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©2013 UpToDate ® Print Email ACC/AHA guideline summary: Anticoagulation regimen in pregnant women with mechanical prosthetic heart valves Class I - There is evidence and/or general agreement that the following approaches to anticoagulation therapy are indicated in pregnant women with mechanical prosthetic heart valves: • For women who are attempting to become pregnant, anticoagulation options during pregnancy are discussed so that anticoagulation can be uninterrupted once pregnancy is achieved. Because of the risk of warfarin embryopathy between 6 and 12 weeks of gestation, pregnancy tests should be monitored. • During pregnancy, continuous therapeutic anticoagulation with frequent monitoring. • Women who elect to stop warfarin between 6 and 12 weeks of gestation should be treated with dose-adjusted continuous intravenous unfractionated heparin (UFH), subcutaneous UFH, or low molecular weight heparin (LMWH). • Between 12 and 36 weeks, the patient can be treated with dose-adjusted continuous intravenous UFH, subcutaneous UFH, or LMWH, or warfarin. With warfarin compared to the different heparin regimens, the fetal risk is higher but the maternal risk appears to be lower for prosthetic valve thrombosis and systemic embolization. Heparin therapy, particularly UFH, also carries the risks of heparin-induced thrombocytopenia and osteoporosis. 1. Dose-adjusted LMWH should be given twice daily subcutaneously to maintain the anti-Xa level between 0.7 and 1.2 U/mL at four hours after dosing. LMWH should NOT be given if such monitoring cannot be performed. 2. With dose-adjusted UFH, the aPTT should be at least twice control. 3. With warfarin, the goal INR is 3.0 (range 2.5 to 3.5). Warfarin should be discontinued and continuous intravenous UFH started beginning two to three weeks before planned delivery. Class IIa - The weight of evidence or opinion is in favor of the usefulness of the the following approaches to anticoagulation therapy in pregnant women with mechanical prosthetic heart valves: • Avoidance of warfarin between 6 and 12 weeks of gestation due to the high risk of fetal defects. • In the absence of significant bleeding, continuous intravenous heparin should be resumed and oral warfarin should be begun four to six hours after delivery.

Class IIa - The weight of evidence or opinion is in favor of the usefulness of the the following approaches to anticoagulation therapy in pregnant women with mechanical prosthetic heart valves: • Avoidance of warfarin between 6 and 12 weeks of gestation due to the high risk of fetal defects. • In the absence of significant bleeding, continuous intravenous heparin should be resumed and oral warfarin should be begun four to six hours after delivery. • In the second and third trimesters, low-dose aspirin (75 to 100 mg/day) can be given in addition to warfarin or heparin. Dipyridamole is NOT an alternative to aspirin because of its adverse effects on the fetus. 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). Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2008; 52:e1.