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Mechanical Aortic Valve Replacement in Young Women Planning on Pregnancy: Maternal and Fetal Outcomes Under Low Oral Anticoagulation, a Pilot Observational Study on a Comprehensive Pre-Operative Counseling Protocol
Study Questions:
What are the maternal and fetal outcomes of pregnancies managed with low-dose oral anticoagulation therapy after mechanical aortic valve replacement?
Methods:
A comprehensive preoperative counseling protocol was developed and tested to guide the choice of aortic valve replacement. The main purpose of the protocol was a preoperative anticoagulation trial to determine the warfarin daily dosage needed to reach target international normalized ratio (INR). Pregnancies on low-dose anticoagulation therapy (target international normalized ratio [INR] 1.5-2.5) were allowed in a highly selected subset of women after mechanical aortic valve replacement.
Results:
Of 40 patients originally referred for native valve disease, 18 were referred for valve repair procedures; the remaining 22 safely underwent a preoperative anticoagulation challenge and went on to valve replacement. The daily warfarin dose required was >5 mg in five patients; three of these underwent bioprosthetic valve replacement and two underwent mechanical valve replacement. The daily warfarin dose was <5 mg in 17 patients, all of whom underwent mechanical valve replacement with a St. Jude Medical bileaflet prosthesis. Of these 17, one pregnancy was carried out using low molecular weight heparin (LMWH); this patient experienced valve thrombosis in the 11th week of pregnancy despite medication compliance and dose adjustment to maintain peak anti-Xa levels therapeutic. Of 16 pregnancies managed with “the Cotrufo protocol” (low-dose warfarin therapy [INR 1.5-2.5] throughout pregnancy), all had full-term babies with no complications.
Conclusions:
In this small sample observational study, a preoperative anticoagulation therapy trial helped young women scheduled for valve replacement in their choice of prosthesis. In selected patients who underwent aortic valve replacement with a third-generation mechanical prosthesis, low-dose anticoagulation therapy throughout pregnancy (INR 1.5-2.5) was safe for both mother and fetus.
Perspective:
Valve replacement is problematic among any young patient, and even more so among women of childbearing age. Although bioprosthetic valve replacement obviates the need for anticoagulation during pregnancy, repeat valve surgery is likely in this young population. (Earlier concerns that pregnancy causes accelerated bioprosthesis structural deterioration probably are unfounded.) Valve replacement with a mechanical prosthesis requires long-term anticoagulation throughout pregnancy, with special concern about teratogenic effects of warfarin during the first trimester. This small study suggests that, among women who require elective aortic valve replacement and plan a future pregnancy, a preoperative trial to determine warfarin dose can help guide valve selection, using a mechanical valve among women with a daily warfarin dose <5 mg to maintain an INR 1.5-2.5, and simply continuing low-dose warfarin throughout pregnancy.
Keywords: Heart Valve Prosthesis, Heparin, Low-Molecular-Weight, Warfarin, Counseling, International Normalized Ratio, Medication Adherence, Bioprosthesis, Thrombosis, Fetus, Mothers, Pregnancy Trimester, First, Pregnancy
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