How is cardiomyopathy managed in pregnancy?

Management of Cardiomyopathy in Pregnancy

Most women with cardiomyopathy tolerate pregnancy well with maternal mortality being very low, and management should focus on multidisciplinary care with serial monitoring, continuation of beta-blockers (preferably metoprolol), vaginal delivery for most patients, and avoidance of myosin inhibitors like mavacamten which are contraindicated due to teratogenicity. 1

Pre-Conception Risk Stratification

Risk assessment before conception is essential using the WHO classification system to guide counseling. 1

• WHO Class II (most HCM patients): Mild to moderate left ventricular outflow tract obstruction (LVOTO), asymptomatic or well-controlled on medication, normal or mildly reduced systolic function 1
• WHO Class III: Severe LVOTO, symptomatic despite optimal medication, moderate systolic dysfunction - requires monthly or bimonthly monitoring at specialized centers 1
• WHO Class IV (pregnancy contraindicated): Severe systolic dysfunction or severe symptomatic LVOTO - pregnancy may be possible after relief of LVOTO through septal reduction therapy 1

Perform baseline echocardiography to evaluate ventricular function, mitral regurgitation, and LVOTO severity. 1 Exercise testing to 80% predicted maximal heart rate assesses functional capacity, heart rate response, and arrhythmias. 1

Genetic counseling is recommended for all women to discuss disease transmission risk (typically 50% for autosomal dominant conditions) and reproductive options including preimplantation genetic testing. 1

Medication Management During Pregnancy

Beta-Blockers (First-Line Therapy)

Continue beta-blockers if already prescribed before pregnancy, with metoprolol, bisoprolol, labetalol, pindolol, or propranolol being safe options. 1

• Avoid atenolol specifically due to evidence of potential fetal growth restriction 1
• Monitor fetal growth and fetal bradycardia when using any beta-blocker 1
• Side effects including growth retardation, neonatal bradycardia, or hypoglycemia are usually not severe and easily managed 1

Anticoagulation for Atrial Fibrillation

Use low-molecular-weight heparin or warfarin (maximum dose <5 mg daily) for stroke prevention in pregnant women with atrial fibrillation. 1

• Direct oral anticoagulants (DOACs) are contraindicated - recent meta-analysis shows higher fetal complication rates compared to low-molecular-weight heparin or warfarin 1
• Warfarin doses >5 mg daily have increased teratogenicity risk 1
• Individualize anticoagulation timing for cardioversion based on trimester and fetal risk 1

Contraindicated Medications

Mavacamten and other myosin inhibitors are absolutely contraindicated due to fetal toxicity demonstrated in animal studies. 1

Most antiarrhythmic agents are contraindicated or not recommended due to teratogenic effects. 1 Cardioversion is preferred for restoring sinus rhythm in symptomatic patients with minimal fetal risk. 1

Monitoring During Pregnancy

Frequency of Assessments

• WHO Class II patients: Assess each trimester 1
• WHO Class III patients: Monthly or bimonthly monitoring at specialized centers by multidisciplinary team 1

Serial Echocardiography

Perform echocardiography each trimester, particularly during the second or third trimester when hemodynamic load is highest, or when new symptoms develop. 1 Most complications arise in the third trimester. 1

Focus monitoring on: Symptomatic status, left ventricular outflow obstruction progression, arrhythmias, and ventricular function 1

Fetal Monitoring

Fetal echocardiography may be considered for prenatal diagnosis of hypertrophic cardiomyopathy in select families with history of pediatric disease onset or severe manifestations. 1

Delivery Planning and Management

Mode of Delivery

Vaginal delivery is the preferred mode for most women with cardiomyopathy, as adverse outcomes during delivery are low (3-4%) and similar between vaginal and cesarean delivery. 1

• Reserve cesarean section only for obstetric indications or emergency cardiac/maternal health reasons 1
• Cesarean section has higher bleeding rates including serious bleeding requiring transfusions 1
• Valsalva maneuver during labor is well tolerated 1
• Establish delivery plan by end of second trimester 1

Anesthesia

Both epidural and general anesthesia are reasonable options with precautions to avoid hypotension. 1

• No contraindications to either form in HCM patients as long as hypotension is avoided 1
• Monitor heart rate and rhythm during delivery in patients at high risk for arrhythmias 1
• Administer oxytocin only as slow infusion to avoid hypotension and tachycardia 1

Post-Delivery Monitoring

Continue clinical observation for 24-48 hours post-delivery due to increased risk of pulmonary edema from fluid shifts. 1

Multidisciplinary Team Approach

A multidisciplinary care team including cardiologists and maternal-fetal medicine specialists provides comprehensive management. 1 The team should include nurses, obstetricians, neonatologists, anesthesiologists, and cardiac surgeons when appropriate. 2

Shared decision-making should convey that maternal mortality is very low, with cardiac events occurring primarily in those with preexisting symptoms and previous cardiac events. 1

Key Clinical Pitfalls to Avoid

• Do not use atenolol - choose alternative beta-blockers 1
• Do not prescribe DOACs for anticoagulation during pregnancy 1
• Do not routinely perform cesarean section - reserve for specific indications only 1
• Do not give oxytocin as rapid bolus - use slow infusion only 1
• Do not withhold necessary maternal medications due to fetal concerns when mother's health is threatened - maternal interests should prevail 1
• Do not deactivate ICDs during vaginal delivery 1