Autosomal dominant genetic disorder characterised by left ventricular hypertrophy (LVH), impaired diastolic filling, and abnormalities of the mitral valve; it is the most common cause of sudden cardiac death in young people

Aetiology

• Hypertrophic cardiomyopathy is the most common genetic heart condition
• 60% of patients have an autosomal dominant mutation in sarcomeric genes

Pathophysiology

• Abnormal proteins cause septal hypertrophy which can result in left ventricular outflow tract obstruction and anterior movement of the mitral valve during systole
• Exercise raises the heart rate increasing ventricular contraction which exacerbates the obstruction
• A reduction in cardiac output and thus cerebral hypoperfusion leads to syncope
• Diastolic dysfunction and myocardial ischaemia also occurs

Clinical features

• Many cases are asymptomatic and are detected by family screening of an affected individual or by a routine ECG examination
• Sudden death occurs at any age but the highest rates occur in adolescents or young adults
• When present, clinical features include:
  • Exertional syncope
  • Shortness of breath
  • Chest pain
  • Palpitations (AF)
  • Heart failure
  • Double apex pulse
  • Ejection systolic murmur at the lower left sternal edge that may get louder during exercise and reduce if lying supine

Investigations

• ECG: may show a variety of changes including LV hypertrophy, ST and T wave changes, and abnormal Q waves
• Echocardiography: is usually diagnostic, can demonstrate septal hypertrophy
• Cardiac MRI: can measure the extent of left ventricular hypertrophy
• Genetic testing

Management

• Patients with 2 or more risk factors for sudden cardiac death should be assessed for ICD insertion
  • RF include massive LH hypertrophy, prior unexplained syncope and family history of sudden cardiac death