Restrictive Cardiomyopathy

Restrictive cardiomyopathy (RCM) is characterised by impaired ventricular filling from stiff myocardium, with normal or reduced volumes, near normal wall thickness (unless infiltrative) and preserved or mildly reduced systolic function.

• Rare. Causes:
  • Infiltrative: amyloidosis (commonest), sarcoidosis.
  • Storage: haemochromatosis, Fabry disease, Gaucher disease, glycogen storage.
  • Noninfiltrative: idiopathic, familial (troponin I, desmin, filamin C), scleroderma, diabetic.
  • Endomyocardial: endomyocardial fibrosis (tropical regions), hypereosinophilic syndrome (Löffler endocarditis), carcinoid heart disease, radiation, anthracyclines.
• Prognosis is poor in children and in amyloid disease; 5 year survival is about 50 to 60%.

• Predominantly right sided heart failure: raised jugular venous pressure with Kussmaul sign (paradoxical rise on inspiration), hepatomegaly, ascites, peripheral oedema.
• Exertional dyspnoea, fatigue, exercise intolerance, low cardiac output.
• Atrial fibrillation, thromboembolism, conduction disease, syncope.
• Features of the cause: macroglossia, periorbital purpura, neuropathy (amyloid), skin pigmentation (haemochromatosis), eosinophilia.

• Echocardiography: biatrial enlargement, normal ventricular size, restrictive filling (E/A over 2, short deceleration time, E/e' over 15), reduced longitudinal strain with apical sparing (amyloid).
• Cardiac MRI: tissue characterisation, late gadolinium enhancement, T2* for iron overload, T1 mapping.
• Distinguish from constrictive pericarditis: respiratory variation of mitral inflow (over 25%), septal bounce, preserved annular e' with annulus reversus, pericardial thickening or calcification on CT and MRI, ventricular interdependence at catheterisation.
• Laboratory: serum and urine protein electrophoresis with immunofixation and free light chains, troponin, NT proBNP, ferritin, ACE, eosinophil count.
• Technetium pyrophosphate scintigraphy for transthyretin amyloid; endomyocardial biopsy when needed.

• Treat the underlying cause: see cardiac amyloidosis, sarcoidosis, haemochromatosis (venesection or deferasirox 20 to 30 mg/kg), hypereosinophilia (prednisolone 1 mg/kg, imatinib 100 to 400 mg), Fabry (agalsidase beta 1 mg/kg every 2 weeks, migalastat 123 mg alternate days).
• Diuretics: furosemide 40 to 120 mg with spironolactone, cautiously to avoid reduced preload and low output.
• Rate control for atrial fibrillation with cautious beta blockers; avoid digoxin and nondihydropyridine calcium channel blockers in amyloid. Amiodarone for rhythm control.
• Anticoagulation for atrial fibrillation and intracardiac thrombus (apixaban 5 mg twice daily or warfarin), irrespective of score in amyloid.
• Pacemaker for symptomatic bradycardia; ICD in selected cases.
• Avoid ACE inhibitors and beta blockers in advanced amyloid with hypotension.
• Endomyocardial fibrosis: surgical decortication with valve repair or replacement.
• Cardiac transplantation for refractory idiopathic or familial RCM; combined heart and liver or stem cell transplant in selected amyloid.