Restrictive Cardiomyopathy (RCM)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Patient Advice

Definition

Restrictive Cardiomyopathy (RCM) is a condition characterised by impaired ventricular filling due to reduced myocardial compliance, while systolic function typically remains normal. It leads to diastolic heart failure and elevated atrial pressures.

Aetiology

RCM can result from various causes, which are divided into primary (idiopathic) and secondary forms:

• Idiopathic: No identifiable cause.
• Infiltrative Diseases: E.g., amyloidosis (most common), sarcoidosis.
• Storage Disorders: E.g., haemochromatosis, Fabry disease.
• Fibrotic Conditions: Post-radiation therapy or endomyocardial fibrosis.
• Systemic Diseases: E.g., scleroderma or lupus.

Pathophysiology

RCM results in diastolic dysfunction and increased atrial pressures:

• Reduced Myocardial Compliance: Stiffened ventricular walls limit filling during diastole.
• Elevated Atrial Pressures: Resistance to ventricular filling causes atrial dilation.
• Pulmonary Congestion: Back pressure leads to pulmonary venous congestion and symptoms of heart failure.

Risk Factors

Key risk factors for RCM include:

• Family history of cardiomyopathy.
• Systemic inflammatory or infiltrative diseases.
• Exposure to radiation therapy.
• Chronic iron overload (haemochromatosis).

Signs and Symptoms

RCM may present with non-specific symptoms of heart failure:

• Dyspnoea: Shortness of breath on exertion or at rest.
• Fatigue: Persistent tiredness and reduced exercise tolerance.
• Peripheral Oedema: Swelling in the legs and ankles.
• Ascites: Abdominal swelling due to fluid accumulation.
• Palpitations: Awareness of irregular or rapid heartbeats.
• Syncope: Fainting episodes, particularly with exertion.

Investigations

Key investigations and findings include:

• Electrocardiogram (ECG):
  • Non-specific changes, such as low voltage QRS complexes.
  • P-wave abnormalities indicating atrial enlargement.
• Echocardiography: Demonstrates normal ventricular thickness and systolic function but impaired diastolic filling.
• Cardiac MRI: May reveal myocardial fibrosis or infiltration (e.g., late gadolinium enhancement).
• Blood Tests:
  • Brain Natriuretic Peptide (BNP): Elevated due to heart failure.
  • Iron Studies: To rule out haemochromatosis.
  • Serum Protein Electrophoresis (SPEP): To detect monoclonal proteins in amyloidosis.

Management

1. Acute Management

• Diuretics: To relieve symptoms of fluid overload.
• Oxygen Therapy: For hypoxia due to pulmonary congestion.
• Anti-arrhythmics: For atrial fibrillation or other arrhythmias.

2. Chronic Management

• Diuretics: E.g., furosemide to manage fluid retention.
• Beta-blockers: To control heart rate and improve diastolic filling time.
• ACE Inhibitors: To reduce afterload and improve symptoms.
• Anticoagulation: For atrial fibrillation or risk of thromboembolism.
• Treatment of Underlying Causes: E.g., iron chelation for haemochromatosis, or specific therapy for amyloidosis.

3. Specialist Referral

Referral to a cardiologist is essential for advanced imaging and treatment planning. Consider involvement of haematology or rheumatology for systemic causes.

Patient Advice

Key advice includes:

• Take medications as prescribed and attend follow-up appointments regularly.
• Adopt a low-sodium diet and limit fluid intake to reduce symptoms of fluid retention.
• Engage in light exercise as tolerated and avoid overexertion.
• Report new or worsening symptoms, such as breathlessness or swelling, immediately.