ANTICOAGULATION VERSUS ANTIPLATELET THERAPY IN ADULT PATIENTS UNDERGOING A BIOPROSTHETIC AORTIC VALVE REPLACEMENT: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

Bioprosthetic aortic valve replacement (BAVR) does not mandate lifelong anticoagulation. Whether patients should receive anticoagulation in the early post-operative period is unclear, and guidelines make different recommendations. In this systematic review and meta-analysis, we evaluated the risks and benefits of anticoagulation compared to antiplatelet therapy alone in the early post-operative period after BAVR. We searched Cochrane CENTRAL, MEDLINE, and EMBASE from inception to November 3, 2017 for randomized controlled trials (RCTs) and observational studies comparing anticoagulation and antiplatelet therapy for at least three months after BAVR. Outcomes of interest were mortality, stroke, thromboembolism and bleeding. Title and abstract screening, full-text screening, risk of bias assessment and data collection were performed independently and in duplicate. We evaluated risk of bias for individual studies with the Cochrane tool for RCTs and the CLARITY tools for observational studies. We used the GRADE framework to assess quality of evidence for each outcome. A random-effects model was used to pool the results. Of 2104 references, we reviewed 44 in full text and included seven studies: 2 RCTs and 5 observational, comprising 2309 patients. Bleeding risk was significantly lower in patients receiving antiplatelet therapy in observational studies (RR, 0.34; 95% CI, 0.20-0.58, p=<0.0001, I2=0%, very low quality of evidence), but not in RCTs (RR, 0.34; 95% CI, 0.11-1.04, p= 0.06, I2=0%, low quality of evidence). Mortality did not differ significantly between treatment arms in RCTs (RR 0.82, 95% CI, 0.33-2.03, p=0.84, I2=0%, moderate quality of evidence) or observational studies (RR, 0.47, 95% CI, 0.18-1.22, p=0.11, I2=50%, very low quality of evidence). Stroke risk was not significantly different with anticoagulation compared to antiplatelet therapy in RCTs (RR, 0.90; 95% CI, 0.35-2.33, p=0.83, I2=0%, low quality evidence) or observational studies (RR, 0.57; 95% CI, 0.31-1.03, p=0.06, I2=0%, very low quality evidence). Thromboembolism risk was also not significantly different in both RCT and observational studies (RR, 1.13; 95% CI, 0.51-2.49, p=0.76, I2=0%, moderate quality evidence and RR, 0.71; 95% CI, 0.38-1.32, p=0.43, I2=0%, very low quality evidence, respectively). Our findings suggest that antiplatelet therapy alone in the early period after BAVR is not associated with a significantly higher risk of mortality or stroke when compared with oral anticoagulation. However, antiplatelet therapy may be associated with a significantly lower bleeding risk compared with anticoagulant therapy. Based on these results, antiplatelet therapy may be sufficient for early thromboembolism prophylaxis after BAVR.