title: Does clopidogrel increase blood loss following coronary artery bypass surgery?
abstract: BACKGROUND
  Clopidogrel (Plavix) is a potent inhibitor of platelet aggregation used concomitantly with percutaneous coronary interventions and in patients with acute coronary syndromes. Its favorable effects on preventing thrombus formation may have deleterious effects on hemostasis in patients undergoing coronary surgery.
  
  
  METHODS
  Data were collected prospectively on 312 consecutive urgent or emergent coronary artery bypass patients from July 1999 through April 2001 at a tertiary care center. Patients were stratified into three groups: clopidogrel within 4 days of operation (n = 41), clopidogrel continued until 5 to 8 days before operation (n = 39), and clopidogrel discontinued more than 8 days before operation or were never taking clopidogrel (n = 232).
  
  
  RESULTS
  Preoperative and intraoperative characteristics were similar among all groups. Mediastinal and pericardial chest tube losses in the first 24 hours were 1,044 +/- 750 mL in the clopidogrel within 4 days group, 528 +/- 250 mL in the clopidogrel 5 to 8 days group, and 573 +/- 329 mL in the clopidogrel more than 8 days group (p < 0.01). The mean total blood product transfusions were 12.2 +/- 15.4 U, 1.2 +/- 2.0 U, and 2.6 +/- 5.7 U, respectively (p < 0.001). Reoperation for bleeding was noted in 14.6%, 2.6%, and 1.7%, respectively (p = 0.002). The median hospital lengths of stay for the three groups were 9 days, 7 days, and 7 days, respectively (p = 0.018). There were no statistically significant differences in mortality rate, myocardial infarction, stroke, mediastinitis, or postoperative renal failure among the groups. Multivariable analysis revealed that clopidogrel within 0 to 4 days of operation was an independent predictor of transfusion requirements (OR 4.22, 95% confidence interval [CI] 2.07, 9.34, p = 0.001), intensive care unit (ICU) length of stay (OR 3.14, 95% CI 1.40, 7.04, p = 0.006), and total hospital length of stay (coefficient 7.65, se 2.41, p = 0.002).
  
  
  CONCLUSIONS
  Clopidogrel within 4 days of coronary bypass surgery is associated with increased blood losses and reoperation for bleeding and, according to multivariable models, is an independent risk factor for increased transfusion requirements and prolonged ICU and hospital length of stay.
authors.affiliation: Division of Cardiac Surgery, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Michael W A
authors.initials: MW
authors.lastname: Chu
authors.forename: Steve R
authors.initials: SR
authors.lastname: Wilson
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Novick
authors.forename: Larry W
authors.initials: LW
authors.lastname: Stitt
authors.forename: MacKenzie A
authors.initials: MA
authors.lastname: Quantz
mesh_terms: D000368:Aged; D001241:Aspirin / Q000008:administration & dosage / Q000627:therapeutic use; D016063:Blood Loss, Surgical; D001803:Blood Transfusion / Q000706:statistics & numerical data; D000077144:Clopidogrel; D001026:Coronary Artery Bypass; D003422:Critical Care / Q000706:statistics & numerical data; D004334:Drug Administration Schedule; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004630:Emergencies; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D008131:London; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D011183:Postoperative Complications / Q000453:epidemiology; D019106:Postoperative Hemorrhage / Q000139:chemically induced* / Q000209:etiology / Q000601:surgery; D011292:Premedication; D011446:Prospective Studies; D012307:Risk Factors; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin