Low Serum Sodium as a Poor Prognostic Indicator for Mortality in Congestive Heart Failure Patients

Background The incidence of congestive heart failure (CHF) has not significantly declined over the past 50 years, and overall survival rates are low at 5 years following diagnosis. Numerous studies have shown low serum sodium to be a poor prognostic indicator of all cause mortality in CHF patients. Hypothesis The goal of this hypothesis was to validate if hyponatremia is an important predictor of mortality in an outpatient population of CHF patients on maximal combined angiotensin‐converting enzyme inhibitor (ACEI) and β‐blocker therapy. Methods A total of 364 (13% with hyponatremia) patients with CHF (ejection fraction [EF] ≤ 40%) were enrolled in a heart failure disease management program. The mean New York Heart Association (NYHA) class was II.XII. The average baseline serum sodium was 138.2 mEq/L. Results We evaluated the relationship between hyponatremia (<135 mEq/L) and all‐cause mortality at 40 months. During follow‐up, 8 patients in the hyponatremia group compared to 31 in the normonatremic group died. Results of Kaplan‐Meier analyses indicated there were no significant differences in mortality between the hyponatremia and normonatremic groups (log‐rank test = 0.39). Results for Cox proportional hazards models indicated low sodium was not a significant predictor of mortality (unadjusted odds ratio [OR]: 1.41, 95% confidence interval [CI]: 0.65, 3.07; adjusted OR: 1.60, 95% CI: 0.57, 4.53). Conclusions The relationship between hyponatremia and all‐cause mortality did not reach significance. Hyponatremia did not significantly predict mortality in a CHF population on maximal medical therapy. Copyright © 2010 Wiley Periodicals, Inc.