Prognostic Impact of Hyponatremia and Hypernatremia at Admission and Discharge in Heart Failure Patients With Preserved, Mid-Range, and Reduced Ejection Fraction

Abstract

Background Hyponatremia is common in patients with acute heart failure (HF). Our aim was to determine the impact of sodium disturbances on mortality and readmissions in HF with reduced left ventricular ejection fraction (HFrEF), preserved ejection fraction (HFpEF), and mid‐range ejection fraction (HFmrEF).

Methods Prospective multicentre consecutive registry in 20 hospitals including patients admitted due to acute HF in cardiology departments. Sodium <135 mmol/L was considered hyponatremia, >145 mmol/L hypernatremia, and 135–145 mmol/L normal.

Results A total of 1309 patients were included. Mean age was 72.0 ± 11.9 years, 810 (61.9%) were male. Mean serum sodium level was 138.6 ± 4.7 mmol/L at hospital admission, and 138.1 ± 4.1 mmol/L at discharge. The evolution of sodium levels was: normal‐at‐admission/normal‐at‐discharge 941 (71.9%), abnormal‐at‐admission/normal‐at‐discharge 127 (9.7%), normal‐at‐admission/abnormal‐at‐discharge 155 (11.8%), and abnormal‐at‐admission/abnormal‐at‐discharge 86 (6.6%). Hyponatremia at discharge was more common in HFrEF (109 (20.7%)) than in HFpEF (79 (13.9%)) and HFmrEF (27 (12%)), P = 0.003. The prevalence of hypernatremia at discharge was similar in the three groups: HFrEF (10 (1.9%)), HFpEF (12 (2.1%)), and HFmrEF (4 (1.9%)), P = 0.96. In multivariate analysis, abnormal sodium concentrations at hospital admission (Hazard Ratio (HR) 1.42, 95% confidence interval (CI) 1.15–1.76, P = 0.001), and discharge (HR 1.33, 95% CI 1.08–1.64, P = 0.007) were both independently associated with increased mortality and readmissions at 12 months.

Conclusions Hyponatremia and hypernatremia at admission and discharge predict a poor outcome in patients with acute HF, regardless of LVEF. Hyponatremia at discharge is more frequent in HFrEF than in the other LVEF groups.