title: Preoperative anemia does not increase the risks of early surgical revascularization after myocardial infarction.
abstract: BACKGROUND
  Recent clinical studies suggest preoperative anemia may increase mortality and morbidity after cardiac surgery. Anemic patients are potentially even more vulnerable in the setting of a recent myocardial infarction (MI). The objective of this study was to investigate the impact of preoperative anemia on short-term outcomes after coronary bypass surgery in patients with a recent MI.
  
  
  METHODS
  We conducted a retrospective cohort study of 655 patients who underwent an isolated coronary bypass procedure within 21 days of MI, 432 of whom were anemic preoperatively, defined as a hemoglobin less than 13 g/dL for men and less than 12 g/dL for women. The primary outcomes were in-hospital mortality and major adverse events (MAE), which included MI, stroke, and renal failure requiring dialysis.
  
  
  RESULTS
  Before risk adjustment, in-hospital mortality and the incidence of MAE were significantly higher in patients with anemia versus no anemia (mortality, 5.1% versus 1.4%, p = 0.02; MAE, 8.6% versus 3.1%, p = 0.009). After risk adjustment, the association between preoperative anemia and mortality or MAE became insignificant (mortality odds ratio 2.34, 95% confidence interval: 0.56 to 9.87, p = 0.25; MAE odds ratio 1.13, 95% confidence interval: 0.46 to 2.79, p = 0.78). Preoperative hemoglobin, treated as a continuous variable, yielded similar results.
  
  
  CONCLUSIONS
  Preoperative anemia does not directly increase risks of surgical revascularization performed within 21 days of MI.
authors.affiliation: Cardiac Sciences Program, St. Boniface Hospital/I. H. Asper Clinical Research Institute, Winnipeg, Manitoba, Canada.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Brett
authors.initials: B
authors.lastname: Hiebert
authors.forename: Ryan
authors.initials: R
authors.lastname: Zarychanski
authors.forename: Rakesh C
authors.initials: RC
authors.lastname: Arora
mesh_terms: D000368:Aged; D000740:Anemia / Q000150:complications*; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome