Serum indoxyl sulfate as a potential biomarker of aortic arterial stiffness in coronary artery disease.

BACKGROUND AND AIMS:Indoxyl sulfate (IS), a dietary tryptophan metabolite, acts as a cardiotoxin and uremic toxin. High IS levels are associated with chronic kidney disease and cardiovascular diseases. This study investigated the association between serum IS levels and aortic arterial stiffness (AAS) in coronary artery disease (CAD) patients. METHODS AND RESULTS:The carotid-femoral pulse wave velocity (cfPWV) was measured by the SphygmoCor system and patients with values of >10 m/s were classified in the AAS group. The baseline characteristics were recorded and measured (including biochemical and clinical data). Serum IS levels were determined using liquid chromatography-mass spectrometry. AAS occurred in 50 (34.7%) of 144 patients with CAD. They were older, had higher IS levels and percentages of diabetes, systolic blood pressure, blood urea nitrogen, and creatinine but lower estimated glomerular filtration rates. The IS level and older age significantly correlated with AAS [odds ratio (OR) = 3.834, p = 0.031; OR = 1.095, p = 0.002, respectively]. Furthermore, the serum IS level (β = 0.167, adjusted R2 change: 0.026, p = 0.027) had a significant positive correlation with cfPWV. CONCLUSIONS:Taken together, higher serum IS levels are potential independent biomarkers for AAS in patients with CAD. Therefore, early checking of serum IS levels may help prevent CAD progression and have clinical implications in the near future.