Hyponatremia is associated with increased mortality in patients with acute decompensated hear failure

Introduction

Hyponatremia has been identified as a risk factor for increased morbidity and mortality in patients with chronic heart failure (HF) but there are few data for its prevalence and clinical implication in patients with acute decompensated HF.

Methods

One hundred and eighty-two patients (142 male, age 72.1 ± 11.6 years) presented as worsening HF, NYHA III to IV, 48% with ejection fraction ≤ 30%, 43% of ischemic etiology, were enrolled during the period from August 2007 to July 2008. In a retrospective analysis we investigated the relationship between hyponatremia and inhospital mortality, 60-day mortality and 60-day rehospitalization. We divided the patients into three groups according to their admission serum sodium. Group A, Na ≥ 136 mEq/l. Group B, Na = 135 to 131 mEq/l. Group C, Na ≤ 130 mEq/l.

Results

Patients in Group C had a more severe heart failure, lower blood pressure, lower ejection fraction and increased mortality (6.4% in Group C vs. 3.4% in B vs. 1.8% in A, P < 0.05 for inhospital mortality), (13.7% in Group C vs. 7.2% in B vs. 4.7% in A, P < 0.05 for 60-day mortality), (39.3% in Group C vs. 29.1% in B vs. 27.2% in A, P < 0.05 for rehospitalization). In multivariable analysis, either moderate hyponatremia (Group B) or severe hyponatremia (Group C) still remained predictors of death. Group B: hazard ratio = 1.72 95% CI = 1.40 to 2.17. Group C: hazard ratio = 2.88 95% CI = 1.97 to 3.1.

Conclusion

Our data confirm the independent prognostic value of hyponatremia, even moderate, in patients with acute decompensated HF. Serum sodium on admission is an important predictor of increased mortality and rehospitalization.