Dysnatraemia in heart failure

Dysnatraemia in heart failure
Nikolas Deubner1, Dominik Berliner1,2, Anna Frey2, Gülmisal Güder1,2, Susanne Brenner1,2, Wiebke Fenske1,2, Bruno Allolio1,2, Georg Ertl1,2, Christiane E. Angermann1,2 and Stefan Störk1,2,*
+ Author Affiliations
1Department of Internal Medicine I–Cardiology, University Hospital Würzburg, Germany
2Comprehensive Heart Failure Center, University of Würzburg, Germany
↵*Corresponding author. Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, D-97078 Würzburg, Germany. Tel: +49 931 201 46362, Fax: +49 931 201 646362, Email: stoerk_s@klinik.uni-wuerzburg.de
Received January 16, 2012.
Revision received April 15, 2012.
Accepted June 15, 2012.
Abstract

Aims To investigate in detail the correlates of dysnatremia, and to estimate its differential prognostic relevance in patients with heart failure with reduced or preserved LVEF.
Background Hyponatraemia has been shown to carry important prognostic information in patients with heart failure with reduced left ventricular ejection fraction (LVEF). However, exact serum sodium cut-off levels are not defined and the implications for heart failure with preserved ejection fraction (HF-pEF) are unclear. The prognostic value of hypernatraemia has not been investigated systematically. Therefore, the aim of this study was to investigate in detail the correlates of dysnatraemia, and to estimate its differential prognostic relevance in patients with heart failure with reduced or preserved LVEF.
Methods and results One thousand consecutive patients with heart failure of any cause and severity from the Würzburg Interdisciplinary Network for Heart Failure registry were included. Non-linear models for the association between serum sodium and mortality risk were calculated using restricted cubic splines and Cox proportional hazard regression. Median follow-up time for survivors was 5.1 years.
Results Independent correlates of dysnatraemia included guideline-recommended medication for chronic heart failure, indicators of renal function, and reverse associations with established cardiac risk factors. Overall mortality was 56%. Both hyponatraemia (n = 72) and hypernatraemia (n = 98) were associated with a significantly increased mortality risk: hazard ratio (HR) 2.10, 95% confidence interval (CI) 1.60–2.77; and HR 1.91, 95% CI 1.49–2.45, respectively. A U-shaped association of serum sodium with mortality risk was found. Prognosis was best for patients with high normal sodium levels, i.e. 140–145 mmol/L.
Conclusions Both hypo- and hypernatraemia indicate a markedly compromised prognosis in heart failure regardless of LVEF. Sodium levels within the reference range carry differential information on survival, with serum levels of 135–139 mmol/L indicating an increased mortality risk.

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