Aetiology
The old classification of dilated, restricted and hypertrophic cardiomyopathy has been largely abandoned due to the high degree of overlap. The latest classification of cardiomyopathy by the WHO and American Heart Association reflect this.
The tables below shows a very limited set of exam related facts for the various cardiomyopathies:
Primary cardiomyopathies - predominately involving the heart
Genetic - both conditions listed below are autosomal dominant. An implantable cardioverter-defibrillator is often inserted to reduce the incidence of sudden cardiac death.
Mixed - rather confusingly most of the causes of dilated and restrictive cardiomyopathy are now listed separately in the 'secondary' causes. This category servers as a reminder that many patients will have a genetic predisposition to cardiomyopathy which is then triggered by the secondary process, hence the 'mixed' category
Secondary cardiomyopathies- pathological myocardial involvement as part of a generalized systemic disorder
The tables below shows a very limited set of exam related facts for the various cardiomyopathies:
Primary cardiomyopathies - predominately involving the heart
Genetic - both conditions listed below are autosomal dominant. An implantable cardioverter-defibrillator is often inserted to reduce the incidence of sudden cardiac death.
| Type of cardiomyopathy | Selected points |
|---|---|
| Hypertrophic obstructive cardiomyopathy | Leading cause of sudden cardiac death in young athletes Usually due to a mutation in the gene encoding β-myosin heavy chain protein Common cause of sudden death Echo findings include MR, systolic anterior motion (SAM) of the anterior mitral valve and asymmetric septal hypertrophy |
| Arrhythmogenic right ventricular dysplasia | Right ventricular myocardium is replaced by fatty and fibrofatty tissue Around 50% of patients have a mutation of one of the several genes which encode components of desmosome ECG abnormalities in V1-3, typically T wave inversion. An epsilon wave is found in about 50% of those with ARV - this is best described as a terminal notch in the QRS complex |
Mixed - rather confusingly most of the causes of dilated and restrictive cardiomyopathy are now listed separately in the 'secondary' causes. This category servers as a reminder that many patients will have a genetic predisposition to cardiomyopathy which is then triggered by the secondary process, hence the 'mixed' category
| Type of cardiomyopathy | Selected causes/points |
|---|---|
| Dilated cardiomyopathy | Classic causes include
|
| Restrictive cardiomyopathy | Classic causes include
|
Acquired
| Type of cardiomyopathy | Selected points |
|---|---|
| Peripartum cardiomyopathy | Typical develops between last month of pregnancy and 5 months post-partum More common in older women, greater parity and multiple gestations |
| Takotsubo cardiomyopathy | 'Stress'-induced cardiomyopathy e.g. patient just found out family member dies then develops chest pain and features of heart failure Transient, apical ballooning of the myocardium Treatment is supportive |
Secondary cardiomyopathies- pathological myocardial involvement as part of a generalized systemic disorder
| Type of cardiomyopathy | Selected causes/points | |
|---|---|---|
| Infective | Coxsackie B virus Chagas disease | |
| Infiltrative | Amyloidosis | |
| Storage | Haemochromatosis | |
| Toxicity | Doxorubicin Alcoholic cardiomyopathy | |
| Inflammatory (granulomatous) | Sarcoidosis | |
| Endocrine | Diabetes mellitus Thyrotoxicosis Acromegaly | |
| Neuromuscular | Friedreich's ataxia Duchenne-Becker muscular dystrophy Myotonic dystrophy | |
| Nutritional deficiencies | Beriberi (thiamine) | |
| Autoimmune | Systemic lupus erythematosis |