Impact of Indoxyl Sulfate, a Uremic Toxin, on Non-Culprit Coronary Plaque Composition Assessed on Integrated Backscatter Intravascular Ultrasound

BACKGROUND: Uremic toxin has emerged as an important determinant of cardiovascular risk. The aim of this study was to examine the relationship between serum uremic toxin and coronary plaque composition on integrated backscatter intravascular ultrasound (IB-IVUS). METHODS AND RESULTS: IB-IVUS was performed in 47 patients with planned treatment for angina pectoris. Non-culprit intermediate plaque analyzed in this study had to be >5 mm apart from the intervention site. 3-D IB-IVUS analysis was performed to determine percent lipid volume (LV) and fibrous volume (FV). We also measured serum uremic toxins (indoxyl sulfate [IS], asymmetric dimethylarginine [ADMA], and p-cresol [PC]). Glomerular filtration rate correlated with IS (r=-0.329, P=0.04), but did not correlate with ADMA or PC. Percent LV correlated with IS (r=0.365, P=0.02), but did not correlate with ADMA or PC. Percent FV also correlated with IS (r=-0.356, P=0.03), but did not correlate with ADMA or PC. On multivariate regression, only IS was associated with percent LV (r=0.359, P=0.04) and percent FV (r=-0.305, P=0.04) independently of potentially confounding coronary risk factors. CONCLUSIONS: Among the uremic toxins, serum IS might be a novel useful biomarker to detect and monitor lipid-rich coronary plaque on IB imaging.