Pathophysiology of superficial femoral artery in-stent restenosis.

Peripheral artery disease (PAD) is an emerging problem especially with aging population and increase in the incidence of diabetes and metabolic syndrome. The disease is histologically characterized by the presence of moderate to severe calcification and fibrous plaques as compared to coronary and carotid atherosclerotic disease, which are richer in necrotic core. Endovascular therapy for the superficial femoral artery (SFA), at least in the United States, has been largely limited to balloon angioplasty and stenting and these are considered safe and relatively effective therapies. However, the patency rates remain low even at one year and restenosis is a growing and challenging problem. Recently the development of newer devices, i.e., drug-eluting stent, and drug coated balloon are showing greater efficacy and are being adopted into daily practice. In this review, we will present the morphologic characteristics of the underlying SFA atherosclerotic disease and discuss in-stent restenosis and the mechanisms that may be involved in the induction of excessive smooth muscle cell proliferation and deposition of proteoglycans and collagen, that lead to restenosis.