A 44-year-old man was referred for echo because of an asymptomatic murmur. This showed a gradient of 90 mm Hg in the left ventricular outflow tract (LVOT) with suggestion of a subaortic membrane and systolic anterior motion of the mitral valve. There was mild posteriorly directed mitral regurgitation.

Subsequent transoesophageal echo demonstrated a small accessory mitral valve leaflet attached to the upper …