Hypertrophic Obstructive Cardiomyopathy (HOCM)

Septal hypertrophy often causing Left Ventricular outflow tract (LVOT) obstruction.


Symptoms: LVF including breathlessness etc., syncope, chest pain, AF and sudden death.



  • Jerky pulse
  • May have AF
  • Large A waves in the JVP or normal
  • Patient may have ICD in situ.
  • Auscultation:
    • Dynamic* ejection systolic murmur radiating to the apex.
    • Loud or normal S1
    • S4 may be present.
    • Signs of LVF
    • May develop MR and pansystolic murmur as a result of systolic anterior motion of the anterior leaflet of the mitral valve, caused by rapid blood flow in the LVOT.


*Dynamic refers to the change in severity of the murmur with posture or action. Certain actions increase the severity of the murmur by decreasing vascular resistance and increasing the peak pressure difference (PPD) across the LVOT (valsalva manoeuvre, standing). Other actions decreasing the murmur by increasing vascular resistance (Squatting, hand grip release of valsalva manoeuvre).


Causes: Genetic (AD) in 50% of patients.



ECG: can show: LVH, lateral t-wave inversion, p-mitrale and deep septal (v3-4) q-waves.

Echo: To diagnose the hypertrophy and assess severity of LVOT

Holter monitor: To monitor for ventricular arrhythmias (increased risk of sudden death).

Exercise tolerance test: To assess for BP response to exercise. If BP does not rise with exercise as expected it suggests a worse LVOT obstruction.




Patients at risk of sudden death should be offered an ICD. Sudden death risk factors:

  • FHx of sudden death
  • PMH of arrhythmic cardiac arrest
  • Episode of sustained or even non-sustained VT (sustained giving greater risk)
  • Abnormal BP response to exercise
  • LVH >30mm wall thickness
  • Unexplained syncope


Medical treatment is acceptable of none of the above risk factors are present. This includes treatment to improve myocardial relaxation and perfusion such as rate limiting with beta blockers or verapamil.


Patients with a large LVOT obstruction:

  • Betablockers block the effect of catecholamines on the LVOT gradient. Disopyramide is often used as adjunctive therapy to aid this.
  • Patients with dyspnoea refractory to medical treatment and NYHA III/IV symptoms should be offered wither alcohol septal ablation or surgical myomectomy.


Patients’ family members should be screened for HOCM.



Written by Dr Thomas Craven


Resources used to write this document are listed in the references section of this webpage