Why does in-stent restenosis happen?
When a stent is placed in a blood vessel, new tissue grows inside the stent, covering the struts of the stent. Initially, this new tissue consists of healthy cells from the lining of the arterial wall (endothelium). This is a favorable effect because development of normal lining over the stent allows blood to flow smoothly over the stented area without clotting. Later, scar tissue may form underneath the new healthy lining. In about 25% of patients, the growth of scar tissue underneath the lining of the artery may be so thick that it can obstruct the blood flow and produce an important blockage. In-stent restenosis is typically seen 3 to 6 months after the procedure; after 12 months have passed uneventfully, it is rare. Who is at high risk for in-stent restenosis? Patients with diabetes are at increased risk for in-stent restenosis. Further important risk factors relate to the properties of the blocked artery and the pattern of scar tissue growth inside the artery; the more extensive t
