Impact of poor below-the-knee run-off on stent failure of femoro-popliteal arteries in healthy swine model

Abstract

Abstract Background Poor below-the-knee (BTK) run-off is reported to be one of the predictors of stent failure after endovascular treatment to femoro-popliteal arteries (1), however, the mechanism of stent failure has never been characterized before. The aim of the current study was to evaluate impact of poor BTK run-off on stent failure in healthy swine femoro-popliteal (FP) lesions, and to compare the outcome of a bare-metal stent (BMS) and two drug-eluting stents (DES) in the arteries with poor BTK run-off. Method Fluoropolymer-coated paclitaxel-eluting stents (FP-PES, Eluvia) and BMS were implanted in bilateral femoral arteries of 6 healthy swine following coil embolization in both tibial arteries to induce poor BTK run-off. FP-PES and polymer-free paclitaxel-coated stents (PF-PCS, Zilver-PTX) were also implanted in 6 swine with the same fashion. Angiography with an optical coherence tomography (OCT) at one month followed by histological analysis was performed for each lesion. Result Angiography demonstrated that in-stent restenosis was observed exclusively in BMS, and percent stenosis was significantly less in FP-PES compared with BMS (FP-PES vs. BMS, median [interquartile range (IQR)], 17.8% [16.6–28.7] vs. 79.3% [64.2–87.2], respectively, p=0.03). FP-PES also demonstrated significantly less percent stenosis compared with PF-PCS (FP-PES vs. PF-PCS, 8.9% [4.7–44.7] vs. 31.2% [23.3–51.2], respectively, p=0.03). Histopathological evaluation demonstrated that organizing and/or organized fibrin thrombus was the main feature of the restenotic lesions, suggesting a risk of thrombus attachment in the FP lesions with poor BTK run-off. Biologic drug effect such as medial smooth muscle cell (SMC) loss score was significantly greater in FP-PES compared with BMS (4.0 [3.3–4.0] vs. 2.0 [1.0–3.0], respectively, p<0.01), whereas, similar between FP-PES and PF-PCS (4.0 [3.0–4.0] vs. 4.0 [3.0–4.0], respectively, p=0.88). Conclusion Thrombus attachment would be the main causes of restenosis in FP lesions with poor BTK runoff. The results of the current study suggest that not only paclitaxel drug effect, but also anti-thrombotic effect of fluoropolymer might be needed to prevent stent failure. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): This study is supported by Boston Scientific.