HOCM: features

Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant disorder of muscle tissue caused by defects in the genes encoding contractile proteins. The most common defects involve a mutation in the gene encoding β-myosin heavy chain protein or myosin binding protein C. The estimated prevalence is 1 in 500.

Features

• often asymptomatic
• dyspnoea, angina, syncope
• sudden death (most commonly due to ventricular arrhythmias), arrhythmias, heart failure
• jerky pulse, large 'a' waves, double apex beat
• ejection systolic murmur: increases with Valsalva manoeuvre and decreases on squatting

Associations

• Friedreich's ataxia
• Wolff-Parkinson White

Echo - mnemonic - MR SAM ASH

• mitral regurgitation (MR)
• systolic anterior motion (SAM) of the anterior mitral valve leaflet
• asymmetric hypertrophy (ASH)

ECG

• left ventricular hypertrophy
• progressive T wave inversion
• deep Q waves
• atrial fibrillation may occasionally be seen

© Image used on license from Dr Smith, University of Minnesota