Does substituting oral anticoagulants with heparin between 6 and 12 weeks of gestation improve fetal outcomes without unacceptably increasing maternal thromboembolic risk in pregnant women with mechanical heart valves?
Anticoagulation in pregnant women with mechanical valves requires a careful balance between maternal thromboembolic risk and fetal embryopathy, highlighting a critical need for large prospective trials to define the optimal regimen.
Thromboembolic prophylaxis of women with mechanical heart valves during pregnancy is best achieved with OA; however, this increases the risk of fetal embryopathy. Substituting OA with heparin between 6 and 12 weeks reduces the risk of fetopathic effects, but with an increased risk of thromboembolic complications. The use of low-dose heparin is definitely inadequate; the use of adjusted-dose heparin warrants aggressive monitoring and appropriate dose adjustment. Large prospective trials to determine the best regimen for these women are needed.
Chan et al. (Mon,) studied this question.