Impact Of Polymer Formulations On Neointimal Proliferation Following Zotarolimus-Eluting Stent With A Different Polymer: Results Of A 3d Intravascular Ultrasound Analysis

Background: RESOLUTE is a novel stent system using newly developed biodurable polymers, which enable longer drug-elution. RESOLUTE adopts the identical stent platform and drug/drug dose to the current ENDEAVOR zotarolimus-eluting stent system. The aim of this analysis is to compare the efficacy of zotarolimus-eluting stents with different polymer formulations. Methods: Serial IVUS analyses (post-procedure and 9 months follow-up) were available in 71 patients from the ENDEAVOR II trial and in 81 patients from the RESOLUTE trial. Volume index, defined as volume data divided by stent length, was obtained for vessel (VVI), stent (SVI), lumen (LVI), plaque (PVI), and neointima (NVI). Percent neointimal volume (%NIV) was calculated as neointimal volume divided by stent volume. Cross-sectional narrowing was defined as neointimal area divided by stent area (%). Neointima-free frame ratio was calculated as the number of frames without IVUS-detectable neointima divided by the total number of frame. Results: VVI, LVI and PVI at baseline were not significantly different between the 2 groups. No significant volumetric increase from post-procedure to follow-up in VVI and PVI was observed in either stent group. At 9 months follow-up, % NIV was significantly lower in RESOLUTE compared to ENDEAVOR. Minimum lumen area at follow-up was significantly larger and late area loss was significantly smaller in RESOLUTE compared to ENDEAVOR. Neointima-free frame ratio was significantly higher in RESOLUTE compared to ENDEAVOR. Conclusion: These IVUS results demonstrate excellent suppression of neointimal proliferation throughout the stented segment in RESOLUTE compared to ENDEAVOR, suggesting that different polymer formulations significantly affect the relative amount of NIH for drug-eluting stents.