Aetiology
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 |