Vascular Response After Zilver PTX Stent Implantation for Superficial Femoral Artery Lesions

Abstract

Purpose: To compare the vascular response after paclitaxel-coated nitinol drug-eluting stent (Zilver PTX) implantation for superficial femoral artery lesions after 6 and 12 months using optical coherence tomography (OCT). Methods: Serial OCT examinations were performed in 5 patients (4 men; mean age 78.4±6.8 years) with 9 Zilver PTX stents at 6- and 12-month follow-up. Variables evaluated included neointimal thickness and apposition on each strut, the incidence of extrastent lumen (ESL), peristrut low-intensity area (PLIA), and neovascularization at 1-mm intervals. Results: A total of 249 matched cross-section images were evaluated and included 4788 and 4826 struts at 6 and 12 months, respectively. Mean neointimal thickness significantly increased from 480 to 540 µm between 6 and 12 months (p<0.001). The percentage of uncovered struts tended to decrease at 12 months (3% vs. 2.3%, p=0.054), whereas the percentage of malapposed struts were similar at both examinations (0.2% vs. 0.2%, p>0.99). Although the incidence of ESL in cross sections was not different (35% vs. 31%, p=0.29), median ESL area significantly increased from 6 to 12 months [0.12 (0.04–0.36) vs. 0.31 (0.14–0.59) mm2, p=0.003)]. The presence of PLIA (29% vs. 44%, p<0.001) and neovascularization (14% vs. 27%, p<0.001) increased from 6 to 12 months. Conclusion: These findings suggest that delayed vascular healing and persistent peristent inflammation may be present even at 12 months after Zilver PTX implantation.