- Cardiovascular disease contributes to approximately 1/3 of all maternal mortality
- Cardiologists with expertise in cardioobstetrics and high-risk obstetricians should co-manage pregnant women with prosthetic heart valves, mitral stenosis, aortic stenosis, dilated cardiomyopathy or peripartum cardiomyopathy, among other high-risk conditions
- In general, planned vaginal delivery is recommended over cesarean section for women with high-risk cardiac conditions
Maternal mortality in the U.S. has been climbing since 1984 with an estimated mortality rate of 17 per 100,000 live births in 2013. It is thought that higher rates of cardiovascular disease (CVD) observed among pregnant women is an important contributor. More women are delaying childbearing, and more women with congenital heart disease and cardiomyopathy (CMP) related to childhood cancer treatment are surviving into adulthood. CVD contributes to about one-third of maternal mortality and is the source of substantial peri- and postpartum morbidity.
In Trends in Cardiovascular Medicine, Doreen DeFaria Yeh, MD, associate director of the Mass General Adult Congenital Heart Disease Program and co-director of the Mass General Cardiovascular Disease and Pregnancy Service, and research fellow Emily Lau, MD, urge general cardiologists and obstetricians to collaborate in the peri- and postpartum management of women with CVD. They review recommendations for some of the major high-risk cardiac conditions.
Pregnancy is a period of marked hypercoagulability, and thrombotic risk does not resolve until 12 weeks postpartum. Drs. Lau and DeFaria Yeh limit their discussion to the management of women with prosthetic heart valves, but note that pregnant women with thrombophilias or a history of venous thromboembolism are also at risk.
For women with prosthetic heart valves, the 2014 American Heart Association guidelines recommends warfarin ≤5 mg/day throughout pregnancy, even during the first trimester. However, there is a residual risk of adverse fetal events. As such, many expert centers use low-molecular-weight heparin (LMWH), which does not cross the placenta. There is a significant increase in glomerular filtration rate during pregnancy, so both peak and trough anti-Xa levels should be checked routinely to ensure correct dosing.
At the time of delivery, women on LMWH should be transitioned to unfractionated heparin (UFH) to maximize the opportunity for neuraxial anesthesia. The American College of Obstetricians and Gynecologists recommends waiting 24 hours prior to neuraxial blockade for women taking therapeutic LMWH, 12 hours for UFH >10,000 IU/day, and four to six hours for prophylactic doses of UFH Mitral Stenosis
Women with mitral stenosis who are considering pregnancy should be referred to a tertiary clinic with expertise in cardio-obstetrics. Women with moderate or severe mitral stenosis have a significantly elevated risk of adverse maternal and fetal outcomes and are advised to avoid pregnancy until they have undergone an extensive evaluation with a multidisciplinary team of cardiologists and high-risk obstetricians.
Women with severe mitral stenosis will require valve intervention prior to pregnancy to avoid serious cardiac and obstetrical adverse outcomes. Beta blockade and diuretics are the mainstay of therapy intrapartum.
Aortic stenosis in pregnancy is generally better tolerated than mitral stenosis, but regardless, it is associated with high rates of adverse maternal complications including heart failure (HF), tachyarrhythmias and pulmonary edema. Management involves beta blockade, diuresis and restriction of activity to maintain normal intracardiac filling pressures. Women with severe aortic stenosis and symptoms should undergo valve intervention prior to pregnancy. Women with intractable HF during pregnancy should be evaluated for intrapartum valve intervention.
Left ventricular ejection fraction (LVEF) <40% or New York Heart Association functional class III or IV are risk factors for adverse maternal outcomes such as HF, arrhythmias and transient ischemic attack. Some other possible outcomes are preeclampsia, postpartum hemorrhage, low birth weight or preterm delivery.
Medical management of dilated CMP in pregnancy is similar to that of non-pregnant patients, except that angiotensin-converting enzyme inhibitors and aldosterone antagonists are teratogenic and should be replaced with hydralazine or amlodipine. In the case of acute decompensation, IV diuretics and/or nitroglycerin can be administered.
Labor and delivery is a vulnerable time for women with dilated CMP, so a team of cardiologists, obstetricians and obstetrical anesthesiologists should be available for immediate consultation. As in other high-risk pregnancies, an increasing number of studies show that outcomes are better with planned vaginal delivery than with cesarean section.
Another vulnerable time for these patients is the immediate postpartum period when systemic vascular resistance and volume can increase dramatically due to delivery and autotransfusion of the placenta. Women may decompensate quickly, so it is important to continue hemodynamic and electrocardiographic monitoring for at least several days after delivery.
Peripartum CMP is defined as HF in late pregnancy or within several months following delivery, in the absence of another etiology. Known risk factors are older maternal age, teenage pregnancy, multiparity, multifetal pregnancy, African or Haitian descent, hypertension, diabetes, prior toxin exposure, preeclampsia and smoking. Medical management is similar to dilated CMP in pregnancy.
LVEF in these women generally improves after delivery, but it often drops again in subsequent pregnancies. As such, patients should be counseled about that risk before considering a subsequent pregnancy. A contraception plan should be discussed prior to hospital discharge.
The authors close by emphasizing that physician awareness of potential complications in pregnant women with CVD is vitally important to their health and the health of their infants. Expanding education on pregnancy and CVD to cardiologists and cardiology trainees is critical to improve outcomes.
Learn more about Mass General's approach to Pregnancy and Heart Disease
Refer a patient to the Mass General Heart Center