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©2013 UpToDate ® Print Email ACC/AHA Guideline Summary: Bridging therapy in patients with mechanical valves who require interruption of warfarin therapy for noncardiac surgery, invasive procedures, or dental care Class I - There is evidence and/or general agreement that the following approach to bridging therapy is effective in patients with mechanical valves • Among patients who are at low risk for thrombosis, which is defined as a bileaflet aortic valve with no risk factors*. 1. Warfarin should be withheld 48 to 72 hours before the procedure to allow the INR to fall below 1.5. 2. Warfarin is restarted 24 hours after the procedure. 3. Heparin is usually not necessary. • Among patients who are at high risk for thrombosis, which is defined as a mechanical aortic valve with any risk factor* or any mechanical mitral valve. 1. Warfarin should be withheld more than 72 hours before the procedure. 2. Therapeutic doses of intravenous unfractionated heparin should be started when the INR falls below 2.0 (usually 48 hours before the procedure). 3. Heparin is stopped four to six hours before the procedure. 4. Heparin and warfarin are restarted as soon after surgery as bleeding stability permits. 5. Heparin is discontinued when the INR reaches therapeutic levels. Class IIa - The weight of evidence or opinion is in favor of the usefulness of the following approach to bridging therapy in patients with mechanical valves • The administration of fresh frozen plasma when an emergency procedure is necessary. Fresh frozen plasma is preferred in this setting to high dose vitamin K1. Class IIb - The weight of evidence or opinion is less well established for the following approach to bridging therapy in patients with mechanical valves • Among patients at high risk for thrombosis as defined above, therapeutic doses of unfractionated heparin (15,000 units every 12 hours) or low molecular weight heparin (100 U/kg every 12 hours) during the period when the INR is subtherapeutic. Class III - There is evidence and/or general agreement that the following approach to bridging therapy is NOT useful in patients with mechanical valves • Routine high dose vitamin K1, which can cause a hypercoagulable state. * Risk factors include atrial fibrillation, previous thromboembolism, left ventricular dysfunction, a hypercoagulable state, older generation thrombogenic valves, a mechanical tricuspid valve, or multiple valves.

Class III - There is evidence and/or general agreement that the following approach to bridging therapy is NOT useful in patients with mechanical valves • Routine high dose vitamin K1, which can cause a hypercoagulable state. * Risk factors include atrial fibrillation, previous thromboembolism, left ventricular dysfunction, a hypercoagulable state, older generation thrombogenic valves, a mechanical tricuspid valve, or multiple valves. Data from: Bonow RO, Carabello BA, Chatterjee K, et al. 2008 Focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Circulation 2008; 118:e523.