title: A population-based analysis of the class effect of beta-blockers after myocardial infarction.
abstract: BACKGROUND
  Long-term treatment with beta-blockers reduces mortality after acute myocardial infarction (AMI). Whether beta-blockers exert a class effect is unknown.
  
  
  METHODS
  We analyzed mortality after AMI in Canadian patients 65 years or older who were discharged from hospital with a diagnosis of AMI from April 1996 to March 2000. Administrative data from Quebec, Ontario, and British Columbia were merged. We compared patients prescribed with metoprolol, acebutolol, or atenolol within 90 days after discharge.
  
  
  RESULTS
  Among 31576 patients, 67% were prescribed with metoprolol, 24% with atenolol, and 9% with acebutolol. Clinical characteristics and proportion of days covered with a beta-blocker prescription were similar across groups. Although controlling for time-dependent covariates representing current use and dosage, as well as for age, sex, congestive heart failure, and several other comorbidities, patients who filled a prescription for acebutolol (hazard ratio 0.71, 95% CI 0.62-0.81) or atenolol (hazard ratio 0.79, 95% CI 0.73-0.87) had significantly lower mortality in comparison with metoprolol.
  
  
  CONCLUSIONS
  The higher mortality observed in patients receiving metoprolol compared with those receiving atenolol or acebutolol challenges the concept of a class effect of beta-blockers for secondary prevention of AMI.
authors.affiliation: Division of Cardiology, Department of Medicine, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rinfret
authors.forename: Michal
authors.initials: M
authors.lastname: Abrahamowicz
authors.forename: Jack
authors.initials: J
authors.lastname: Tu
authors.forename: Karin
authors.initials: K
authors.lastname: Humphries
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Eisenberg
authors.forename: Hugues
authors.initials: H
authors.lastname: Richard
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.forename: Louise
authors.initials: L
authors.lastname: Pilote
mesh_terms: D000070:Acebutolol / Q000627:therapeutic use*; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D001262:Atenolol / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use*; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000401:mortality*
chemical_list: D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D000070:Acebutolol; D008790:Metoprolol