Pathological evaluation 18 years after bare-metal stent implantation in the superficial femoral artery

摘要

Bare-metal stents (BMSs) have been generally applied for the treatment of peripheral artery disease in patients with femoropopliteal disease. However, very long-term pathological findings after BMS implantation have not been elucidated to date. We experienced an autopsy case in which we performed a pathological evaluation 18 years after BMS implantation in the right superficial femoral artery. The BMS was totally occluded and filled with remarkable neointima formation. Neointima was mainly composed of a lot of rather atrophic smooth muscles and intercellular spaces containing dense collagenous fibers. Furthermore, regional fatty infiltration was also observed, but inflammatory cell infiltration, such as macrophages and lymphocytes, was not recognized obviously even around the struts. Judging from the pathological findings, the main mechanism of the very long-term in-stent restenosis in the patients with femoropopliteal disease was continuous proliferation of smooth muscle cells that led to the totally occlusive disease. This observation leads us to speculate that continuous elution of an anti-proliferating drug over a longer duration, at least beyond 1 year, would be effective to prevent chronic-phase restenosis. Further development of devices that can be used in the femoropopliteal artery is needed in light of this speculation.