Kynurenine levels are elevated in patients with heart failure with reduced ejection fraction or atrial fibrillation undergoing hemodialysis

Cardiovascular disease (CVD) is the leading cause of mortality in patients undergoing hemodialysis (HD). Uremic toxins may play a role in this process. One such toxin is kynurenine, a product of tryptophan metabolism that is not cleared sufficiently by HD. In the present study, serum kynurenine and tryptophan levels were measured using ELISA in 119 patients undergoing HD and 25 healthy subjects. In total, 41 patients had coronary heart disease (CHD), 61 patients had heart failure (HF), 27 patients had HF with reduced ejection fraction (HFrEF) and 33 patients had atrial fibrillation (AF). Factors that may influence kynurenine levels in patients undergoing HD, and the associations between kynurenine and CHD, HF and AF were examined. Compared with the healthy individuals, patients undergoing HD had higher kynurenine levels (7.56 vs. 2.33 µM; P<0.001). In patients undergoing HD, kynurenine negatively correlated with inflammatory markers. Kynurenine levels were significantly higher in patients undergoing HD with HFrEF (8.78 vs. 7.56 µM; P=0.03) and AF (9.15 vs. 7.30 µM; P=0.011). Following adjustment, for every 1 µM increase in serum kynurenine levels, the odds ratios for HFrEF and AF were 1.65 (P=0.008) and 1.37 (P=0.039), respectively. On the whole, the present study demonstrates that in patients undergoing HD, serum kynurenine levels are elevated, and are associated with HFrEF and AF. These findings suggest a potential role for this uremic toxin in the development of these cardiovascular disorders.