Cardiomyopathy

Background

  • Disease of the myocardium, classified by structural and functional presentation
    • e.g.
  • Can be inherited or have infective, toxic or idiopathic causes

Dilated Cardiomyopathy

Background

  • Characterised by dilation and impaired contraction of the LV (often also RV)
    • LV mass is increased but wall thickness is normal/reduced
    • Dilation can lead to functional mitral/tricuspid incompetence
  • Most frequent cause of heart transplant and occurs in around 20/100,000; Men more commonly affected (2:1)
    • Genetic component in 30-50% (at least 25% autosomal dominant- most commonly mutations in cytoskeleton proteins e.g. dystrophin); usually occurs between 40-50 (more common in Afro-Caribbeans)
    • May be associated with muscular dystrophies
    • Many are thought to be caused by a late autoimmune response to viral myocarditis (similarly, myocarditis seen in patients with HIV)

Presentation

  • Most present with heart failure
    • Dyspnoea, fatigue, angina, palpitations
    • Oedema, crackles, raised JVP, displaced apex beat, hypotension, mitral regurgitation (systolic murmur)
  • Sudden onset arrythmia, thromboembolism and sudden death can occur

Investigations

  • ECG may show non-specific changes e.g. sinus tachycardia, LBBB, nonspecific T wave inversions/ST segment changes
  • Echocardiography is diagnostic (alternatively MRI)
  • CXR may show pulmonary oedema

Management

  • Control heart failure i.e. beta-blockers and angiotensin receptor blockers/ACE inhibitors
  • Diuretics to control any oedema
  • Consider implantable defibrillator/cardiac resynchronisation therapy
  • Heart transplant in severe, refractory disease

Hypertrophic cardiomyopathy

Background

  • Most common form (prevalence of around 0.1%)
  • Characterised by abnormal LVH  with malalignment of cardiac fibres and myocardial fibrosis
    • Can be generalised or localised (most commonly to the IV septum)
  • Predominantly genetic (autosomal dominant condition- mutations of sarcomere contractile proteins e.g. beta myosin (most severe); troponin (least severe- often asymptomatic; and myosin-BP C (presents later in life))
  • Heart failure is caused by impairment of heart function due to rigid non-compliant ventricular filling.  Septal hypertrophy can also cause partial outflow obstruction and mitral regurgitation

Presentation

  • Most present with hypertension, exertional angina/dyspnoea/pre-syncope; again, arrhythmia and sudden death can also present
    • Troponin type may actually present with exertional hypotension
    • Sudden death/arrhythmias typically occur after exertion (this is often the case in young/fit people)
  • Jerky pulse; displaced/palpable (often double impulse) apex beat; mid-systolic murmur at the base or pansystolic murmur at apex

Investigation

  • ECG
    • LVH (see here– same as aortic stenosis) often with unusual deep T wave inversions
  • Echo may be diagnostic but cannot differentiate between physiological enlargement and pathological enlargement
    • Where there is any doubt, consider genetic testing

Management

  • Beta blockers and rate limiting CCB e.g. verapamil
  • Arrhythmias should be managed appropriately (often respond to amiodarone)
  • Outflow tract obstruction can be managed surgically or radiologically by injection of alcohol solution
  • Implantable defibrillator
  • NB AVOID DIGOXIN AND VASODILATORS (can increase outflow obstruction)

Arrhythmogenic right ventricular cardiomyopathy

  • Autosomal dominant condition characterised by the replacement of parts of the right ventricular myocardium with fibrous and fatty tissue. (Uncommon 1:2000)
  • These patients are at increased risk of ventricular arrhythmias, sudden death (serious cause of sudden death in <35 year group- and accounting for around 20% of sudden cardiac deaths) and right heart failure
  • Can present with symptoms of arrhythmia e.g. syncope, palpitationsECG may show a slightly broad QRS complex and inverted T waves in the right precordial leads (II < III; V1 > V2)
    • Echo and MRI to confirm
  • Implantable defibrillator is an option for patients at risk of sudden death (drug treatments such as sotalol or amiodarone + beta blocker may help.

Restrictive Cardiomyopathy

  • Rare ventricular filling defect due to stiff ventricles, leading to high atrial pressures and atrial hypertrophy, dilation and later atrial fibrillation.
    • Most common cause in the UK is amyloidosis (other causes include idiopathic, infiltrative disease, sarcoid, rarely haemochromatosis) – most patients are elderly
  • Most present with symptoms of heart failure with normal systolic function
    • Right heart failure predominates i.e. raised JVP, hepatomegaly, oedema, ascites
  • Diagnosis is with Doppler echo, MRI and often biopsy.
  • Many patients require transplant, although symptomatic treatment should be given prior to this e.g. ACE inhibitor, beta blocker, non-dihydropyridine CCBs and diuretics
    • Myopathy due to amyloidosis has a poor prognosis even with transplantation
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