title: Effect of beta-blockers on the risk of atrial fibrillation in patients with acute myocardial infarction.
abstract: BACKGROUND
  Oral beta-blockers improve the prognosis of patients with acute myocardial infarction, while atrial fibrillation worsens the prognosis of this population. The reduction of atrial fibrillation incidence in patients treated with beta-blockers could at least in part explain the benefits of this drug.
  
  
  OBJECTIVE
  To investigate the effect of beta-blockers on the incidence of atrial fibrillation in patients with acute myocardial infarction.
  
  
  METHODS
  We analyzed 1401 patients with acute myocardial infarction and evaluated the occurrence or absence of atrial fibrillation, the use of oral beta-blockers and mortality during the first 24 hours.
  
  
  RESULTS
  a) The use of beta-blockers was inversely correlated with the presence of atrial fibrillation (rho = 0.004; OR = 0.54). b) Correlations with mortality were as follows: 31.5% in patients with atrial fibrillation, 9.2% in those without atrial fibrillation (rho < 0.001; Odds Ratio = 4.52), and 17.5% in patients not treated with beta-blockers and 6.7% in those who received the drug (rho < 0.001; OR = 0.34). c) Adjusted Models: The presence of atrial fibrillation was independently correlated with mortality (OR = 2.48, rho = 0.002). The use of beta-blockers was inversely and independently correlated with mortality (OR = 0.53; rho = 0.002). The patients who used beta-blockers showed a lower risk of atrial fibrillation (OR = 0.59; rho = 0.029) in the adjusted model.
  
  
  CONCLUSIONS
  The presence of atrial fibrillation and the absence of oral beta-blockers increased in-hospital mortality in patients with acute myocardial infarction. Oral beta-blockers reduced the incidence of atrial fibrillation, which might be at least partially responsible for the drug's benefit.
authors.affiliation: Heart Institute (InCor HCFMUSP), Acute Coronary Care Unit, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - São Paulo/SP, Brazil.
authors.forename: Antonio Eduardo
authors.initials: AE
authors.lastname: Pesaro
authors.forename: Alexandre
authors.initials: A
authors.lastname: de Matos Soeiro
authors.forename: Carlos Vicente
authors.initials: CV
authors.lastname: Serrano
authors.forename: Roberto Rocha
authors.initials: RR
authors.lastname: Giraldez
authors.forename: Renata Teixeira
authors.initials: RT
authors.lastname: Ladeira
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Nicolau
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D004812:Epidemiologic Methods; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000401:mortality; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists