title: Relation between serum sodium levels and prognosis in outpatients with chronic heart failure: neutral effect of treatment with beta-blockers and angiotensin-converting enzyme inhibitors: data from the Italian Network on Congestive Heart Failure (IN-CHF database).
abstract: BACKGROUND
  The predictive role of hyponatremia has been tested in acute and chronic heart failure. Sodium level is inversely related with renin-angiotensin-aldersterone system (RAAS) and sympathetic nervous activity but important issues remain unresolved. Our aim was to define the level of hyponatremia able to predict 1-year outcomes and investigate the relation between sodium levels and mortality and the effect of beta-blockers and angiotensin-converting enzyme (ACE) inhibitors on this relation.
  
  
  METHODS
  We analyzed 4670 patients enrolled in the IN-CHF Italian Registry. We controlled the predictivity of hyponatremia, testing it either as a continuous variable and dividing the study sample into three severity groups: group 1 (≥136  mEq/l; n = 4207), group 2 (131-135  mEq/l; n = 389) and group 3 (≤130  mEq/l; n = 74). The linearity of the relationship between sodium levels and mortality was also tested.
  
  
  RESULTS
  Mild-to-moderate and severe hyponatremia (groups 2 and 3) independently predicted the 1-year mortality. The relation between sodium concentration and death was not linear and a decrease of 1  mEq/l of sodium increased death rate only for values of sodium 142.9  mEq/l or less. This relationship was not modified by beta-blocker and ACE inhibitor therapies.
  
  
  CONCLUSIONS
  Our data confirm the negative prognostic value of hyponatremia, even of moderate degree, independently of the use of recommended treatments for heart failure.
authors.affiliation: Section of Geriatric Cardiology, Department of Heart and Vessels, University School of Medicine, Florence and Careggi Hospital, Italy.
authors.forename: Samuele
authors.initials: S
authors.lastname: Baldasseroni
authors.forename: Renato
authors.initials: R
authors.lastname: Urso
authors.forename: Francesco
authors.initials: F
authors.lastname: Orso
authors.forename: Bianca P
authors.initials: BP
authors.lastname: Bianchini
authors.forename: Emanuele
authors.initials: E
authors.lastname: Carbonieri
authors.forename: Antonio
authors.initials: A
authors.lastname: Cirò
authors.forename: Lucio
authors.initials: L
authors.lastname: Gonzini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Leonardi
authors.forename: Niccolò
authors.initials: N
authors.lastname: Marchionni
authors.forename: Aldo P
authors.initials: AP
authors.lastname: Maggioni
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D000704:Analysis of Variance; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D002908:Chronic Disease; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000401:mortality; D006801:Humans; D007010:Hyponatremia / Q000097:blood* / Q000150:complications / Q000401:mortality; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010045:Outpatients / Q000706:statistics & numerical data*; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D015415:Biomarkers; D012964:Sodium