Effect of the endothelial shear stress patterns on neointimal proliferation following drug-eluting bioresorbable vascular scaffold implantation: An optical coherence tomography study

Objectives: This study sought to investigate the effect of endothelial shear stress (ESS) on neointimal formation following an Absorb bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) implantation. Background: Cumulative evidence, derived from intravascular ultrasound-based studies, has demonstrated a strong association between local ESS patterns and neointimal formation in bare-metal stents, whereas in drug-eluting stents, there are contradictory data about the effect of ESS on the vessel wall healing process. The effect of ESS on neointimal development following a bioresorbable scaffold implantation remains unclear. Methods: Twelve patients with an obstructive lesion in a relatively straight arterial segment, who were treated with an Absorb BVS and had serial optical coherence tomographic examination at baseline and 1-year follow-up, were included in the current analysis. The optical coherence tomographic data acquired at follow-up were used to reconstruct the scaffolded segment. Blood flow simulation was performed on the luminal surface at baseline defined by the Absorb BVS struts, and the computed ESS was related to the neointima thickness measured at 1-year follow-up. Results: At baseline, the scaffolded segments were exposed to a predominantly low ESS environment (61% of the measured ESS was <1 Pa). At follow-up, the mean neointima thickness was 113 ± 45 μm, whereas the percentage scaffold volume obstruction was 13.1 ± 6.6%. A statistically significant inverse correlation was noted between baseline logarithmic transformed ESS and neointima thickness at 1-year follow-up in all studied segments (correlation coefficient range -0.140 to -0.662). Mixed linear regression analysis between baseline logarithmic transformed ESS and neointima thickness at follow-up yielded a slope of -31 μm/ln(Pa) and a y-intercept of 99 μm. Conclusions: The hemodynamic microenvironment appears to regulate neointimal response following an Absorb BVS implantation. These findings underline the role of the ESS patterns on vessel wall healing and should be taken into consideration in the design of bioresorbable devices.