Maternal and Fetal Outcomes in Pregnant Women with a Prosthetic Mechanical Heart Valve
Authors: Ayad Sherif W. , Hassanein Mahmoud M. , Mohamed Elsayed A. , Gohar Ahmed M. 
Published: February 2016

Background

Pregnancy is associated with several cardiocirculatory changes that can significantly impact underlying cardiac disease. These changes include an increase in cardiac output, sodium, and water retention leading to blood volume expansion, and reductions in systemic vascular resistance and systemic blood pressure. In addition, pregnancy results in a hypercoagulable state that increases the risk of thromboembolic complications.

Objectives

The aim of this study is to assess the maternal and fetal outcomes of pregnant women with mechanical prosthetic heart valves (PHVs).

Methods

This is a prospective observational study that included 100 pregnant patients with cardiac mechanical valve prostheses on anticoagulant therapy. The main maternal outcomes included thromboembolic or hemorrhagic complications, prosthetic valve thrombosis, and acute decompensated heart failure. Fetal outcomes included miscarriage, fetal death, live birth, small-for-gestational age, and warfarin embryopathy. The relationship between the following were observed: – Maternal and fetal complications and the site of the replaced valve (mitral, aortic, or double) – Maternal and fetal complications and warfarin dosage (≤5 mg, >5 mg) – Maternal and fetal complications and the type of anticoagulation administered during the first trimester

Results

This study included 60 patients (60%) with mitral valve replacement (MVR), 22 patients (22%) with aortic valve replacement (AVR), and 18 patients (18%) with double valve replacement (DVR). A total of 65 patients (65%) received >5 mg of oral anticoagulant (warfarin), 33 patients (33%) received ≤5 mg of warfarin, and 2 patients (2%) received low-molecular-weight heparin (LMWH; enoxaparin sodium) throughout the pregnancy. A total of 17 patients (17%) received oral anticoagulant (warfarin) during the first trimester: 9 patients received a daily warfarin dose of >5 mg while the remaining 8 patients received a daily dose of ≤5 mg. Twenty-eight patients (28%) received subcutaneous (SC) heparin calcium and 53 patients (53%) received SC LMWH (enoxaparin sodium). Prosthetic valve thrombosis occurred more frequently in patients with MVR ( P = 0.008). Postpartum hemorrhage was more common in patients with aortic valve prostheses than in patients with mitral valve prostheses ( P 0.005). The incidence of perinatal death was higher in patients with AVR ( P 0.014). The incidence of live birth was higher in patients with DVR ( P 0.012). The incidence of postpartum hemorrhage was higher in patients who received a daily dose of >5 mg of warfarin than in patients who received ≤5 mg of warfarin ( P 0.05). The incidence of spontaneous abortion was also higher in patients receiving >5 mg of warfarin (P ≤ 0.001), while the incidence of live births was higher in patients receiving ≤5 mg of warfarin ( P 0.008). There was a statistically significant difference between the anticoagulant received during the first trimester and cardiac outcomes. Specifically, patients on heparin developed more heart failure ( P 0.008), arrhythmias ( P 0.008), and endocarditis ( P 0.016). There was a statistically significant relationship between heparin shifts during the first trimester and spontaneous abortion ( P 0.003).

Conclusion

Warfarin use during the first trimester is safer for the mother but is associated with more fetal loss, especially in doses that exceed 5 mg. The incidence of maternal complications is greater in women who receive LMWH or unfractionated heparin during the first trimester, especially prosthetic valve thrombosis, although the fetal outcome is better because heparin does not cross the placenta.