Abstract 14512: Cerebral Microembolization After Bioprosthetic Aortic Valve Replacement: An Open-Label Study of Daily Warfarin+Aspirin Versus Aspirin Alone
Background: No mechanistic data exist as to whether aspirin alone is as effective as daily warfarin+aspirin in preventing cerebral embolization in the early postoperative period after bioprosthetic aortic valve replacement (AVR).
Methods: After Research Ethics Board approval and informed consent, we enrolled 56 patients who underwent bioprosthetic AVR and received, in an open-label daily fashion, either warfarin (target INR: 2.0-2.5) + 81 mg of aspirin (N=28), or 325 mg of aspirin alone (N=28). Cerebral microembolization was quantified at 4 hours (baseline) and at 1 month post surgery, by using 1-hour bilateral counting periods of middle cerebral artery high-intensity transient signals (HITS), phased through breathing sequences of room-air and 100%-oxygen. Platelet-function analysis (PFA) of closure times on collagen with Adenosine-Diphosphate (ADP) and Epinephrine (EPI) were used as markers of platelet-dependent hemostasis. Follow-up to 1 year was 100% complete.
Results: There was no significant difference in baseline demographics or platelet function between groups. There was no mortality, stroke or transient ischemic attack in either group. No significant differences were found in the proportion of patients with HITS among those receiving warfarin+aspirin versus aspirin alone at baseline (73% vs. 82%, respectively; p=0.42), and at 1 month (54% vs. 39%; p=0.28) after AVR. The total HITS counts and PFA-CT on collagen were equivalent at baseline and follow-up.
Conclusions: At 1 month post bioprosthetic AVR, Doppler-detected cerebral microemboli are still identified in 54% of patients receiving warfarin plus aspirin, and in 39% of those on aspirin alone. However, the effects of these 2 regimens on cerebral microembolization rates and on platelet function at 1 month after bioprosthetic AVR are equivalent. Therefore, our data support the premise that aspirin alone may safely be used early after bioprosthetic AVR, in patients at low risk for thromboembolism.
- © 2011 by American Heart Association, Inc.