Abstract 16300: Efficacy and Safety of Anticoagulation Following Bioprosthetic Aortic Valve Replacement: A Meta-analysis

Abstract

Background: The American College of Cardiology (ACC) guidelines recommend three months of anticoagulation (AC) after replacement of the aortic valve with a bioprosthesis (BP). However, there remains great variability in the current clinical practice and conflicting results from clinical studies. To assist clinical decision making, we pooled the existing evidence to assess whether AC in the setting of a new BP was associated with improved outcomes and/or greater risk of bleeding. Methods: We searched the PubMed database from the inception of these databases until April 2015 to identify original studies (observational studies or clinical trials) that assessed AC with warfarin in comparison with either aspirin or no antiplatelet or anticoagulant therapy. We included the studies if their outcomes included thromboembolism or stroke/transient ischemic attacks (TIA) and bleeding events. Quality assessment was performed in accordance with the Newland Ottawa scale and random effects was used to pool the data from the available studies. I2 testing was done to assess the heterogeneity of the included studies. Results: After screening through 170 papers, a total of 13 studies (cases=6431, controls=18210) were included in the final analyses. Use of warfarin use was associated with a significantly increased risk of overall bleeding (OR= 1.96, 95% CI 1.25-3.08, P<0.0001) or bleeding risk at 3 months (OR= 1.92, 95% CI 1.10-3.34), P<0.0001) compared with aspirin or placebo. With regard to composite primary outcome variables (risk of venous thromboembolism, stroke or TIA) at 3 months, no significant difference was seen with warfarin (OR= 1.13, 95% CI 0.82-1.56, P=0.67). Moreover AC was also not shown to improve outcomes at time interval >3 months (OR= 1.12, 95% CI 0.80-1.58, P=0.79). Conclusion: Contrary to the current guidelines, a meta-analysis of prior studies suggests that AC in the setting of an aortic bioprosthesis significantly increases bleeding risk without a favorable impact on thromboembolic events. Larger, randomized controlled studies should be performed to further guide this clinical practice.