Association Between Indoxyl Sulfate and Cardiac Dysfunction and Prognosis in Patients With Dilated Cardiomyopathy

Background: Serum indoxyl sulfate (IS) is a uremic toxin that accelerates the progression of chronic kidney disease (CKD). The aim of this study was to determine whether serum IS is associated with hemodynamic parameters or cardiac events in patients with nonischemic dilated cardiomyopathy (DCM). Methods and Results: The 76 patients with DCM had their serum IS and plasma brain natriuretic peptide (BNP) levels measured, and underwent echocardiographic examination. Mean (+/- standard deviation) left ventricular ejection fraction (LVEF) and BNP levels in the patients were 32.5 +/- 10.7% and 204 +/- 219 pg/ml, respectively. Patients were divided into 2 groups, low IS (<0.9 mu g/ml) and high IS (>= 0.9 mu g/ml), based on the median value of serum IS. Although there were no significant differences in LVEF and BNP between the groups, E/e' was significantly greater in the high IS group than in the low IS group. Furthermore, E/e' was an independent determinant of serum IS level. The risk of a cardiac event was significantly higher in the high IS group than in the low IS group (P=0.014). Moreover, serum IS was a significant predictor of cardiac events even after adjustment for BNP. Conclusions: Cardiac dysfunction is associated with the serum IS level, which might serve as a new prognostic marker in DCM patients with normal renal function or mild to moderate CKD. (Circ J 2013; 77: 390-396)