Peripartum Cardiomyopathy (PPCM)

DEFINITION, Etiology, PATHOGENESISTop

Peripartum cardiomyopathy (PPCM) is an idiopathic pregnancy-associated dilated cardiomyopathy (DCM) characterized by the development of marked left ventricular (LV) dysfunction towards the end of pregnancy or in the postpartum period. Incidence rates vary significantly depending on geographic location. PPCM has been estimated to affect up to 1 in 2400 births in Canada.

The pathogenesis of PPCM remains unclear. Current thinking proposes a “two-hit” model. Patients with an underlying genetic predisposition are exposed to a vascular insult, which induces the development of PPCM. The proposed etiologies of the second vascular “hit” include viral myocarditis, hemodynamic stress of pregnancy, increased myocyte apoptosis, excessive prolactin production and/or other hormonal changes of pregnancy, preeclampsia, or nutritional deficiencies.

Risk Factors

Identified risk factors for PPCM include advanced maternal age, previous history of PPCM, preeclampsia, eclampsia, hypertension, multiple gestation, and Black ancestry.

CLINICAL FEATURESTop

Presenting symptoms are those of heart failure. These include shortness of breath on exertion, orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, palpitations, cough, or chest tightness.

Physical examination findings can be subtle or overt. Patients may have an S3 gallop, which can also be a normal finding of pregnancy; elevated jugular venous pressure (JVP); elevated respiratory rate; tachycardia; peripheral edema; or pulmonary rales or crackles.

It is important to recognize that early signs and symptoms of heart failure in young women can mimic normal physiologic changes during or after pregnancy (physiologic vs pathologic manifestations in pregnancy: Table 1). Persistent tachycardia >115 beats/min is above the upper limit of normal (ULN) at any gestational age and, particularly in the setting of shortness of breath, cough, or orthopnea, requires a positive diagnosis.

Differential diagnosis of shortness of breath in pregnancy: Table 2.

Timing of Presentation

Traditionally the timing of presentation is during the last few weeks of pregnancy prior to delivery or in the first weeks to months post partum. Women who have an earlier presentation should have a full evaluation for alternative causes, as the diagnosis of PPCM is far less likely (see Dilated Cardiomyopathy).

DiagnosisTop

Diagnostic Criteria

PPCM is diagnosed after careful history taking and with physical examination demonstrating symptom onset towards the end of pregnancy or in the weeks to months following pregnancy with objective echocardiographic evidence of LV dysfunction and an ejection fraction (EF) <45% towards the end of pregnancy or in the months following delivery if all other causes of DCMs (see Dilated Cardiomyopathy) have been excluded.

Diagnostic Tests

See Dilated Cardiomyopathy.

All patients with suspected PPCM should have blood drawn for further evaluation, including:

1) Complete blood count (CBC) and peripheral smear; creatinine; alanine aminotransferase (ALT); midstream urinalysis, urine protein-to-creatinine ratio, or 24-hour urine protein test: These are performed to exclude preeclampsia and HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, which can overlap with PPCM, and to exclude other potential diagnoses.

2) Electrolytes: Baseline sodium and potassium levels should be documented prior to initiating diuretic therapy.

3) Troponin: Troponin levels can be mildly elevated in PPCM but they are not diagnostic.

4) B-type natriuretic peptide (BNP): BNP values should not be elevated in pregnancy.

Further diagnostic testing should be guided by differential diagnoses and may include the following:

1) Transthoracic echocardiography (TTE), which is required for the diagnosis of PPCM. Images reveal reduced left ventricular ejection fraction (LVEF) and DCM with or without valvular disease.

2) Electrocardiography (ECG) may show normal sinus rhythm.

3) Chest radiography may show pulmonary edema, pleural effusion, or cardiomegaly.

4) Pulmonary ultrasonography may show pulmonary edema and pleural effusions.

5) Computed tomography pulmonary angiography (CTPA) is performed to exclude pulmonary embolism only if an alternative differential diagnosis is being considered.

6) Cardiac magnetic resonance imaging (MRI) is typically reserved for diagnostic workup when TTE studies are technically limited.

7) Pulmonary function testing (PFT) may be used to exclude asthma.

TreatmentTop

General Approach

The management of PPCM should be divided into the antepartum, intrapartum, and postpartum periods (depending on the timing of diagnosis). The mainstay of treatment is focused on optimizing hemodynamic status and preventing potential complications. A multidisciplinary approach is of paramount importance. Members of the multidisciplinary team (MDT) may include experts in high-risk obstetrics, obstetric medicine, cardiology, neonatology, anesthesiology, and allied health and intensive care, as indicated. The level and location of care should be discussed on a case-by-case basis and may be dependent on the timing and severity of symptoms, local expertise, and potential for maternal or fetal decompensation.

Nonpharmacologic management of PPCM may include fluid restriction, salt restriction, and daily weight monitoring.

Pharmacologic management: Table 3.

Advanced Management

Management in severe LV dysfunction and acute decompensated heart failure nonresponsive to medical management: see Dilated Cardiomyopathy.

Intrapartum Management

In cases where patients are hemodynamically stable, early delivery has not been shown to improve maternal or fetal outcomes in PPCM. Decisions on the mode and timing of delivery should therefore be guided by obstetric indications unless there are signs of acute heart failure and cardiogenic shock. Antenatal patients should be managed in hospital and daily MDT assessment is vital to detect maternal or fetal decompensation. Stabilization of the mother prior to delivery is a priority. Early delivery (and possibly caesarean section) should be considered in cases of refractory hemodynamic or cardiorespiratory instability (maternal or fetal) with input from all members of the MDT. Antepartum and postpartum fluid intake and output should be monitored strictly to avoid fluid overload, and monitoring for complications should occur in a high-dependency unit or in intensive care setting for ≥48 hours post partum.

Poor prognostic indicators include LVEF <30% and left ventricular end-diastolic diameter (LVEDD) >6 cm. Women with these parameters are at decreased risk of LV recovery and at increased risk of mechanical support, transplant, and death. Complications may also arise in the peripartum period and are often related to the degree of cardiac dysfunction. Increased risks of arrhythmias, thromboembolic events, decompensated heart failure, and cardiogenic shock contribute to significant maternal and fetal morbidity and mortality.

Postpartum Management and Follow-Up

All women with a diagnosis of PPCM should have a close clinical and echocardiographic follow-up by a cardiologist in the postpartum period. Reassuringly, a large proportion of women demonstrate full recovery of their LV function in the first 6 months. If LV function then remains normal for further 6 months, stepwise tapering of heart failure medications can be considered.

If LV function remains poor for >6 months, chances of LV recovery decrease significantly. An EF <30% at the time of diagnosis is also associated with lower rates of recovery.

Subsequent Pregnancies

In women without LV recovery, there is an increased risk of worsening cardiac function and mortality in future pregnancy. In these instances, further pregnancies are contraindicated and a strong form of contraception must be advised.

In women with LV recovery who are planning a subsequent pregnancy, assessment and referral to an MDT including a high-risk obstetrician, cardiologist familiar with PPCM, specialist in obstetric medicine, or all of these is recommended for preconception assessment. Contraception should not be discontinued until there is echocardiographic evidence of a normal EF without cardiac medications for ≥6 months and any additional workup for predisposing conditions is complete.

Once pregnancy is confirmed, a baseline echocardiogram and BNP measurement should be performed. Women should be followed by high-risk obstetric and cardiology teams with serial monitoring for the development of cardiac dysfunction. We routinely obtain echocardiograms at the end of the first and second trimester, one month before delivery, and with any symptom development. BNP levels can also be used as an adjunctive surveillance tool and should also be checked if symptoms arise.

ComplicationsTop

Thromboembolism

There are higher rates of thromboembolism (6.6%) related to PPCM compared with other cardiomyopathies due to the hypercoagulable state in the peripartum period. There is some discrepancy between different national guidelines regarding thromboprophylaxis. The European Society of Cardiology (ESC) recommends prophylactic anticoagulation in patients with PPCM and LVEF <35% and additionally in those who are receiving bromocriptine. Guidelines of the American Heart Association (AHA) recommend prophylactic anticoagulation in women with PPCM and LVEF <30%. Therapeutic anticoagulation is reserved for patients who have an intracardiac thrombus or evidence of venous thromboembolism, as in standard guidelines for nonpregnant patients.

Arrhythmias

The prevalence of arrhythmias associated with PPCM is quite variable, but hospitalized patients with PPCM seem to be at the highest risk (18.7% of all hospitalized patients). Cardioversion and defibrillation are considered safe in pregnancy and should be performed without delay for usual indications. Given the high rate of recovery in PPCM, placement of an implantable cardioverter-defibrillator (ICD) for primary or secondary prevention within the first 6 months post partum should be carefully considered on a case-by-case basis.

TablesTop