An overview of anticoagulants, antiplatelet agents, and the combination in patients with mechanical heart valves.

Currently, and for the near future, well-managed warfarin appears to be the most effective method to prevent thromboembolism and bleeding in patients with mechanical heart valves. These patients, when in an anticoagulation management service, have 50-90% fewer complications than patients not managed in this way. Further, the complication rate in such settings approximates that in patients with bioprosthetic, tissue valves not receiving anticoagulation. Oral direct thrombin inhibitors are safe and effective in patients with atrial fibrillation, but this is not proven in those with prosthetic heart valves. The idea of using a combination of different antiplatelet agents is attractive on a theoretical basis, but the available data are limited and do not support this approach. Combined aspirin (or another antiplatelet agent) and warfarin has been recommended, but close scrutiny of this combination suggests that it causes more bleeding and may offer no more protection than well-managed warfarin therapy. Recently, interest has been shown in the significance of high-intensity transient signals (HITS), which may represent gaseous or microemboli, and whether therapy to reduce HITS might influence the development of neurological symptoms. However, present data related to HITS are too limited and conflicting to make any firm conclusions.