title: Serum potassium levels and mortality in acute myocardial infarction.
abstract: BACKGROUND
  Clinical practice guidelines recommend maintaining serum potassium levels between 4.0 and 5.0 mEq/L in patients with acute myocardial infarction (AMI). These guidelines are based on small studies that associated low potassium levels with ventricular arrhythmias in the pre-β-blocker and prereperfusion era. Current studies examining the relationship between potassium levels and mortality in AMI patients are lacking.
  
  
  OBJECTIVE
  To determine the relationship between serum potassium levels and in-hospital mortality in AMI patients in the era of β-blocker and reperfusion therapy.
  
  
  METHODS
  Retrospective cohort study using the Cerner Health Facts database, which included 38,689 patients with biomarker-confirmed AMI, admitted to 67 US hospitals between January 1, 2000, and December 31, 2008. All patients had in-hospital serum potassium measurements and were categorized by mean postadmission serum potassium level (<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 4.5-<5.0, 5.0-<5.5, and ≥5.5 mEq/L). Hierarchical logistic regression was used to determine the association between potassium levels and outcomes after adjusting for patient- and hospital-level factors.
  
  
  METHODS
  All-cause in-hospital mortality and the composite of ventricular fibrillation or cardiac arrest.
  
  
  RESULTS
  There was a U-shaped relationship between mean postadmission serum potassium level and in-hospital mortality that persisted after multivariable adjustment. Compared with the reference group of 3.5 to less than 4.0 mEq/L (mortality rate, 4.8%; 95% CI, 4.4%-5.2%), mortality was comparable for mean postadmission potassium of 4.0 to less than 4.5 mEq/L (5.0%; 95% CI, 4.7%-5.3%), multivariable-adjusted odds ratio (OR), 1.19 (95% CI, 1.04-1.36). Mortality was twice as great for potassium of 4.5 to less than 5.0 mEq/L (10.0%; 95% CI, 9.1%-10.9%; multivariable-adjusted OR, 1.99; 95% CI, 1.68-2.36), and even greater for higher potassium strata. Similarly, mortality rates were higher for potassium levels of less than 3.5 mEq/L. In contrast, rates of ventricular fibrillation or cardiac arrest were higher only among patients with potassium levels of less than 3.0 mEq/L and at levels of 5.0 mEq/L or greater.
  
  
  CONCLUSIONS
  Among inpatients with AMI, the lowest mortality was observed in those with postadmission serum potassium levels between 3.5 and <4.5 mEq/L compared with those who had higher or lower potassium levels.
authors.affiliation: Department of Medicine, Emory School of Medicine, Atlanta, GA 30322, USA. agoyal4@emory.edu
authors.forename: Abhinav
authors.initials: A
authors.lastname: Goyal
authors.forename: John A
authors.initials: JA
authors.lastname: Spertus
authors.forename: Kensey
authors.initials: K
authors.lastname: Gosch
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Venkitachalam
authors.forename: Philip G
authors.initials: PG
authors.lastname: Jones
authors.forename: Greet
authors.initials: G
authors.lastname: Van den Berghe
authors.forename: Mikhail
authors.initials: M
authors.lastname: Kosiborod
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006323:Heart Arrest / Q000453:epidemiology; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000401:mortality*; D016017:Odds Ratio; D011188:Potassium / Q000097:blood*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000453:epidemiology
chemical_list: D011188:Potassium