Abstract 14778: Combined Shear Stress-Molecular Imaging for the Evaluation of Early Arterial Healing Responses Following Implantation of Bioresorbable Scaffold With Different Strut Thickness

Introduction and Hypothesis: Arterial healing following stent implantation involves a series of biological reactions such as thrombosis, inflammation, neointimal regeneration. Clinical evidences have shown favorable arterial healing after thin-strut stents, however, there has been a lack of in vivo imaging evidence on how strut thickness affect vascular healing process. We evaluated local endothelial shear stress (ESS) and healing response of a thin-strut bioresorbable scaffold (BRS, 100μm) compared to first-generation 157μm-thickness ABSORB. Methods and Results: BRS and ABSORB were simultaneously implanted in left coronary arteries of the same pigs (n=7). Detailed scaffolded-artery 3D model was reconstructed based on OCT and angiography. Scaffold-related inflammation response was serially assessed by dual-modal OCT-near-infrared fluorescence (OCT-NIRF) molecular imaging using macrophage-mannose receptor-Cy7 as an inflammation-targeting agent. On ESS analysis, regions with athero-prone low ESS were significantly greater in thick-ABSORB compared to BRS. Dual-modal OCT-NIRF imaging visualized arterial inflammation activity at peri-strut regions in vivo (Figure). Based on coregistered ESS-NIRF data, we found a significant inverse correlation was found between ESS and NIRF activity (p<0.0001), suggesting immune-modulating effect of ESS during early stent healing phase. Arterial inflammation, quantified as target-to-background ratio, was significantly lower in thin-strut BRS than ABSORB at 2 weeks (p<0.01). At week 3, unlike ABSORB with residual peri-strut NIRF signals, inflammation activity dissipated significantly in BRS. Ex vivo confocal fluorescence microscopy (Figure) and immunohistochemical analysis well corroborated the findings in vivo . Conclusions: Thin-strut BRS was associated with less inflammation and rapid resolution of inflammation compared to thicker-strut ABSORB. This study provides in vivo imaging insights into how strut thickness affects early arterial healing and the importance of ESS as an inflammatory modulator. Our comprehensive imaging strategy enabling evaluation of complex interplay between scaffold, ESS, and artery is expected to enhance understanding of stent healing.