Neointimal coverage over coronary stent struts crossing the side branch Ostia.

ecently, the incidence of restenosis after percutaneous coronary intervention has been greatly reduced by the widespread use of drug-eluting stents (DES).1 At the same time, however, safety concerns have been raised regarding the occurrence of late stent thrombosis (LST) after DES implantation.2,3 Although the mechanism of LST has not yet been fully explained, pathological data from a registry totaling 81 human autopsies of DES recipients revealed that the most powerful histological predictor of stent thrombosis was the degree of endothelial coverage, and that the best morphometric predictor of LST was the ratio of uncovered to total stent struts.4 Further, although the cases were collected before the DES era, a pathological analysis examining 13 cases with histological evidence of an acute occlusive or nonocclusive mural thrombus within a coronary stent in place ≥30days showed that stenting across ostia of major arterial branches (5 cases) and exposure to radiation therapy (3 cases) were the most frequent pathological mechanisms of LST.5