Early urinary sodium trajectory and risk of adverse outcomes in acute heart failure and renal dysfunction.

Introduction And Objectives: Urinary sodium (UNa) has emerged as a useful biomarker of poor clinical outcomes in acute heart failure (AHF). Here, we sought to evaluate: a) the usefulness of a single early determination of UNa for predicting adverse outcomes in patients with AHF and renal dysfunction, and b) whether the change in UNa at 24hours (ΔUNa24h) adds any additional prognostic information over baseline values.

Methods: This is a post-hoc analysis of a multicenter, open-label, randomized clinical trial (IMPROVE-HF) (ClinicalTrials.gov NCT02643147) that randomized 160 patients with AHF and renal dysfunction on admission to a) the standard diuretic strategy, or b) a carbohydrate antigen 125-guided diuretic strategy. The primary end point was all-cause mortality and total all-cause readmissions.

Results: The mean age was 78±8 years, and the mean glomerular filtration rate was 34.0±8.5mL/min/1.73 m. The median UNa was 90 (65-111) mmol/L. At a median follow-up of 1.73 years [interquartile range, 0.48-2.35], 83 deaths (51.9%) were registered, as well as 263 all-cause readmissions in 110 patients. UNa was independently associated with mortality (HR, 0.75; 95%CI, 0.65-0.87; P <.001) and all-cause readmissions (HR, 0.92; 95%CI, 0.88-0.96; P <.001). The prognostic usefulness of the ΔUNa24h varied according to UNa at admission (P for interaction <.05). The ΔUNa24h was inversely associated with both end points only in the group with UNa ≤ 50 mmol/L. Conversely, no effect was found in the group with UNa> 50 mmol/L.

Conclusions: In patients with AHF and renal dysfunction, a single early determination of UNa ≤ 50 mmol/L identifies patients with a higher risk of all-cause mortality and readmission. The ΔUNa24h adds prognostic information over baseline values only when UNa at admission is ≤ 50 mmol/L.