title: A case-cohort study of postoperative myocardial infarction: impact of anemia and cardioprotective medications.
abstract: OBJECTIVE
  Postoperative myocardial infarction (poMI) is a serious and costly complication. Multiple risk factors for poMI are known, but the effect of anemia and cardioprotective medications have not been defined in real-world surgical practice.
  
  
  METHODS
  Patients undergoing inpatient elective surgery were assessed at 17 hospitals from 2008 to 2011 for the occurrence of poMI (American Heart Association definition). Non-MI control patients were chosen randomly on the basis of case type. Descriptive, univariable, and multivariable statistical analysis were performed for primary outcomes of poMI and death at 30 days.
  
  
  RESULTS
  Compared with controls (N = 304), patients with poMI (N = 222) were older (72 ± 11 vs 60 ± 17 years, P < .0001), had a lesser preoperative hematocrit (37 ± 6 vs 39 ± 5, P < .0001), more often were smokers, had a preoperative T-wave abnormality (21% vs 9%, P < .0001), and had a preoperative stress test with a fixed deficit (26% vs 3%; P < .001). Preoperative factors associated with poMI included peripheral vascular disease (odds ratio 2.6; 95% confidence interval 1.3-5.3), tobacco use (1.7; 1.01-2.9), history of percutaneous coronary angioplasty (2.8; 1.6-5.0), and age (1.05; 1.03-1.07), whereas hematocrit >35 (0.51; 0.32-0.82) and preoperative acetylsalicylic acid, ie, aspirin (0.59; 0.4-0.97) were protective. Preoperative β-blockade, statin, and use of angiotensin-converting enzyme inhibitors were not associated with lesser rates of poMI. Non-MI complication rates were 23-fold greater in the poMI group compared with the control group (P < .0001). Mortality with poMI within 30 days was 11% compared with 0.3% in non-MI control patients (P < .0001). In patients with poMI, factors independently associated with death included use of epidurals (3.5; 1.07-11.4) and bleeding (4.2; 1.1-16), whereas preoperative use of aspirin (0.29; 0.1-0.88), and postoperative β-blockade (0.18; 0.05-0.63) were protective. Cardiac catheterization, percutaneous coronary intervention, or coronary artery bypass grafting after poMI was performed in 34% of those alive and 20% of those who died (P = .16).
  
  
  CONCLUSIONS
  In the current era, poMI patients have a markedly increased risk of death. This risk is decreased with preoperative use of acetylsalicylic acid and post MI β-blockade. Further study is warranted to explore the role of anemia and cardiac interventions after poMI.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI. Electronic address: henke@umich.edu.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Henke
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Grettel
authors.initials: G
authors.lastname: Zamora-Berridi
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Englesbe
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Shijie
authors.initials: S
authors.lastname: Cai
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Linda
authors.initials: L
authors.lastname: Brooks
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Ellen
authors.initials: E
authors.lastname: McKeown
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Laurel
authors.initials: L
authors.lastname: Phillips
authors.affiliation: Department of Anesthesia, University of Michigan, Ann Arbor, MI.
authors.forename: Wei
authors.initials: W
authors.lastname: Lau
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Darrell C
authors.initials: DC
authors.lastname: Campbell
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000150:complications*; D001241:Aspirin / Q000627:therapeutic use*; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D011182:Postoperative Care / Q000379:methods; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D002316:Cardiotonic Agents; D001241:Aspirin