Abstract 2826: Endothelial Cells Covering Coronary Stent Struts are Frequently Damaged
Background: It is well known that coronary in-stent thrombosis is not infrequently observed by angioscopy even 6 months after stenting. However, the mechanisms underlying this late in-stent thrmobosis are not well known. Since endothelial cells (ECs) are highly anti-thromboic, there is a possibility that ECs covering stent struts are malfunctioning or damaged.
Aim: To examine by percutaneous angioscopy whether ECs covering coronary stent struts are damaged or not.
Subjects and Methods: Twenty-two patients underwent coronary angioscopy 6 months after stenting with bare metal stents. After routine follow-up angiography, an angioscope tip was located in the stent body. After control observation, 1ml of 2.5% Evans blue dye which is well known to stain selectively the damaged ECs, was injected into the stented segment through the flush channel of the angioscope to observe whether ECs are stained in blue or not.
Results: Before Evans blue injection, stent struts were not seen-througfh in 12 segments of 12 patients and were seen-through or naked in 10 segments of 10 patients. ECs were stained in 1 of former group and 9 of latter group. Staining was localized to ECs just on stent struts in 6 and was diffuse extending to ECs between the struts in 3. Thrombi were observed in 2 of diffusely stained group.
Conclusion: ECs covering bare stent struts are frequently damaged when struts are seen-through probably due to friction between ECs and struts, and thrombosis occurs when damages are extended diffusely. Therefore, appropriate thickening of the subendothelial tissues on struts which act as a cushion may be necessary for prevention of ECs damages and resultant late thrombosis. In this respect, it should also be examined whether ECs covering drug eluting stent struts are damaged or not since late in-stent thrombosis occurs in this category of stents.