• Autosomal dominant (♂=♀) aymmmetrical septal hypertrophy
  • Septal hypertrophy = obstruction but also SAM
  • SAM = Systolic Anterior Motion of the anterior leaflet of the mitral valve - the valve hits the hypertrophied septum
  • As pressure gradients ↑ (exercise) the obstruction worsens. Coronary vessels are filled during diastole ⇒ ischaemia ±arrhythmia


Presents as

Chest pain, palpitations or pre-syncope during excecise.

Ask about FHx of HOCM or sudden cardiac death.


Look for:

  • ↑JVP
  • S4 or split second heart sound
  • Crescendo-decrescendo systolic murmur (↑ with valsalva)
  • Mitral regurg. murmur
  • Resp. exam. normal


  • CXR not indicated - usually normal (rarely shows LVH)
  • ECG = LVH (any QRS in any lead >27mm)
  • May present as AF or VT
  • ECG often normal - Hx important
  • Dx in ED = ECHO (defintive = cardiac MRI as out patient)


  • If well, in sinus, discharge and GP to refer cardiology OPD
  • If AF or VT - call EM senior
  • Advise to avoid strenuous exercise until cardiology OPD
  • Avoid/stop nitrates/ACEI
  • Cardiology OPD may advise β-blockers ±surgery

Content by Dr Íomhar O' Sullivan 31/08/2018. Last review Dr ÍOS 3/06/21.