Makindo Medical Notes

Related Subjects: |Dilated Cardiomyopathy |Hypertrophic cardiomyopathy (HCM - HOCM) |Peripartum cardiomyopathy |Restrictive Cardiomyopathy |Takotsubo Cardiomyopathy

⚠️ Restrictive cardiomyopathy carries a high risk of arrhythmias, embolic events, and sudden cardiac death. 👉 Always consider infiltrative diseases such as amyloidosis or haemochromatosis.

📖 About

• Restrictive cardiomyopathy (RCM) is characterised by stiff, non-compliant ventricles leading to impaired diastolic filling → "diastolic failure" with preserved systolic function.
• It is the least common cardiomyopathy but often has the worst prognosis because the underlying causes are progressive and systemic.

🧬 Aetiology

• Myocardial thickening, fibrosis, or infiltration causing reduced compliance.
• Common infiltrates include amyloid, iron, granulomas, and storage products (e.g. Fabry’s).

🔎 Causes

• Idiopathic or connective tissue diseases (rare).
• Post-radiotherapy fibrosis of myocardium.
• Infiltrative diseases:
  • Cardiac amyloidosis: "Granular sparkly" myocardium on echo, protein deposition in the interstitium.
  • Haemochromatosis: Iron overload damages conduction system and myocardium.
  • Sarcoidosis: Non-caseating granulomas causing arrhythmias and AV block.
  • Eosinophilic endomyocardial disease: Associated with hypereosinophilic syndromes, endocardial fibrosis.
  • Fabry’s disease: X-linked lysosomal storage disorder (deficiency of α-galactosidase A).
• Other rare causes:
  • Carcinoid syndrome (serotonin-mediated fibrosis).
  • Anthracycline chemotherapy cardiotoxicity.
  • Scleroderma (systemic sclerosis).

🩺 Clinical Features

• Right-sided heart failure predominates → peripheral oedema, ascites, hepatomegaly.
• Dyspnoea, reduced exercise tolerance, and fatigue from impaired LV filling.
• Atrial fibrillation is common (marked atrial dilatation).
• Raised JVP with steep x & y descents; may show Kussmaul’s sign (rise in JVP on inspiration).
• Extra heart sounds (S3), and a quiet apex beat.

🔀 Differential Diagnosis

• 🚩 Constrictive pericarditis — mimics RCM but potentially curable with pericardiectomy. Key difference: pericardial calcification on imaging, ventricular interdependence, pericardial knock on auscultation.

🔬 Investigations

• Bloods: FBC, U&E, LFTs, ESR. Iron studies if haemochromatosis suspected.
• ECG: Low-voltage QRS, nonspecific ST/T changes, possible arrhythmias.
• Echocardiography: Non-dilated ventricles, bi-atrial enlargement, preserved EF, abnormal diastolic filling. “Granular sparkly” myocardium in amyloidosis.
• Cardiac MRI: Helps distinguish RCM from constrictive pericarditis; can detect infiltration patterns.
• Serum amyloid P (SAP) scan: For amyloidosis staging.
• Endomyocardial biopsy: Gold standard for diagnosis if infiltrative disease suspected.

💊 Management

• Symptomatic: cautious diuretics for congestion, vasodilators to reduce filling pressures (avoid excess preload reduction as cardiac output may fall).
• Anticoagulation: indicated if AF or atrial dilatation → high embolic risk.
• Specific therapies:
  • Amyloidosis: tafamidis, chemotherapy for AL subtype.
  • Haemochromatosis: venesection or iron chelation.
  • Sarcoidosis: corticosteroids +/- immunosuppression.
  • Hypereosinophilic syndromes: cytotoxic therapy or steroids.
• Advanced therapies: cardiac transplant in selected cases.
• Prognosis: generally poor, as most causes are progressive systemic diseases.