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.