P5629The effect of strut protrusion on local shear stress and neointimal hyperplasia

Abstract

Abstract Objective To evaluate effect of strut protrusion (SP) on wall shear stress (WSS) and neointimal growth (NG) 1 and 5 year after implantation of Absorb scaffold. Method 8 patients were selected from Absorb Cohort B. After 3-dimensional reconstruction of coronaries, WSS was quantified using Newtonian steady flow simulation (Figure). At 1-year neointimal thickness (NT) was measured by optical coherence tomography and correlated to WSS and SP post-procedure. Results Median SP was 112.9 (90.8, 133.1) μm. A logarithmic (log) inverse relationship between SP and post-procedure WSS (r=−0.425 p<0.001 correlation coefficients range: −0.143 to −0.553) was observed whereas a correlation between baseline log transformed WSS and NT (r=−0.451 p<0.001 correlation coefficients range: −0.140 to −0.662) was documented at 1 year. Mixed effects analysis between baseline log transformed WSS and NT at follow up yielded a slope of 30 μm/ln Pascal (Pa) and a y-intercept of 98 μm. As result of NG, flow area decreased from 6.91 (6.53, 7.48) mm2 post-implantation to 5.65 (5.47, 6.02) mm2 at 1 year (p=0.01) and to 5.75±1.37 mm2 at 5 years (p=0.024). Vessel surface with low WSS (<1 Pa) decreased from post-procedure (42%) to 1 year (35.9%) and 5 years (15.2%) (p-overall<0.0001). Conclusion SP disturbs laminar flow, creates region of low WSS that is mechanistically associated with NG and lumen area reduction. This observation would suggest thin strut with effective embedment would reduce NG and improve WSS towards physiological values.