What is postpartum cardiomyopathy?

Definition of Postpartum Cardiomyopathy

Postpartum cardiomyopathy (PPCM) is an idiopathic cardiomyopathy presenting with heart failure secondary to left ventricular systolic dysfunction towards the end of pregnancy or in the months following delivery, where no other cause of heart failure is found. 1

Core Diagnostic Criteria

• PPCM is a diagnosis of exclusion that occurs without any other determinable heart disease 1, 2
• The left ventricle may not be dilated, but the ejection fraction is nearly always reduced below 45% 1
• Traditionally defined as occurring during the last month of pregnancy or within 5 months postpartum, though this timeframe is considered arbitrary and may lead to under-diagnosis 1
• Distinct from other types of heart failure, with a unique clinical course that can include rapid progression to end-stage heart failure or spontaneous recovery 1

Epidemiology

• Incidence varies worldwide: approximately 1 in 2500-4000 in the USA, 1 in 1000 in South Africa, and 1 in 300 in Haiti 1
• Higher prevalence in women with black ancestry, particularly in Nigeria and Haiti 3
• Represents a rare but potentially life-threatening condition in previously healthy young women 4

Clinical Presentation

• Most patients (78%) develop symptoms in the first 4 months after delivery, with only 9% presenting in the last month of pregnancy 1
• Common symptoms include dyspnea, fatigue, and peripheral edema, which may be mistaken for normal pregnancy symptoms 1
• Physical examination may reveal a displaced apical impulse (72%), third heart sound (92%), and mitral regurgitation (43%) 1
• Presentation severity ranges from NYHA class I to IV symptoms, with most patients presenting with class III or IV 1

Pathophysiology

Several mechanisms have been proposed:

• Oxidative stress activating cathepsin D in cardiomyocytes, which cleaves prolactin into a cardiotoxic 16 kDa fragment 1
• This prolactin fragment inhibits endothelial cell proliferation, induces endothelial cell apoptosis, disrupts capillary structures, and impairs cardiomyocyte function 1
• Autoimmune responses may play a role, with high titers of auto-antibodies against cardiac tissue proteins found in many PPCM patients 1
• Potential genetic susceptibility, with some cases possibly representing an initial manifestation of familial dilated cardiomyopathy 1

Diagnostic Workup

• Echocardiography is essential, showing reduced left ventricular ejection fraction (<45%) 1
• Electrocardiogram often shows abnormalities (ST-T wave changes in 96%, LV hypertrophy voltage criteria in 66%) 1
• B-type natriuretic peptide (BNP) or NT-proBNP levels are typically elevated 1
• Cardiac MRI provides more accurate assessment of chamber volumes and ventricular function, and can detect LV thrombus 1
• Differential diagnosis must exclude pre-existing cardiac conditions, hypertensive heart disease, pulmonary embolism, and other causes of heart failure 1

Complications

• Left ventricular thrombosis is common in patients with LVEF <35%, leading to risk of systemic emboli 1
• Potential for cardiogenic shock, arrhythmias, and thromboembolic events 5
• Mortality rates vary widely (0-25%) depending on geographic location 6

Prognosis

• More than half of affected women recover systolic function 3
• Some patients develop chronic cardiomyopathy requiring long-term management 3
• A minority requires mechanical circulatory support or cardiac transplantation 3
• Poor prognostic indicators include delayed diagnosis and thromboembolic complications 5
• Risk of relapse in subsequent pregnancies is high 2