Reproducibility of near-infrared spectroscopy for the detection of lipid core coronary plaques and observed changes after coronary stent implantation

Objectives: To evaluate the reproducibility of catheter-based intracoronary near-infrared spectroscopy (NIRS) for the detection of lipid core coronary plaques (LCPs) and to examine stenting-induced changes in NIRS findings. Background: The in-vivo reproducibility of coronary NIRS findings and their changes after stenting have not previously been characterized. Methods: NIRS assessment using an automated pullback catheter was performed in duplicate in 36 vessels in 31 patients. The reproducibility of the Lipid Core Burden Index (LCBI) and the presence and number of LCPs was assessed. The changes in LCBI after stenting were also assessed in 25 vessels in 22 patients. Results: LCBI of the first and second pullback was 64 ± 43 and 70 ± 62, respectively, with excellent correlation (Spearman's rho 0.927, intraclass correlation coefficient 0.925). Depending on LCP definition, mean LCP length, and median LCP number ranged from 2.44 to 17.25 mm, and from 0 to 2, respectively per artery studied. High correlation was observed between the two pullbacks for total LCP length (depending on the LCP definition used, the Spearman's rho and the intraclass correlation coefficient ranged from 0.72 to 0.89, and from 0.76 to 0.91, respectively) and for LCP number (depending on the LCP definition used, the Spearman's rho and the intraclass correlation coefficient ranged from 0.70 to 0.87, and from 0.67 to 0.88, respectively). The mean LCBI decreased by 40% from 78 ± 47 to 48 ± 38 after stenting (P < 0.001). Conclusion: The LCBI and LCP length NIRS measurements have high reproducibility. LCBI significantly decreases after coronary stenting.