Efficacy and safety of different bridging regimens of parenteral anticoagulation after mechanical valve replacement

Background: Limited evidence exists to guide the use of parenteral anticoagulation in the early postoperative period following mechanical valve replacement (MVR). The purpose of this study was to determine the practice patterns of anticoagulant management in patients undergoing MVR and to compare the 30 day rates of thrombotic and bleeding complications for patients receiving therapeutic vs. non-therapeutic bridging regimens. Methods: We conducted a retrospective chart review of all patients undergoing MVR at five Canadian cardiac surgery centers between January 1, 2003 and December 31, 2010. The primary efficacy outcome was thromboembolism (stroke, transient ischemic attack, systemic embolism or valve thrombosis). The primary safety outcome was major bleeding. Secondary outcomes included venous thromboembolism and death. Treatment effects were assessed using a matched propensity score analysis. Results: We included 1777 patients (mean age 58 years, 40% female) of whom 939 (56%) underwent isolated aortic valve replacement, 578 (34%) isolated mitral valve replacement, and 171 (9%) combined aortic and mitral valve replacement. 944 patients (53%) received therapeutic bridging and 749 patients (42%) received non-therapeutic bridging. Twenty-three patients (2.4%) who received therapeutic bridging versus thirteen patients (1.7%) who received non-therapeutic bridging experienced the primary efficacy outcome (odds ratio [OR] 1.53; 95% confidence interval [CI], 0.65 to 3.59, P=0.33). Fifty-two patients (5.5%) in the therapeutic dosing group vs. twelve patients (1.6%) in the non-therapeutic dosing group experienced the primary safety outcome of major bleeding (OR 4.61; 95% CI, 2.15 to 9.87; P <0.0001). Conclusion: In the early postoperative period following MVR, therapeutic bridging anticoagulation was associated with a similar risk of thromboembolic complications and a significantly increased risk of major bleeding compared to non-therapeutic bridging anticoagulation.