Pathology of Neointimal Calcification in Very Late Restenosis After Bare Metal Stent Implantation for Superficial Femoral Artery.

A 60-year-old man, who had claudication in his right limb due to total occlusion of the right superficial femoral artery, received bare metal stents. Although the bare metal stents in the superficial femoral artery did not show restenosis 5 years after stent implantation, angiography revealed significant in-stent restenosis when he developed right critical limb ischemia at 8 years post implantation. Ballooning for in-stent lesions did not result in full expansion. His right limb was amputated above the knee due to progressive limb ischemia. In the pathological findings in the superficial femoral artery, marked calcification was observed in the entire circumference of the luminal surface of the neointima. However, lipid core formation was not identified in the neointima. Although several cracks following balloon angioplasty were observed at the superficial calcified layers, injury to neointimal tissue such as compression was not observed. The neointima exhibited heavy calcification in the very late phase of in-stent restenosis after bare metal stent implantation in superficial femoral artery. Therefore, balloon angioplasty in the very late phase of in-stent restenosis potentially results in underexpansion.