Angioscopic Evaluation of Neointimal Coverage of Coronary Stents

Drug-eluting stents (DES) reduce coronary restenosis significantly; however, late stent thrombosis (LST) occurs, which requires long-term antiplatelet therapy. Angioscopic grading of neointimal coverage of coronary stent struts was established, and it was revealed that neointimal formation is incomplete and prevalence of LST is higher in DES when compared to bare-metal stents. It was also observed that the neointima is thicker and LST is less frequent in paclitaxel-eluting and zotarolimus-eluting stents than in sirolimus-eluting stents. Many new stents were devised and they are now under experimental or clinical investigations to overcome the shortcomings of the stents that have been employed clinically. Endothelial cells are highly anti-thrombotic. Neo-endothelial cell damage is considered to be caused by friction between the cells and stent struts due to the thin neointima between them which might act as a cushion. Therefore, development of a DES that causes an appropriate thickness (around 100 μm) of the neointima is a potential option with which to prevent neo-endothelial cell damage and consequent LST while preventing restenosis.