Plasma trimethylamine n-oxide is associated with renal function in patients with heart failure with preserved ejection fraction.

BACKGROUND Heart failure with preserved ejection fraction (HFpEF) is an emerging global health problem with less awareness. Renal dysfunction in HFpEF is associated with worse outcome. However, there is lack of rapid, noninvasive and accurate method for risk stratification in HFpEF and renal dysfunction. This study aimed to explore the utility of plasma trimethylamine n-oxide (TMAO) for evaluation of HFpEF and renal function. METHODS Plasma TMAO levels were measured in total 324 subjects comprising 228 HFpEF patients and 96 healthy controls. RESULTS TMAO levels were significantly elevated in patients with HFpEF compared with controls (12.65(9.32-18.66) μg/l vs 10.85(6.35-15.58) μg/l, p <  0.01). Subjects in higher TMAO tertile group had more incidences of HFpEF ((78.5%) in tertile 3 vs (73.39%) in tertile 2 vs (59.26%) in tertile 1, p <  0.01). TMAO concentrations were inversely correlated with estimated glomerular filtration rate (eGFR) and HFpEF patients with impaired renal function (eGFR < 60 ml/min/1.73 m2) had higher TMAO than those with normal eGFR (≥ 60 ml/min/1.73 m2) (14.18(10.4-23.06) μg/l vs 10.9(7.48-15.47) μg/l, p < 0.01). Increased TMAO levels were independently associated with higher risk of HFpEF (OR = 3.49, 95% CI: 1.23-9.86, p = 0.02) and renal dysfunction (OR = 9.57, 95% CI: 2.11-43.34, p < 0.01) after adjustment for multiple traditional risk factors. Furthermore, TMAO had good performance at distinguishing HFpEF from controls (AUC = 0.63, p < 0.01), and renal dysfunction from normal renal function in HFpEF (AUC = 0.67, p < 0.01). CONCLUSION In this cross-sectional study, HFpEF and renal function were closely related with plasma TMAO levels and TMAO may serve as a diagnostic biomarker for HFpEF and renal function.