title: Primary angioplasty and selection bias inpatients presenting late (>12 h) after onset of chest pain and ST elevation myocardial infarction.
abstract: OBJECTIVE
  This study was designed to compare the in-hospital outcome of patients presenting with >12 h from onset of chest pain and acute ST elevation myocardial infarction (AMI) who received either immediate invasive or conservative therapy.
  
  
  BACKGROUND
  The benefits of fibrinolytic therapy diminish in patients presenting with AMI and onset of chest pain >12 h. Primary angioplasty has been suggested as a possible treatment for such patients, but they have been excluded from most trials of primary angioplasty. It remains unclear if an invasive treatment strategy is beneficial to these patients.
  
  
  METHODS
  Patients presenting with >12 h of chest pain and AMI were identified from the National Registry of Myocardial Infarction 2 database. Patients receiving invasive therapy <6 h after hospital admission were compared with those receiving conservative therapy. Short-term outcomes were compared on the basis of the initial therapy received. To help control for baseline differences in the groups, patients were matched with controls by propensity score methodology.
  
  
  RESULTS
  On preliminary analysis, in-hospital outcome was improved in terms of recurrent ischemia, angina, myocardial infarction and mortality in patients receiving initial invasive therapy (odds ratio [OR] = 0.67; 95% confidence interval [CI] 0.49 to 0.92 for mortality). After matching by propensity score, the mortality benefit persisted on bivariate analysis (3.5% vs. 5.0%, p = 0.036), though on multivariate analysis, only a non-significant but strong trend toward decreased mortality remained (OR = 0.73; 95% CI 0.53 to 1.01).
  
  
  CONCLUSIONS
  Patients receiving early invasive therapy had lower risk features on presentation. Selection bias may play an important role in choosing these patients' course of treatment and their subsequent outcomes. Certain patients presenting with AMI and duration of chest pain >12 h may benefit from early invasive therapy. These patients could be characterized in a randomized trial.
authors.affiliation: Saint John's Cardiovascular Research Center, Division of Cardiology, Harbor-UCLA Medical Center, Torrance, California 90509, USA.
authors.forename: Yaron
authors.initials: Y
authors.lastname: Elad
authors.forename: William J
authors.initials: WJ
authors.lastname: French
authors.forename: David M
authors.initials: DM
authors.lastname: Shavelle
authors.forename: Lori S
authors.initials: LS
authors.lastname: Parsons
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Sada
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Every
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000401:mortality* / Q000628:therapy*; D015906:Angioplasty, Balloon, Coronary; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality* / Q000628:therapy*; D016017:Odds Ratio; D018579:Patient Selection; D012189:Retrospective Studies; D015983:Selection Bias; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D005343:Fibrinolytic Agents