Impact of pullback speed on evaluation of lipid core plaque using near-infrared spectroscopy-intravascular ultrasound

Near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) can assess the amount of lipid core plaque, and the latest generation catheter allows for imaging at several different pullback speeds. The purpose of this study was to investigate the impact of pullback speed on evaluation of lipid core plaque using the latest generation NIRS-IVUS catheter. Patients with coronary artery disease who underwent coronary angiography or percutaneous coronary intervention with NIRS-IVUS examination at 2 different pullback speeds (0.5 and 2.0 mm/sec) for the same vessel were enrolled. The values of lipid core burden index (LCBI) and maxLCBI4mm were compared between the images recorded with pullback speeds of 0.5 and 2.0 mm/sec, and match or mismatch of the location where maxLCBI4mm was detected was investigated. In a total of 286 NIRS-IVUS image sets, the location of maxLCBI4mm measured at 0.5 and 2.0 mm/sec was mismatched in 81 (28.3%) image sets. In comparison by vessel type, 20.8% were mismatched in LAD, 31.1% in LCx, and 37.8% in RCA (p = 0.023). In 205 image sets with matched maxLCBI4mm location, the maxLCBI4mm value at 2.0 mm/sec was significantly greater compared with that at 0.5 mm/sec (348.0 vs. 302.0 in median, p < 0.001). In a substantial proportion of patients, the location of maxLCBI4mm values measured at 0.5 and 2.0 mm/sec was mismatched. In the image sets with matched maxLCBI4mm location, the maxLCBI4mm value at 2.0 mm/sec was significantly greater compared with that at 0.5 mm/sec. These results should be noted when applying the cut-off values of maxLCBI4mm recorded at 2.0 mm/sec.