Drug-Eluting Stent - Importance of Clinico-Pathological Correlations

The benefit of drug-eluting stents (DES) is the remarkable reduction in the rates of both restenosis and target lesion revascularization. However, the risk of thrombotic complications extends further in DES-implanted arteries compared with those treated with bare-metal stents (BMS). Moreover, in-stent thrombosis (IST) and delayed arterial healing in DES-treated arteries have been identified by histological examination. At autopsy, proliferation of a monolayer composed of endothelium-like cells over stent struts in DES receiving arteries has been observed; however, these cells are negative for well-accepted endothelial cell markers. An inflammatory reaction against the stent struts is apparent after implantation of BMS and paclitaxel-eluting stents, whereas after sirolimus-eluting stents (SES), minimal inflammation is seen up to 6 months after device implantation. IST and in-stent restenosis, both possibly related to a hypersensitivity phenomena, are peculiar to DES, albeit relatively infrequent. A case of enhanced neointimal hyperplasia at 6 months after SES implantation with massive inflammatory reaction including eosinophils, and fibrin deposition is reported here. Observation of the morphological alterations after DES implantation by imaging techniques may furnish important information, but lack of precise comparative data between vascular imaging and histopathology leads to improper interpretation of imaging. Ex vivo imaging using angioscopy, intravascular ultrasound, and optical coherency tomography of SES implantation is presented and the images are compared with the corresponding pathological section. (Circ J 2011; 75: 1548-1558)