Histologic comparison of coronary and iliac atherectomy tissue from cases of in-stent restenosis

Pathologically, restenotic lesions after stenting were investigated by use of atherectomized tissues of seven coronary and seven iliac arteries. The m ean interval of the stent deployment to restenosis was 9.1 months for the c oronary artery and 33.7 months for the iliac artery, indicating a 3.7-fold longer interval for the latter. This study does not include cases of acute thrombotic occlusion. The atherectomized tissue from restenotic coronary ar teries showed abundant neointima with alpha-actin-positive and ultrastructu ally synthetic-type smooth muscle cells in a rich myxomatous extracellular matrix. In the iliac arteries, the predominant component of restenosis cons isted of organized thrombi. The neointima of the iliac arteries was mature, and only a small amount of spindle cells were observed in the hyalinized m atrix. The tissue that developed restenosis after stenting was different in the coronary and iliac arteries included in this series. This study on the atherectomized tissue suggests that even in the chronic stage, a major cau se of in-stent restenosis among the larger caliber vessels such as the ilia c artery is not neointima but stent thrombosis.