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This section discusses the importance of anticoagulation therapy for patients with prosthetic valves and examines the current guideline recommendations, current evidence for, and ongoing studies on, the use of NOACs in these patients
Thromboembolism and anticoagulant-related bleeding represent the majority of complications experienced by prosthetic valve recipients.1 The need for chronic anticoagulation therapy as a result of AF accompanying valvular heart disease highlights the importance of optimizing the quality of anticoagulation care to minimize postoperative thromboembolic complications, while maintaining an acceptable risk profile.2
After valve repair with a mechanical or bioprosthetic device, VKA therapy is indicated for the prevention of stroke and systemic embolism; American College of Chest Physicians (ACCP)3 and American College of Cardiology (ACC)/American Heart Association (AHA)4,5 guidelines provide recommendations based on the type and position of valve replacement (summarized in Figure) due to the differing associated risk of thromboembolic events:
Antithrombotic prophylaxis for recipients of prosthetic valves4
To date, only one clinical trial – the phase II RE-ALIGN trial – assessed the performance of an NOAC (dabigatran; N=37) versus warfarin (N=22) in patients with a mechanical heart valve. There was an increased rate of thromboembolic and bleeding complications associated with dabigatran versus warfarin that resulted in the trial being terminated prematurely.6
The role of NOACs in patients with prosthetic valves requires further research; two phase II clinical trials have investigated the efficacy and safety of rivaroxaban for the prevention of major complications in patients undergoing mechanical aortic valve replacement (CATHAR trial; ClinicalTrials.gov NCT02128841) and explored how rivaroxaban compared with VKA therapy in patients with AF with bioprosthetic mitral valves (RIVER trial; ClinicalTrials.gov NCT02303795). The RIVER trial is currently ongoing. However, the CATHAR trial has been terminated due to poor patient recruitment.
Multicentre, open-label, randomized trials investigating the use of NOACs compared with standard treatment strategies in patients after transcatheter aortic valve replacement are currently ongoing. These include the GALILEO trial (ClinicalTrials.gov NCT02556203)7 and the ATLANTIS trial (ClinicalTrials.gov NCT02664649).8 The GALILEO trial, a global trial, comparing rivaroxaban-based antithrombotic therapy to an antiplatelet strategy consisting of ASA and clopidogrel.7 The ATLANTIS trial, a phase IIIb trial, aims to demonstrate the superiority of apixaban compared with VKA or antiplatelet therapy.8