Cardiomyopathy

“A general term for diseases of the heart muscle, where the walls of the heart chambers have become thickened, stiff, or stretched.”

• Forms of Cardiomyopathy:
  • Hypertrophic Cardiomyopathy (HC)
  • Restrictive Cardiomyopathy (RC)
  • Dilated Cardiomyopathy (DC)
  • Broken Heart Syndrome (Takotsubo Cardiomyopathy, TC)

Risk Factors

• Uncontrolled high blood pressure
• Alcohol and recreational drugs
• Heart valve problem
• Diseases of the tissues or blood vessels (sarcoidosis, amyloidosis, lupus, polyarteritis nodosa, vasculitis or muscular dystrophy)

Aetiology

• HC – Autosomal Dominant Genetic Mutation in one of the 12 genes that are important for heart development
• RC – Usually autosomal dominant inheritance, but autosomal recessive, X-linked and mitochondrial-transmitted disease occurs
• DC – 50% Familial Dilated Cardiomyopathy (FDCM) – Autosomal Dominant, 50% varied inheritance
• TC – Not inherited. Excess of the stress hormone adrenaline caused by emotional or physical distress (e.g. bereavement, domestic abuse, physical assault or recent surgery)

Pathophysiology

• HC:
  1. Mutation in the sarcomere
  2. Instigates a series of proximal defects (e.g. altered ATPase activity)
  3. Molecular changes induce histological and morphological changes  
  4. Myocyte hypertrophy and fibrosis
  5. Reduced ventricular volume
• RC:
  1. Cardiomyocytes replaced with abnormal scar tissue
  2. ventricular stiffness
  3. Contraction unaffected however filling is ↓
  4. ↓ CO
  5. Reduced ventricular filling causes atria dilation
• DC:
  1. Primary cardiomyopathic process
  2. ↓ Systolic function caused by myocardial remodelling
  3. ↑ End-systolic / end-diastolic volumes
  4. Progressive dilatation
  5. Significant tricuspid and mitral valve insufficiency
  6. Further lowers the ejection fraction
• TC – Precise cause is unknown:
  1. Likely, surging stress hormones (esp. adrenaline) “stun” the heart
  2. Triggering changes in cardiomyocytes and coronary blood vessels
  3. Prevent effective LV contraction.
  4. REVERSIBLE

Clinical Presentation

• HC – Dizziness, Chest pain, SOB, & Syncope
  • The most common cause of sudden unexpected death in childhood and in young athletes
• RC – Similar to HF – SOB, Oedema, Fatigue, Rhythm problems
• DC – Similar to HF – SOB, Oedema, Fatigue, Palpitations
• TC – Similar to a heart attack – Chest pain, SOB, N&V

Investigations

• Bloods: n/a
• Imaging:
  • MRI
  • Echocardiogram
• Special:
  • ECG
  • 24 or 48-hour ECG monitor
  • Exercise test
  • A detailed family tree may be required for the diagnosis of a familial cardiomyopathy

Management

• There’s usually no cure for cardiomyopathy, but the treatments can be effective at controlling symptoms and preventing complications
• Most commonly used medications are: ACE inhibitors, angiotensin receptor blockers, beta-blockers and warfarin

Complications

• Heart failure
• Heart valve regurgitation
• Sudden cardiac arrest