Clinical characteristics and 1-year outcome of hyponatremic patients hospitalized for heart failure

INTRODUCTION Previous studies have shown that hyponatremia is associated with unfavorable prognosis in patients with heart failure (HF). However, only few studies aimed at the evaluation of long-term outcome in hyponatremic patients hospitalized for HF.

OBJECTIVES The aim of this study was to assess clinical characteristics and 1-year outcome of patients hospitalized for HF with hyponatremia at hospital admission.

PATIENTS AND METHODS The study included 641 Polish participants of the HF Pilot Survey of the European Society of Cardiology. The primary endpoint was all-cause death at 1 year since index hospitalization. The secondary endpoint was all-cause death or rehospitalization for decompensated HF during a 1-year follow-up. 

RESULTS Hyponatremia occurred in 15.8% of 641 patients. On admission, hyponatremic patients were characterized by a higher New York Heart Association class, lower blood pressure, lower body mass index, and higher creatinine and lower hemoglobin concentrations on admission. Compared with normonatremic individuals, hyponatremic patients were at a higher risk of in-hospital death (1.9% vs 9.9%, P <0.0001), death at 1 year (10.4% vs 31.7%; P <0.0001), and death or rehospitalization at 1 year (35.9% vs 56.5%; P <0.0001). In multivariate analyses, hyponatremia was predictive of both the primary (hazard ratio [HR], 3.07; 95% confidence interval [CI], 1.94–4.87; P <0.0001) and secondary endpoints (HR, 1.71; 95% CI, 1.16–2.52; P = 0.007). Hyponatremia was an independent predictor of the primary endpoint also in a subgroup of 621 patients who survived to hospital discharge (HR , 2.11; 95% CI, 1.15–3.86; P = 0.02).

CONCLUSIONS Hyponatremia is a common finding in patients hospitalized for HF. Even in patients who survive to hospital discharge, hyponatremia on admission remains an independent predictor of death in long-term follow-up.