Fast Diastolic Swinging Motion of the Mitral Valve as a Clinical Marker of Familial Hypertrophic Cardiomyopathy in Genetically Affected Young Children without Left Ventricular Hypertrophy: A New Role for Noninvasive Imaging?

Structural mitral valve (MV) abnormalities are common in patients with hypertrophic cardiomyopathy (HCM). This is the first report demonstrating MV abnormalities in very young children as the sole overt clinical feature of a known HCM‐causing sarcomere protein gene mutation. Due to MV leaflet elongation, we also noticed a typical fast diastolic swinging motion of the MV in our patients. This novel echocardiographic feature may be used as a clinical marker of HCM disease in the absence of left ventricular hypertrophy.