Abstract 2551: Correlation Between the Number of Lipid Core Containing Plaques Identified by a Near Infrared Spectroscopy System and Histologic Findings
A catheter-based near infrared spectroscopy (NIRS) system has recently been cleared by the FDA for detection of lipid core containing plaques of interest (LCP) and lipid core burden index (LCBI) in patients undergoing coronary arteriography. NIRS data are plotted as a map (chemogram) of pullback distance versus rotation, with yellow indicating lipid (see below). Analyses for LCP were based on a 2mm block chemogram and LCBI. An algorithm has been developed to perform automated enhancement of the chemogram and facilitate calculation of the number of LCPs (nLCP) in a segment of artery. The goal is to determine if the enhanced algorithm performs as well as the previously validated LCP and LCBI measures, as determined by histology in human coronary autopsy specimens. NIRS data were obtained from 181 segments from 78 hearts and compared with histology at 2 mm intervals. The image analysis was applied to the chemogram and the nLCP calculated. The ROC analysis of the nLCP versus presence of fibroatheroma in each segment yielded an AUC of 0.84 (95% CI 0.77– 0.89). When one or more LCP was detected, 87% sensitivity and 70% specificity were observed for detection of fibroatheroma. The Spearman correlation between nLCP and LCBI was 0.83 (p-value ≤0.0001). The correlation coefficient of nLCP between repeat pullbacks was 0.83 (p-value ≤0.0001). The number of NIRS-detected LCP in chemograms identified with image enhancement correlates well with previously validated measures and the presence of fibroatheroma by histology. This method has the potential to enhance the clinical utility of the chemogram.