Cardiology Letters 2012, 21(1):13-20

Hyponatremia - available and reliable risk predictor in acute heart failure patients.

Varga I¹, Lesný P¹, Líška B², Solík P¹, Luknár M¹, Gonçalvesová E¹

¹ Oddelenie zlyhávania a transplantácie srdca

² Oddelenie intervenčnej kardiológie Národný ústav srdcových a cievnych chorôb, a. s. v Bratislave, Slovenská republika

Purpose: To identify the value of hyponatremia as an in-hospital mortality predictor and its relation to selected characteristics in a general population of hospitalized AHF patients.

Methods: We used the data from SLOVASeZ (Slovak Acute Heart Failure Survey), a nationwide multicenter AHF survey, with 860 consecutive patients enrolled during 3 months in 11 hospitals throughout Slovakia. Hyponatremia was defined as serum sodium < 135 mmol/l at admission. We analysed fifty-seven variables in relation to clinical manifestation, diagnostics and treatment of AHF in univariate analysis. Significant variables (p < 0.05) were subsequently entered into a linear regression model for multivariate analysis.

Results: Hyponatremia was present in 118 patients (14%). Patients with hyponatremia had higher in-hospital mortality (20.0 vs. 6.3%, p = 0,006) and hyponatremia was also an independent predictor of in-hospital mortality (p < 0.05). Twenty-four significant parameters associated with hyponatremia were identified in univariate analysis. Hyponatremia was significantly more common in patients admitted repeatedly due to heart failure (HF), in NYHA class III/IV, due to acute decompensation of chronic HF, hypotension (systolic blood pressure < 100 mmHg), with jugular venous distension and hepatomegaly. Hyponatremia was also more frequent in patients with atrial fibrillation/flutter and QRS complex duration > 120 ms, left ventricular ejection fraction < 30%, anemia (according to WHO criteria), elevated blood urea nitrogen (> 8.5 mmol/L), creatinine > 170 umol/L, hyperbilirubinemia (> 25 umol/L) and dyskaliemia (< 3.5 mmol/L or > 5.0 mmol/L) at admission. Hyponatremia was more common in patients acutely treated with inotropes/vasopressors, and with furosemide at discharge. Hyponatremia was less frequent in patients treated with angiotensin-converting enzyme inhibitors and/or angiotensin II receptor blockers, beta-blockers, slow-realease nitrates or statins. Parameters independently associated with hyponatremia according to previously defined criteria were acute decompensation of chronic heart failure as cause of admission, hypotension, hyperbilirubinemia and usage of inotropes/vasopressors (p < 0.05 for all).

Conclusion: Hyponatremia is a frequent and simply identifiable finding in AHF patients. It is a reliable and independent predictor of in-hospital mortality. Hyponatremia is associated with acute worsening of chronic heart failure, hypotension, hyperbilirubinemia and usage of inotropes/vasopressors which makes it a useful parameter in detection of advanced hypoperfusion and therefore of worse prognosis of hyponatremic patients. Moreover, hyponatremia is recently perceived as a potential therapeutic target.

Keywords: acute heart failure; hyponatremia; prognosis; therapy

Published: January 1, 2012  Show citation