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| Dabigatran is Effective for Thromboprophylaxis of Mechanical Heart Valves |
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Stephen H. McKellar1, Stuart Abel1, Christopher Camp1, Mark Ereth2, Hartzell V. Schaff1 1Cardiovascular Surgery, Mayo Clinic, Rochester, MN; 2Anesthesia, Mayo Clinic, Rochester, MN Objective: Warfarin reduces the risk of stroke in patients with mechanical heart valves but increases the risk of hemorrhage and is difficult to use. Dabigatran, a new oral direct thrombin inhibitor, has been shown to be effective in reducing the risk of stroke among patients with atrial fibrillation. No such data exists in the setting of mechanical heart valves. We tested the hypothesis that dabigatran is as effective as heparin for thromboprophylaxis of mechanical valves using a porcine heterotopic aortic valve model. Methods: Thirty swine underwent implantation of a modified bileaflet mechanical valved conduit bypassing the ligated, native descending thoracic aorta. Animals were randomized to receive no anticoagulation (AC) (n=10), enoxaparin 2 mg/kg SQ BID (n=10), or dabigatran 20 mg PO BID (n=10). The primary end point was the amount of valve thrombus (mg) at 30 days. Secondary endpoints included quantitative measurement of platelet deposition on the valve prosthesis, thromboelastography (TEG), hemorrhagic and embolic events. Results: At 30 days, we observed a mean of 638±895 mg thrombus for the no AC group, 121±128 mg for the enoxaparin group, and 19±31 mg for the dabigatran group (P=0.01 for enoxaparin vs. dabigatran). Fewer platelets were deposited on the valves from the dabigatran group (2.7x108) compared to the enoxaparin group (1.8x109), (P=0.03). No major or occult hemorrhagic or embolic events were observed. TEG analysis demonstrated that dabigatran produced less prolongation of the K value (P=0.01) and less decrease in the angle (P=0.01) and MA (P=0.001) values compared to enoxaparin. Conclusion: The direct thrombin inhibitor dabigatran is as effective as enoxaparin for short-term thromboprophylaxis of mechanical valves as it best prevented valve thrombus and platelet deposition at 30-days without increased adverse events. The TEG profile of dabigatran is different than that of enoxaparin. These promising results should be tested in long-term animal studies and, if confirmed, should serve as a foundation for prospective clinical trials with dabigatran as an alternative to warfarin in patients with bileaflet mechanical aortic valves. Back to 2010 Annual Meeting Back to Program Outline Back to Main Program |
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