Plasma Indoxyl sulfate and estimated Glomerular filtration rate - Association with long-term clinical outcome in patients with coronary artery disease-

Background: Indoxyl sulfate (IS), a uremic toxin, has cardiovascular as well as uremic toxicity. We evaluated the prognostic value of blood IS level for long-term outcome.

Methods and Results: This study followed 311 patients with coronary artery disease. Plasma IS level and estimated glomerular filtration rate (eGFR) were determined. The endpoint was a major adverse cardiac event (MACE). Median follow-up was 759 days. IS was significantly higher in patients with MACE than in those without (P<0.001). Patients were divided according to quartiles (Q) of plasma IS level (Q1, Q2, Q3, and Q4). On Kaplan-Meier analysis a significantly lower MACE-free rate was obtained for Q4 compared with the other quartiles (P<0.001). In patients with eGFR ≥90, 89-60, 59-30, 29-15, and <15 ml・min^-1・1.73 m^-2, the percentage of patients in Q4 was 0%, 13%, 29%, 100%, and 100%, respectively. In patients with eGFR 89-60 ml・min^-1・1.73 m^-2, there was no significant difference in MACE-free rate between Q4 and the other quartiles; in patients with eGFR 59-30 ml ・ min^-1・1.73 m^-2, a significantly lower MACE-free rate was obtained for Q4 compared with the other quartiles (P=0.832 and P=0.015, respectively).

Conclusions: Plasma IS level is a significant predictor of MACE, especially in patients with eGFR 59-30 ml ・ min^-11.73 m^-2.