Influence of shear stress on in-stent restenosis:: In vivo study using 3D reconstruction and computational fluid dynamics

Introduction and objectives. Local factors may influence neointimal proliferation following conventional stent implantation. In this study, the relationship between wall shear stress and luminal loss after coronary stenting was assessed using a combination of angiography, intravascular ultrasound, and computational fluid dynamics. Patients and method. Seven patients with de novo right coronary lesions treated with conventional (i.e., bare metal) stents were included. Realistic three-dimensional geometric reconstructions were generated off line from angiographic and intravascular ultrasound data both immediately after stenting and at 6-month follow-up. A finite-volume model was used to calculate local wall shear stress within the stent and 4 mm proximally and distally to the stent. The mean coronary ostium entry flow velocity was assumed to be 25 cm/s in all cases. Results. The mean neointimal thickness was 0.29 (0.21) mm. In five cases, weak negative correlations between wall shear stress and neointimal thickness were found: maximum r value =-0.34, minimum r value =-0.11 (P <.001). The neointimal thickness in segments in which the level of wall shear stress was in the lowest quartile was greater than that in segments in which it was in highest quartile, at 0.34 (0.21) mm and 0.27 (0.24) mm (P <.001) for quartiles; 1 and 4, respectively. Conclusions. Low wall shear stress after stenting favors neointimal proliferation both within the stent and at the stent's edges.