HOCM: Features

Key points

• Autosomal dominant disorder of contractile protein genes — most commonly β-myosin heavy chain or myosin binding protein C · prevalence 1 in 500 (sibling risk 50%)
• Features: often asymptomatic · dyspnoea, angina, syncope · sudden death (most commonly ventricular arrhythmias), arrhythmias, heart failure
• Signs: jerky pulse · large 'a' waves · double apex beat · ejection systolic murmur that increases with Valsalva and decreases on squatting
• Echo mnemonic MR SAM ASH: mitral regurgitation · systolic anterior motion of the anterior mitral leaflet · asymmetric hypertrophy · associations: Friedreich's ataxia, Wolff-Parkinson White
• ECG: left ventricular hypertrophy · progressive T-wave inversion · deep Q waves · atrial fibrillation occasionally