Restrictive Cardiomyopathy
Related Subjects:
|Dilated Cardiomyopathy
|Hypertrophic cardiomyopathy (HCM - HOCM)
|Peripartum cardiomyopathy
|Restrictive Cardiomyopathy
|Takotsubo Cardiomyopathy
โ ๏ธ Restrictive cardiomyopathy carries a high risk of arrhythmias, embolic events, and sudden cardiac death.
๐ Always consider infiltrative diseases such as amyloidosis or haemochromatosis.
๐ About
- Restrictive cardiomyopathy (RCM) is characterised by stiff, non-compliant ventricles leading to impaired diastolic filling โ "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.
๐งฌ Aetiology
- Myocardial thickening, fibrosis, or infiltration causing reduced compliance.
- Common infiltrates include amyloid, iron, granulomas, and storage products (e.g. Fabryโs).
๐ 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.
- Fabryโs disease: X-linked lysosomal storage disorder (deficiency of ฮฑ-galactosidase A).
- Other rare causes:
- Carcinoid syndrome (serotonin-mediated fibrosis).
- Anthracycline chemotherapy cardiotoxicity.
- Scleroderma (systemic sclerosis).
๐ฉบ Clinical Features
- Right-sided heart failure predominates โ 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 Kussmaulโs sign (rise in JVP on inspiration).
- Extra heart sounds (S3), and a quiet apex beat.
๐ Differential Diagnosis
- ๐ฉ Constrictive pericarditis โ mimics RCM but potentially curable with pericardiectomy.
Key difference: pericardial calcification on imaging, ventricular interdependence, pericardial knock on auscultation.
๐ฌ 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. โGranular sparklyโ 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.
๐ 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 โ 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.
