatibility and may be effective as drug-binding matrices for drug-eluting stents. We conducted a mid-term evaluation of a novel polymer-free everolimus-eluting stent using nitrogen-doped titanium dioxide film deposition (TIGEREVOLUTION (R)) in comparison with a commercial durable polymer everolimus-eluting stent (XIENCE Alpine (R)) in a porcine coronary restenosis model. Methods: Twenty-eight coronary arteries from 14 mini-pigs were randomly allocated to TIGEREVOLUTION (R) stent and XIENCE Alpine (R) stent groups. The stents were implanted in the coronary artery at a 1.1-1.2:1 stent-to-artery ratio. Eleven stented coronary arteries in each group were finally analyzed using coronary angiography, optical coherence tomography, and histopathologic evaluation 6 months after stenting. Results: Quantitative coronary analysis showed no significant differences in the pre procedural, post-procedural, and 6-month lumen diameters between the groups. In the volumetric analysis of optical coherence tomography at 6 months, no significant differences were observed in stent volume, lumen volume, and percent area stenosis between the groups. There were no significant differences in injury score, inflammation score, or fibrin score between the groups, although the fibrin score was zero in the TIGEREVOLUTION (R) stent group (0 vs. 0.07 +/- 0.11, P = 0.180). Conclusion: Preclinical evaluation, including optical coherence tomographic findings 6 months after stenting, demonstrated that the TIGEREVOLUTION (R) stent exhibited efficacy and safety comparable with the XIENCE Alpine (R) stent, supporting the need for further clinical studies on the TIGEREVOLUTION (R) stent.