title: Cerebral microembolization after bioprosthetic aortic valve replacement: comparison of warfarin plus aspirin versus aspirin only.
abstract: BACKGROUND
  No human physiological data exists on whether aspirin only is as effective as warfarin plus aspirin in preventing cerebral microembolization in the early postoperative period after bioprosthetic aortic valve replacement (bAVR).
  
  
  RESULTS
  We prospectively enrolled 56 patients who had no other indication for oral anticoagulation, who underwent bAVR and received, in an open-label fashion, either daily warfarin (for INR 2.0-3.0) plus 81 mg of aspirin (n=28) or 325 mg of aspirin only (n=28). Cerebral microembolization was quantified at 4 hours (baseline) and at 1 month postoperatively, by recording 1-hour bilateral middle cerebral artery (MCA) microembolic signals (MES). Platelet-function analysis (PFA) of closure times (CT) on collagen was also used as a marker of platelet-dependent activation. Follow-up to 1 year was complete. Preoperative demographics and baseline platelet function were equivalent in both groups. There was no mortality, stroke, or transient ischemic attack at 1 year in either group. No significant differences were found in the proportion of patients with MES among those receiving warfarin plus aspirin versus aspirin only, at baseline (68% versus 82%, respectively; P=0.4) and at 1 month (46% versus 43%; P=1.0) after bAVR. The total MES and PFA were also equivalent between groups, at baseline and follow-up.
  
  
  CONCLUSIONS
  Early after bAVR, the effects of these 2 antithrombotic regimens on cerebral microembolization and platelet function are equivalent. These data bring new mechanistic support to the premise that aspirin only may safely be used early after bAVR in patients who have no other indication for oral anticoagulation.
authors.affiliation: Division of Cardiac Surgery, University of Ottawa, Ottawa, Canada.
authors.forename: Talal
authors.initials: T
authors.lastname: Al-Atassi
authors.forename: Khanh
authors.initials: K
authors.lastname: Lam
authors.forename: Melissa
authors.initials: M
authors.lastname: Forgie
authors.forename: Munir
authors.initials: M
authors.lastname: Boodhwani
authors.forename: Fraser
authors.initials: F
authors.lastname: Rubens
authors.forename: Paul
authors.initials: P
authors.lastname: Hendry
authors.forename: Roy
authors.initials: R
authors.lastname: Masters
authors.forename: William
authors.initials: W
authors.lastname: Goldstein
authors.forename: Pierre
authors.initials: P
authors.lastname: Bedard
authors.forename: Thierry
authors.initials: T
authors.lastname: Mesana
authors.forename: Marc
authors.initials: M
authors.lastname: Ruel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001024:Aortic Valve Stenosis / Q000601:surgery; D001241:Aspirin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001705:Bioprosthesis; D003094:Collagen / Q000494:pharmacology; D001026:Coronary Artery Bypass / Q000706:statistics & numerical data; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000096:biosynthesis; D015539:Platelet Activation / Q000187:drug effects; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D019007:P-Selectin; D014859:Warfarin; D003094:Collagen; D001241:Aspirin