Cardiomyopathy
D E FI N I T ION
Primary disease of the myocardium. Cardiomyopathy may be dilated, hypertrophic
or restrictive.
AETIOLOGY
The majority are idiopathic.
Dilated:
Post-viral myocarditis, alcohol, drugs (e.g. doxorubicin, cocaine), familial (25% of
idiopathic cases, usually autosomal dominant), thyrotoxicosis, haemochromatosis,
peripartum.
Hypertrophic:
Up to 50% of cases are genetic (autosomal dominant) with mutations in
b-myosin, troponin T or a-tropomyosin (components of the contractile apparatus).
Restrictive:
Amyloidosis, sarcoidosis, haemochromatosis.
EPIDEMIOLOGY
Prevalence of dilated cardiomyopathy and hypertrophic cardiomyopathy
is 0.05–0.20%. Restrictive cardiomyopathy is rare.
HISTORY
Dilated:
Symptoms of heart failure, arrhythmias, thromboembolism, family history of sudden
death.
Hypertrophic:
Usually none. Syncope, angina, arrhythmias, family history of sudden death.
Restrictive:
Dyspnoea, fatigue, arrhythmias, ankle or abdominal swelling.
Enquire about family history of sudden death.
EXAMINATION
Dilated:
" JVP, displaced apex beat, functional mitral and tricuspid regurgitations, third heart
sound.
Hypertrophic:
Jerky carotid pulse, double apex beat, ejection systolic murmur.
Restrictive:
" JVP (Kussmaul’s sign: further " on inspiration), palpable apex beat, third heart
sound, ascites, ankle oedema, hepatomegaly.
INVESTIGATIONS
CXR:
May show cardiomegaly, and signs of heart failure.
ECG:
All types:
Non-specific ST changes, conduction defects, arrhythmias
Hypertrophic:
Left-axis deviation, signs of left ventricular hypertrophy (see Aortic stenosis), Q
waves in inferior and lateral leads.
Restrictive:
Low voltage complexes.
Echocardiography:
Dilated:
Dilated ventricles with ‘global’ hypokinesia.
Hypertrophic:
Ventricular hypertrophy (disproportionate septal involvement)
Restrictive:
Non-dilated non-hypertrophied ventricles. Atrial enlargement, preserved systolic
function, diastolic dysfunction, granular or ‘sparkling’ appearance of myocardium in
amyloidosis.
Cardiac catheterization:
May be necessary for measurement of pressures.
Endomyocardial biopsy:
May be helpful in restrictive cardiomyopathy.
Pedigree or genetic analysis: Rarely necessary.
MANAGEMENT
Dilated:
Treat heart failure and arrhythmias. Consider implantable cardiac defibrillators (ICD)
for recurrent VTs.
Hypertrophic:
Treat arrhythmias with drugs, ICD for survivors of sudden death, reduce
outflow tract gradients, pacemaker, surgery (e.g. septal myomectomy, septal ablation
with ethanol). Screen family members with ECG or echocardiography.
Restrictive:
No specific treatment. Manage the underlying cause.
Cardiac transplantation:
May be considered in end-stage heart failure in all cardiomyopathy
types.
Cardiomyopathy (continued)
COMPLICATIONS
Heart failure, arrhythmias (atrial and ventricular).
Dilated and hypertrophic cardiomyopathy:
Sudden death and embolism.
Hypertrophic:
Infective endocarditis.
PROGNOSIS
Dilated:
Depends on the aetiology, New York Heart Association functional class and ejection
fraction.
Hypertrophic:
Ventricular tachyarrhythmias are the major cause of sudden death.
Restrictive:
Poor prognosis, many die within the first year after diagnosis.
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