title: β-blocker dosage and outcomes after acute coronary syndrome.
abstract: BACKGROUND
  Although β-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose β-blocker.
  
  
  METHODS
  Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose β-blocker dosage and MACE at 0-6 months and 6-24 months.
  
  
  RESULTS
  A total of 5,287 ACS subjects were discharged on β-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the β-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose β-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]).
  
  
  CONCLUSIONS
  In ACS patients, rates of MACE for high-dose and low-dose β-blocker doses are similar. These findings question the importance of achieving a high dose of β-blocker in ACS patients and highlight the need for further investigation of this clinical question.
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT; University of Utah, Division of Internal Medicine, Salt Lake City, UT.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Allen
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT; University of Utah, Division of Internal Medicine, Salt Lake City, UT. Electronic address: Stacey.Knight@imail.org.
authors.forename: Stacey
authors.initials: S
authors.lastname: Knight
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT.
authors.forename: Raymond O
authors.initials: RO
authors.lastname: McCubrey
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT.
authors.forename: Tami
authors.initials: T
authors.lastname: Bair
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT; University of Utah, Division of Internal Medicine, Salt Lake City, UT.
authors.forename: Joseph Brent
authors.initials: JB
authors.lastname: Muhlestein
authors.affiliation: University of Miami, Division of Cardiology, Miami, FL.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Goldberger
authors.affiliation: Intermountain Healthcare, Heart Institute, Murray, UT; University of Utah, Division of Internal Medicine, Salt Lake City, UT.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Anderson
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy*; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000368:Aged; D002423:Cause of Death; D023921:Coronary Stenosis / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009026:Mortality; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000453:epidemiology; D009204:Myocardial Revascularization; D016016:Proportional Hazards Models; D012042:Registries; D020521:Stroke / Q000453:epidemiology*
chemical_list: D000319:Adrenergic beta-Antagonists