What are the cardiac contraindications to pregnancy in women with pre-existing cardiac conditions, such as pulmonary hypertension, left ventricular dysfunction, or complex congenital heart disease?

Cardiac Contraindications to Pregnancy

Pregnancy is absolutely contraindicated (WHO Class IV) in women with pulmonary arterial hypertension of any cause, severe systemic ventricular dysfunction (LVEF <30% or NYHA III-IV), Marfan syndrome with aortic dilatation >45mm, severe symptomatic aortic stenosis, aortic dilatation >50mm with bicuspid aortic valve, native severe coarctation, and previous peripartum cardiomyopathy with any residual left ventricular impairment. 1

Absolute Contraindications (WHO Class IV)

Pulmonary Arterial Hypertension

• Any degree of pulmonary hypertension (mean PAP ≥25 mmHg by older definition or >20 mmHg by newer definition) is an absolute contraindication to pregnancy. 1, 2
• Maternal mortality remains 17-33% in recent studies, with older series reporting 30-50%. 1, 2
• Deaths occur predominantly in the last trimester and first months postpartum due to pulmonary hypertensive crises, pulmonary thrombosis, or refractory right heart failure. 1, 2
• Even moderate pulmonary hypertension can worsen during pregnancy due to decreased systemic vascular resistance and right ventricular volume overload—there is no safe cut-off value. 1, 2
• This includes Eisenmenger syndrome, where maternal mortality is 20-50% and live birth is unlikely (<12%) if oxygen saturation is <85%. 1
• If pregnancy occurs despite counseling, termination should be offered and performed in a tertiary center experienced in PAH management. 1

Severe Left Ventricular Dysfunction

• LVEF <30% or NYHA functional class III-IV heart failure is an absolute contraindication. 1
• The fixed cardiac output cannot accommodate the 40-50% increase in blood volume during pregnancy. 1

Severe Left Ventricular Outflow Tract Obstruction

• Severe symptomatic aortic stenosis is contraindicated and should be treated before pregnancy. 1
• A fixed outflow tract resistance cannot accommodate increased cardiac output, leading to heart failure, low output state, and pulmonary congestion. 1
• Women should be counseled against pregnancy until relief of stenosis is obtained. 1

Aortic Dilatation

• Marfan syndrome with aortic diameter >45mm is an absolute contraindication. 1
• Bicuspid aortic valve with aortic dilatation >50mm is contraindicated. 1
• Risk of spontaneous aortic dissection or rupture, particularly in the third trimester. 1
• Any woman with Marfan syndrome should be counseled against pregnancy due to risk of aortic rupture or dissection even with normal dimensions. 1

Previous Peripartum Cardiomyopathy

• Any residual impairment of left ventricular function after previous peripartum cardiomyopathy is an absolute contraindication. 1

Native Severe Coarctation

• Unoperated severe coarctation of the aorta is contraindicated. 1
• Rupture of the aorta is the most common reported cause of death during pregnancy. 1

High-Risk Conditions (WHO Class III)

Cyanotic Congenital Heart Disease

• If resting oxygen saturation is <85%, pregnancy is contraindicated due to substantial maternal and fetal mortality risk. 1
• If oxygen saturation is 85-90%, exercise testing should be performed; significant early desaturation indicates poor prognosis. 1
• Maternal complications (heart failure, thrombosis, arrhythmias, endocarditis) occur in 30% of cases. 1
• Overall maternal mortality is approximately 2% with high complication rates. 1

Mechanical Heart Valves

• Mechanical valves represent WHO Class III risk due to anticoagulation requirements and associated maternal/fetal complications. 1

Systemic Right Ventricle and Fontan Circulation

• These complex anatomies carry WHO Class III risk with significantly increased maternal mortality or severe morbidity. 1

Moderate Aortic Dilatation

• Marfan syndrome with aortic diameter 40-45mm is WHO Class III. 1
• Bicuspid aortic valve with aortic diameter 45-50mm is WHO Class III. 1

Critical Management Principles

Pre-Pregnancy Counseling

• All women with significant heart disease must receive expert pre-pregnancy counseling outlining specific maternal and fetal risks. 1, 3
• Disease-specific risk assessment should be performed before conception, including echocardiography and exercise testing. 1, 3

If Contraindicated Pregnancy Occurs

• Termination should be discussed and offered, performed in a tertiary center with expertise in the specific cardiac condition. 1
• If the patient chooses to continue despite contraindication, management requires a multidisciplinary expert team in a specialized center with all therapeutic options available. 1, 3

Common Pitfall

• Do not assume that asymptomatic status before pregnancy predicts safe pregnancy outcome in contraindicated conditions—deaths occur even in patients with little or no disability before pregnancy. 1