Abstract 10956: Early and Late Vascular Responses After Stent Implantation in Human Peripheral Artery Disease
Background: Although stent implantation is now a first-line strategy for the treatment of peripheral artery disease (PAD), little is known about the pathological findings of arterial response following lower extremity stenting.
Methods and Results: Histopathological studies were performed on 13 iliofemoral lesions (les) obtained by autopsy or surgical resection between 2.5 months (M) and 10 years (Y) after bare metal stent (BMS) implantation. In addition, paclitaxel-coating stents (Zilver PTX) (6 les; 10 M to 2.5 Y) implanted in superficial femoral arteries were also observed. Almost all arterial specimens were characterized by fibrocalcific intimal plaques as well as underlying Mönckeberg’s medial calcinosis. There were fibrin deposits around the struts, with smooth muscle cell (SMC) infiltration in varying degrees, at 2.5 M after BMS implantation; however, endothelial cell coverage remained poor in the surface area. Furthermore, stent malapposition is a frequent phenomenon, which is related to underlying medial and intimal calcification. Arteries from more than 1 Y after stenting exhibited thickened neointima consisting of significant proliferation of SMCs and abundant extracellular matrix on the intimal side of the stent struts. However, uncovered malapposed struts with fibrin deposition were still evident, predominantly at the calcified surface. In neointima of more than 8 Y after stenting, SMCs were spindle-shaped and ordered along the luminal surface, and intercellular space contained abundant collagen fibers. However, there was advanced luminal narrowing in 2 of the les, and the luminal surface of these segments was focally disrupted and covered by mural thrombi. Zilver PTX demonstrated notable uncovered struts, even more than 2 Y after stenting, and extensive in-stent thrombi were observed in all stented segments, including 2 les with occlusive thrombosis. Conclusions: These findings suggest that a longer duration of potent antiplatelet therapy may be more appropriate after BMS implantation for PAD, compared to coronary artery stenting. Furthermore, remarkable delayed healing with significant uncovered struts caused by paclitaxel exposure can result in late stent thrombosis after Zilver PTX implantation.
Author Disclosures: K. Inoue: None. Y. Kobayashi: None. T. Ishihara: None. T. Shiraki: None. Y. Tomoi: None. S. Hiramori: None. Y. Soga: None. O. Iida: None. K. Ando: None. M. Uematsu: None. M. Nobuyoshi: None.
- © 2015 by American Heart Association, Inc.