Abstract 12673: Placement of Proximal Edge on TCFA and Calcification Correlates With Inadequate Neointimal Coverage of Struts After Drug Eluting Stent Implantation

Abstract

Introduction: Inadequate neointimal coverage of the stent struts is one of the risks for late stent thrombosis, especially in DES. Using OCT, we studied the morphological characteristics of coronary segment of both proximal and distal edges, and evaluated their influence on the neointimal coverage of the strut in chronic phase. Methods: Of 111 culprit coronary lesions in 91 patients, baseline OCT tissue characteristics were evaluated at both proximal and distal edges after DES implantation. The second OCT examination was performed on 9.1 months after implantation, and neointimal coverage of struts was assessed within 5mm inner segments from each stent edge. An uncovered strut was defined as having the signal thickness less than 30 μm from the center of strut. Results: Of 10995 apposed stent struts, uncovered struts were detected in 5.3% within distal and 6.8% within proximal edges. For further statistical analysis, edge segments were classified into two categories according to the ratio of uncovered struts, as the poorly-covered group (highest quartile with % uncovered struts), and the well-covered group (the remaining lower quartiles with % uncovered struts). As to OCT tissue characteristic, 1) fibrous plaque was significantly less observed in the poorly-covered group at both distal and proximal edges (p=0.0031 and p=0.0046, respectively). 2) Lipid pool was more frequently observed in the poorly-covered group than the well-covered group at both distal and proximal edges (p=0.0037 and p=0.0061, respectively). 3) Thin-cap fibroatheroma (TCFA) and calcification were also more frequently observed in the poorly-covered group than the well-covered group (p=0.0025 and p=0.0070, respectively) at proximal stent edge. Logistic regression analysis revealed that existence of calcification at proximal edge was an independent predictor for uncovered struts (OR: 5.48, 95%CI: 1.46-23.46, p=0.0119). TCFA at proximal edge was also an independent predictor (p=0.0044). Conclusions: TCFA and calcification at proximal edge were predictors of uncovered struts. Although mechanism should be further elucidated, placement of proximal edge on such tissue characteristics should be avoided.