Cardiomyopathy is a term used to describe a heart muscle disorder, without an other obvious cardiac abnormality. The European Heart Journal describes it as a:
myocardial disorder in which heart muscle is structurally and functionally abnormal without coronary artery disease, hypertension, valvular or congenital heart diseases.
However, sometimes cardiomyopathy is a result other cardiac disease, such as hypertension, valvular disorders or ischaemic heart disease.
There are many types of cardiomyopathy, with varying prognoses, from asymptomatic to severe life-limiting and life-threatening. Some types are associated with sudden cardiac death.
- Cardiomyopathies can at a younger age than most other cardiac diseases
- Suspect cardiomyopathy in any patient presenting with heart failure
- Hypertrophic cardiomyopathy is the most common cause of unexpected death in childhood
- Often a genetic component – especially for hypertrophic cardiomyopathy – in which 50% of cases have a family history
Classification and causes
Cardiomyopathies can be primary (idiopathic) and secondary. Secondary causes include:
- Connective tissue disorders – e.g. sarcoidosis, SLE
- Endocrine disorders – e.g. diabetes, thyroid disease, acromegaly
- Drugs – e.g. chemotherapeutic agents, cocaine, alcohol
- Nutrition – obesity, some specific deficiencies – e.g. vit B1, calcium, magnesium
- Genetic causes – e.g. duchenne muscular dystrophy
Clinically, we divide cardiomyopathies into 4 types:
- Dilated cardiomyopathy
- Hypertrophic cardiomyopathy
- Restrictive cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
The most common type of cardiomyopathy. It is characterised by enlarged ventricular size, with normal ventricular wall thickness. Usually affects the left or both ventricles. It is the most common reason for heart transplant.
- Affects about 2 in 10,000
- Often in a genetically susceptible individual
- Typically presents in adults aged 20-60
- More common in men
- More common in Africans
Identifying an underlying cause is difficult. Patients often have multiple risk factors.
- Ischaemic heart disease
- Thyroid disorder
- Valvular disease
- Genetic causes
- Sometime idiopathic
Arrhythmogenic right ventricular cardiomyopathy (ARVC)
- Ischaemic heart disease
- Valvular heart disease – particularly of the mitral and aortic valves
- May produce some findings consistent with a cardiomyopathy, when in fact none is present
- Pulmonary stenosis
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.