Objective: To investigate the prevalence and prognostic value of hyponatremia on admission in hospitalized patients for heart failure (HF) from the first HF management center in China.
Methods: Consecutive adult (age of 18 years or older) symptomatic HF patients (NYHA functional class II-IV) admitted between March 2009 and March 2012 in our center were included in the present analysis. Hyponatremia was defined as a serum sodium level < 135 mmol/L. Association between hyponatremia on admission and in-hospital mortality as well as all-cause death and heart failure death during 1-year follow-up after discharge was analyzed.
Results: A total of 1 048 hospitalized patients for HF with complete baseline data were enrolled and the prevalence of hyponatremia on admission was 9.2% (96/1 048). Blood pressure was significantly lower while NYHA functional class and N-terminal pro-B type natriuretic peptide levels were significantly higher in hyponatremic patients than non-hyponatremic patients (all P < 0.05). Kaplan-Meier survival analysis showed that patients with hyponatremia on admission had significant higher in-hospital mortality (P < 0.01), all-cause death rate (P < 0.01) and HF death rate (P < 0.01) during 1-year follow-up post discharge compared with non-hyponatremic patients with. Multiple Cox proportional hazard analysis showed that hyponatremia on admission remained as independent predictor for all-cause death (hazard risk (HR) = 2.105, 95% confidence interval (CI) 1.460-3.036, P < 0.01) and HF death (HR = 2.458, 95% CI: 1.704-3.545, P < 0.01) after adjustment for other covariates.
Conclusion: Hyponatremia is relatively common in patients hospitalized with HF in China and hyponatremia on admission is associated with higher in-hospital mortality and all-cause death and HF death one year after discharge.