Community acquired versus hospital acquired hyponatremia in acute heart failure: Association with clinical characteristics and outcomes.
Hyponatremia is the commonest electrolyte abnormality in patients hospitalized with heart failure (HF) [1] with a prevalence of 19%–25% [2–4]. It is a result of either increased neurohormonal activation that reflects the severity of HF [5] or due to effect of diuretics. Admission hyponatremia in acute HF is a poor prognostic indicator associated with prolonged hospital stay, higher rates of rehospitalization [6–8], and higher short and long term mortality [2,4,9]. There is scant data that compares community acquired hyponatremia (CAH) and hospital acquired hyponatremia (HAH) in HF. Shchekochikhin and colleagues showed that HAH is also associatedwith increased in-hospitalmortality and length of stay similar to what have been described with CAH [10]. However, no study examined intermediate-term post-discharge outcomes. We hypothesized that HAH has favorable post-discharge outcome compared with CAH in HF. In this analysis we compared the characteristics and intermediate-term outcomes of patients with acute systolic HF with either CAH or HAH. The study is an analysis from the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial. Briefly, the ESCAPE trial is a National Heart, Lung and Blood Institute (NHLBI)-sponsored multicenter study that randomized 433 patients with acute systolic HF to clinical assessment alone versus clinical assessment guided by pulmonary artery catheterization (PAC). The study showed that the PAC did not improve or worsen HF outcomes. Design, rationale, and results of the ESCAPE trial have been previously published [11,12]. Sodium level was measured at multiple time points including hospital admission and discharge. We defined CAH as a serum sodium