Prognostic Utility of Indoxyl Sulfate for Patients with Acute Coronary Syndrome

Aim: We investigated whether indoxyl sulfate (IS), a protein-bound uremic toxin, predicts prognosis after acute coronary syndrome (ACS). Methods: Serum IS level was determined prospectively in 98 patients who underwent successful primary percutaneous coronary intervention for ACS. Patients on hemodialysis were excluded. The endpoint of this study was six-month composite events including death, nonfatal myocardial infarction, heart failure requiring hospitalization, and adverse bleeding events. Results: During the mean follow-up period of 168 days, composite events occurred in 13.3% of cases. Serum IS level was significantly higher in subjects who developed composite events than in those without events (0.14 ± 0.11 mg/dl vs. 0.06 ± 0.04 mg/dl; p < 0.001). After adjusting for confounding factors, a Cox proportional hazard analysis revealed that the IS level (hazard ratio (HR): 10.6; 95% confidence interval (CI): 1.63–69.3, p = 0.01), hemoglobin level (HR: 0.61; 95% CI: 0.43–0.87; p < 0.01), and left ventricular ejection fraction (LVEF) (HR: 0.95; 95% CI: 0.91–0.99; p = 0.03) were independent predictive factors of composite events. Furthermore, IS level significantly conferred additional value to the combined established risks of LVEF and hemoglobin level for predicting the incidence of composite events (area under the curve: 0.82 vs. 0.88, p = 0.01; net reclassification improvement: 0.67, p = 0.01; and integrated discrimination improvement: 0.15, p < 0.01). Conclusions: The assessment of serum IS level has prognostic utility for the management of ACS.