Abstract 18666: What are Key Factors to Achieve Better Stent Apposition at Left Main Bifurcation by Culottes Stenting Technique? Micro-CT Analysis Using Bifurcated Elastic Coronary Artery Models

Abstract

Introduction: We hypothesize that restenosis or stent thrombosis at left main (LM) bifurcation after two-stenting are caused by incomplete stent apposition to coronary artery which may be affected by bifurcation angles, stent design, stent size, and stenting techniques. We investigated influences of those factors on stent apposition using bifurcated elastic coronary artery models (CAMs) to understand better two-stenting with culottes technique. Methods: Based on CT angiography of 209 patients, three LM bifurcated CAMs were manufactured. Focusing on magnitude of the angles between LMT and LCx, the angle data were divided into three groups. Each average model such as the LMT-LCx, LAD-LCx, and LMT-LAD angles of 143°, 59.1°, and 144.3° (mild model: MiM), 121.9°, 70.6°, and 141.4° (moderate model: MoM), and 99.1°, 86.2°, and 143.6° (severe model: SM) was manufactured. Each model has 60% stenosis along with LMT to LAD, and 50% stenosis at LCx ostium. Diameters of LMT, LAD, and LCx were 4.5mm, 3.5mm, and 3.0mm. Two-link Nobori (N) and 3-link Xience V (X) stent were employed for comparison. Moreover, differences in selection of 3.5mm-diameter (3.5D) or 3.0D stent for LCx on stent apposition were investigated, because stent expansion capability differs between the two sizes. When 3.5D stents were used for LCx, stents were deployed at balloon inflation pressure of 4atm for N and 5 or 6atm for X, respectively. Then, additional stent expansion with a 3D balloon was performed. Culottes stenting and final kissing balloon inflation were performed by a single doctor. Stent incomplete apposition volume (SIAV) was quantitatively assessed using micro-CT. Results: When 3D stents were used for LCx, there were no differences in SIAV among MiM, MoM, and SM, both for N and X. Interestingly, when 3.5D stents were used for LCx, SIAV of N were smaller in SM than that in MiM and MoM, respectively (p<0.05), and SIAV of X in SM were larger than that in MiM (p<0.05). When 3D stents were used for LCx, SIAV were comparable between N and X, regardless of the bifurcation angles. When 3.5D stents were used for LCx, SIAV of N were smaller than that of X in MoM and SM (p<0.05). Conclusions: The bifurcation angle between LMT and LCx, stent design, and stent size for LCx were key factors to reduce SIAV in culottes stenting.