Abstract 14699: Effect of Shear Stress on Arterial Inflammation and Development of Healed Plaque: A Comprehensive Shear Stress-Molecular Imaging Study Based on a Novel Multispectral Fluorescence Lifetime Imaging Catheter

Abstract

Introduction and Hypothesis: Endothelial shear stress (ESS) is the tangential force produced by luminal blood flow on arterial endothelium. Both high ESS and low ESS are known to have atherogenic effects, however, it remains poorly understood how these different forces influence coronary atherosclerosis. We evaluated the impact of ESS changes on biochemical and phenotypic difference of coronary atheroma, as assessed by a novel dual-modal optical coherence tomography-fluorescence lifetime imaging (OCT-FLIm) in vivo in beating human coronary arteries. Methods and Results: We constructed a fully-integrated OCT and multispectral FLIm system based on a low-profile dual-modal imaging catheter. High-speed OCT-FLIm could be performed safely in patients undergoing coronary revascularization (Pullback speed: 10-20mm/sec). 3D artery model for computational fluid dynamics was reconstructed by fusion of OCT and angiography. We analyzed spatial associations between ESS and multispectral FLIm information: ch.3(542nm) = fibroatheroma with inflammation; ch.1 (390nm) = loose fibrous tissue (healed plaque). OCT-FLIm visualized coronary microstructure clearly and offered correctly-coregistered biochemical readouts of coronary atherosclerotic plaque in vivo in a label-free manner. Fibroatheromas with increased inflammation activity, as assessed by ch.3 FLIm, were found in low ESS area. On the other hands, high ESS area colocalized with regions with increased ch.1 lifetime, a FLIm signature of loose fibrous tissue (healed plaque). Based on a coregistered ESS-FLIm data, we found a statistically significant negative correlation between ESS and ch.3 lifetime (p>0.001) and a positive correlation between ESS and ch.1 lifetime (p>0.001). Conclusions: Low ESS was associated with lipid and macrophage infiltration whereas high ESS was associated with presence of loose fibrous tissue, a histologic marker of recent plaque disruption leading to rapid plaque progression. Our novel imaging strategy enabling comprehensive evaluation of complex interaction between ESS and biochemical phenotype of plaques is expected to enhance understanding of coronary atherosclerosis biology.