5th July 2026

Diagnosis

Signs and symptoms

Patients with RCM may be asymptomatic or present with symptoms of:

angina
cardiac failure: shortness of breath on exertion, orthopnoea, fatigue, paroxysmal nocturnal dyspnoea, abdominal discomfort, or leg swelling

Clinical signs that may be elicited on examination include:

bilateral basal crackles on lung auscultation
hepatomegaly
jugular venous distension
peripheral oedema
S3 gallop during rapid ventricular phase of diastole, indicating ventricular dilatation
low pulse volume and faster pulse: in advanced phases

Other factors to consider in the history and examination include:

Patients typically display signs and symptoms of heart failure with preserved ejection fraction (HFpEF)

Carpal tunnel syndrome, lumbar spinal stenosis, aortic stenosis, skin bruising, proteinuria (cardiac amyloidosis)
Erythema nodosum, lupus pernio (sarcoidosis)
Bronze skin pigmentation, diabetes mellitus, arthralgia, chronic liver disease (haemochromatosis)
Gait disturbance (Friedrich’s ataxia)
Learning difficulties, visual impairment (Danon disease)
Proteinuria, angiokeratoma, peripheral neuropathy (Anderson-Fabry disease)
Three-generation family history

Investigations

Investigations	Description
Bloods and urine testing	First line: Full blood count, urea and electrolytes, creatine kinase, liver function, serum iron, ferritin, bone profile, phosphate, magnesium, thyroid function, troponin, NT-proBNP, urine and serum protein electrophoresis, immunoglobulins, serum free light chains, proteinuria Second line: serum angiotensin-converting enzyme (ACE), organ-specific serum autoantibodies, alpha-galactosidase A
Electrocardiogram	Atrial fibrillation Short PR interval Atrioventricular block Ventricular arrhythmias Supraventricular tachycardia Low QRS complexes, pseudoinfarct pattern (cardiac amyloidosis)
Echocardiogram	LV and RV anatomy and function Bi-atrial enlargement and interatrial septal thickening Valvular involvement Restrictive pattern of transmitral flow: elevated early diastolic filling velocity (E wave) and decreased atrial filling velocity (A wave) Raised E/e’ ratio due to reduced early diastolic myocardial velocity (e’)
Cardiac MRI	Aetiological definition of cardiomyopathy through tissue characterisation (T1- and T2 mapping sequence, late gadolinium enhancement, extracellular volume mapping), chamber volume and function. Define presence of myocardial fibrosis.
Nuclear medicine scan	F18 fluorodeoxyglucose (18F-FDG)-positron emission tomography-cardiac tomography (PET-CT) when cardiac sarcoidosis is suspected. ^99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) if suspecting transthyretin (ATTR)-related cardiac amyloidosis.
Endomyocardial biopsy	Should be pursued to exclude specific diagnoses (including haemochromatosis, sarcoidosis, storage disease, etc.) and to diagnose restrictive myofibrillar disease caused by desmin variants.
Genetic testing	Mostly autosomal dominant pattern of inheritance Most common pathological gene involved encodes the thin filament troponin I Identifies pathogenic variants in TTR gene

Table 3: Investigations for RCM

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