Peripartum Cardiomyopathy

A 35-year-old woman presents with fatigue, shortness of breath, and lower extremity swelling four weeks after delivering her third child. An echocardiogram reveals a dilated left ventricle with an ejection fraction of 30%. Her medical history is only significant for pre-eclampsia during her first pregnancy.

Pathophysiology

The underlying mechanisms behind peripartum cardiomyopathy (PPCM) remain elusive, and several theories have been proposed. One hypothesis suggests that PPCM might be a form of myocarditis triggered by an abnormal immune response to fetal cells in the maternal circulation. Around the time of delivery, a "loss of tolerance" to these cells may lead to an inflammatory reaction in the myocardium.

Another theory suggests a role for abnormal cleavage of the nursing hormone prolactin into a 16-kDa antiangiogenic and proapoptotic protein. This cleavage product is thought to be cardiotoxic and may contribute to the development of PPCM.

Aetiology

The precise cause of PPCM is unknown; however, it is considered an idiopathic cardiomyopathy. Some potential contributing factors and associations have been identified:

• Genetic predisposition: PPCM may have a genetic component, as it sometimes runs in families.
• Immunological factors: The abnormal immune response to fetal cells, as mentioned above, could be involved.
• Hormonal changes: The dramatic hormonal shifts during pregnancy and the postpartum period may play a role.
• Nutritional deficiencies: Low levels of selenium have been associated with an increased risk of PPCM in some studies.
• Pre-eclampsia/eclampsia: A history of pre-eclampsia or eclampsia is a recognised risk factor for PPCM.

Epidemiology & Risk Factors

PPCM is a rare condition, estimated to affect less than 1 in 2000 births in European countries. Certain factors can increase the risk of developing PPCM:

• Advanced maternal age: Older mothers have a higher risk.
• Multiparity: Women who have given birth multiple times are more likely to develop PPCM.
• Multiple gestations: Carrying twins or triplets increases the risk.
• African-Caribbean race: Women of African-Caribbean descent have a higher incidence of PPCM.
• Hypertension: Both chronic hypertension and pregnancy-induced hypertension are associated with an increased risk.
• Pre-eclampsia/eclampsia: As mentioned above, these conditions are significant risk factors.

Clinical Features

PPCM typically presents with symptoms of heart failure:

• Fatigue
• Dyspnoea and Orthopnoea
• Peripheral oedema
• Ascites
• Tachycardia
• Cough
• Reduced ability to exercise

Mostly commonly in the first month after delivery but can occur during pregnancy, commonly in 3rd trimester.

Less commonly presents with:

• Thromboembolic event
• Cardiogenic shock

Investigations

Diagnosing PPCM involves ruling out other potential causes of heart failure and confirming the presence of left ventricular systolic dysfunction. The following investigations are helpful:

• Echocardiogram: This is the key diagnostic test, revealing a dilated left ventricle with reduced ejection fraction (EF). The EF is often below 45%, and the fractional shortening is less than 30%.
• Chest X-ray: May show cardiomegaly and signs of pulmonary congestion.
• Electrocardiogram: May show non-specific abnormalities such as tachycardia or T-wave inversions.
• Blood tests: Primarily used to exclude other causes of heart failure and assess kidney function. Elevated BNP may support the diagnosis of heart failure.

Management

The management of PPCM is similar to that of heart failure in other settings, with the primary goal of improving cardiac function and relieving symptoms. Multidisciplinary involvement should be sought, including cardiology, obstetrics, anaesthetics and neonatology. Treatment approaches include:

Lifestyle Modifications

• Fluid restriction: Limiting fluid intake can help manage fluid overload and reduce symptoms of congestion.
• Salt restriction: Lowering dietary sodium intake can help control fluid retention and blood pressure.
• Bed rest: Rest is recommended during the acute phase of PPCM to reduce cardiac workload.

Obstetric Modifications

• Determine optimal timing in consultation with obstetrics and cardiology
  • If stable, vaginal delivery at term may be feasible
  • If unstable, urgent caesarean section
• Breastfeeding should be delayed if acutely decompensated, but encouraged if stable. Consider need to modify medications in this instance.
• Preconception counselling regarding future pregnancies.

Medical Management

• Diuretics: Diuretics, such as furosemide, help eliminate excess fluid and reduce pulmonary congestion.
• Vasodilators: Medications like nitrates (e.g., GTN) can help lower blood pressure and reduce afterload, improving cardiac output.
• Beta-blockers: Beta-blockers, like carvedilol, can help slow the heart rate, reduce blood pressure, and improve heart function. However, they should be used cautiously in patients with severe heart failure, as they can worsen symptoms initially.
• ACE inhibitors: ACE inhibitors (e.g. ramipril) are generally avoided during pregnancy due to potential risks to the fetus but are often initiated after delivery to improve long-term outcomes.
• Digoxin: Digoxin may be used to improve heart contractility and control heart rate in some patients.
• Anticoagulation: Anticoagulation with heparin is often recommended to prevent blood clots, especially in the postpartum period when the risk of thrombosis is increased, in cases with reduced EF or previous thromboembolism.
  • Can consider warfarin whilst breast feeding but not whilst pregnant.

Surgical Management

• Heart transplantation: Heart transplantation may be considered in cases of severe, refractory heart failure that does not respond to medical therapy.

Complications & Prognosis

PPCM can lead to serious complications, including:

• Worsening heart failure
• Arrhythmias, such as atrial fibrillation or ventricular tachycardia
• Stroke
• Sudden cardiac death

The prognosis for PPCM is variable. About half of the women with PPCM experience complete or near-complete recovery of heart function within the first six months postpartum. However, some women continue to have persistent heart failure, requiring ongoing medical therapy. A small percentage of women may experience progressive deterioration, leading to death or the need for a heart transplant.

The risk of PPCM recurrence and mortality significantly increases with subsequent pregnancies.

• If LV function has recovered, shared discussion with cardiology and obstetrics regarding future pregnancy.
• If LV function remains poor, future pregnancy bears significant risk of deterioration.
  • Contraception counselling should be provided: oestrogen-containing contraceptives are best avoided immediately postpartum due to increased thromboembolic risk.