Possible Role of Damaged Neoendothelial Cells in the Genesis of Coronary Stent Thrombus in Chronic Phase

Abstract

SummaryThe mechanism(s) underlying formation of coronary stent thrombus (ST) in chronic phase is yet unclear. Endothelial cells are highly antithrombotic, therefore, it is conceivable that neoendothelial cells (NECs) covering stent struts are damaged and cause ST. This study was performed to examine the role of damaged NECs covering coronary stent struts in the genesis of occlusive or nonocclusive ST in chronic phase.(1) Forty-four patients with acute coronary syndrome (17 females and 27 males) underwent dye-staining coronary angioscopy, using Evans blue which selectively stains damaged endothelial cells, 6 months after bare-metal stent (BMS) deployment. Neointimal coverage was classified into not covered (grade 0), covered by a thin layer (grade 1), and buried under neointima (grade 2) groups. (2) In 7 beagles, the relationships between neointimal thickness and ST were examined 6 months after BMS deployment. (3) The NECs on the struts were stained blue in 4 of 25 patients with grade 2 and in 11 of 20 patients with grade 0/1 (P < 0.05). ST was observed in none of the former and in 5 of the latter (P < 0.05). (4) In beagles, neointimal coverage was grade 0/1 when neointimal thickness was 80.2 ± 40.0 μm, whereas grade 2 when thickness was 184 ± 59.4 μm. ST was observed in 9 of 15 struts with neointimal thickness within 100 μm and in one of 17 struts with thickness over 100 μm (P < 0.05). ST arose from damaged NECs covering the stent struts. NECs may have been damaged due to friction between them and struts due to thin interposed neointima which might have acted as a cushion, resulting in ST. (Int Heart J 2011; 52: 12-16)

Bio-tribology of Vascular Devices: A Review of Tissue/Device Friction Research

“…The endothelium tries to repair itself and, in the process, can cover the stent struts [46]. As the new endothelial cells may be damaged, this can lead to the formation of stent thrombi [47]. Once the endothelium is damaged, the aforementioned chain of events leading to restenosis can be activated.…”

Dye-Staining Angioscopy for Coronary Artery Disease

“…In animals, late stent thrombosis occurs when the neointimal thickness is within 100 μm. Neo-ECs may be damaged by friction between them and the stent struts, because of a thin interposed neointima, which should act as a cushion, resulting in late stent thrombosis [15, 16]. These findings suggest the necessity of an appropriate thickness of neointima for prevention of late stent thrombosis.…”

Recent advances in coronary angioscopy

“…LST was observed in grade 0 or 1 group in patients with DES or BMS [10,26,50]. At 6 months after stenting, neoendothelial cells were stained in blue with Evans blue dye which selectively stains damaged endothelial cells when the neointima thickness grade was 0-1 [50,51] (Fig. 11).…”

“…11). In animals, the struts were visible (grade 0 or 1) when the neointimal thickness was around 88 m and LST was frequently observed when the intimal thickness was within 100 m [51]. All these findings indicated that neoendothelial cells were damaged and LST formed on the Determining exactly how to terminate this ''vicious cycle'' is an essential requisite for effective prophylactic treatment of LST.…”