Managing Anticoagulation in Pregnancy
The most problematic situation is the mechanical mitral valve (particularly the tilting disc valve) and the choices of anticoagulant strategy. There are 3 strategies:
• Continuing Coumadin throughout pregnancy;
• Giving heparin (either unfractionated heparin or low-molecular-weight heparin) in the first trimester, switching back to Coumadin, and then giving heparin again predelivery; or
• Giving heparin throughout the pregnancy.
The problem is that pregnancy is the most prothrombotic state possible. It's not like managing noncardiac surgery. Heparin is not as good an anticoagulant as Coumadin, but there is a risk for embryopathy if Coumadin is taken during the first trimester. This requires a discussion with the patient. Should we accept some risk for embryopathy and have her take Coumadin during the first trimester or throughout pregnancy, or should we switch to heparin? Much has been written about that recently.
The risk for Coumadin embryopathy has been somewhat overstated. The risk is probably less than 6%. Of importance, the risk to the baby is dose-related, and that risk is very small if the mother is on less than 5 mg of Coumadin daily. Following a discussion, an individualized approach must be developed according to what the mother and her physicians want to do.
It is a common mistake to think that a woman can just be switched to low-molecular-weight heparin and all will be well. If you look at all the data that have been published in recent years on low-molecular-weight heparin and prosthetic valves, the risk for maternal thrombosis on a prosthetic valve, not even thromboembolism, is as high as 17% with low-molecular-weight heparin.[4,5]
This is why women need to be managed in special centers with all of the discussion about what is best for them, and low-molecular-weight heparin is not a straightforward and easy solution even with meticulous monitoring of anti-factor Xa.
© 2014 Mayo Clinic
Cite this: Naveen L. Pereira, Carole A. Warnes. Pregnancy in Women With Congenital Heart Disease - Medscape - Feb 03, 2014.