title: Inhospital outcome of acute myocardial infarction in patients with prior coronary artery bypass surgery.
abstract: OBJECTIVE
  Our goals were to compare the characteristics of patients with and without prior coronary artery bypass graft (CABG) presenting with acute myocardial infarction (MI) with or without ST elevation/left bundle branch block (LBBB), and to evaluate the effect of ST shift on inhospital mortality.
  
  
  RESULTS
  Using the National Registry of Myocardial Infarction-3 Registry, we identified 112,697 patients with acute MI without exclusion criteria. Of these, 15,936 (14.1%) had prior CABG. Patients with prior CABG had more adverse characteristics and were less likely to have ST elevation/LBBB than patients without prior CABG. The unadjusted mortality for ST elevation/LBBB patients was higher in patients with prior CABG versus without (16.2% vs 14.1%, P =.0001), whereas in patients without ST elevation/LBBB, prior CABG conferred a lower unadjusted mortality versus without (10.1% vs 12.4%, P =.0001). Adjusting for baseline differences, prior CABG was weakly associated with inhospital mortality in ST elevation/LBBB patients (odds ratio [OR], 1.11, 95% CI 1.00-1.23), but not in patients without ST elevation/LBBB (OR 0.99, 95% CI 0.92-1.07).
  
  
  CONCLUSIONS
  Acute MI patients with prior CABG are more likely to present without ST elevation/LBBB than patients without prior CABG. Prior CABG was weakly associated with inhospital mortality in patients with ST elevation/LBBB, but not in patients without these electrocardiographic findings. This suggests the differences in absolute mortality rates between patients presenting with MI with and without a history of prior CABG are largely caused by differences in baseline characteristics and presentation.
authors.affiliation: Mayo Clinic, Rochester, Minn 55905, USA. mathew.verghese@mayo.edu
authors.forename: Verghese
authors.initials: V
authors.lastname: Mathew
authors.forename: Bernard
authors.initials: B
authors.lastname: Gersh
authors.forename: Hal
authors.initials: H
authors.lastname: Barron
authors.forename: Nathan
authors.initials: N
authors.lastname: Every
authors.forename: Alan
authors.initials: A
authors.lastname: Tiefenbrunn
authors.forename: Paul
authors.initials: P
authors.lastname: Frederick
authors.forename: Judith
authors.initials: J
authors.lastname: Malmgren
mesh_terms: D000208:Acute Disease; D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis*; D015897:Comorbidity; D001026:Coronary Artery Bypass / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000706:statistics & numerical data*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality* / Q000601:surgery; D017063:Outcome Assessment, Health Care; D012042:Registries; D014481:United States / Q000453:epidemiology