Accessory mitral valve tissue (AMVT) is a rare congenital cardiac
anomaly, which is associated with other congenital heart diseases. It is
diagnosed in neonates or childhood and rarely in adulthood.
Nevertheless, AMVT is an incidental finding or described as isolated.
Echocardiography, especially three-dimensional(3D) echocardiography is
considered as an optimal imaging technique for AMVT diagnosis. We herein
presented the two asymptomatic adult cases with AMVT, who presented with
varying degrees of symptomatic left ventricular outflow tract (LVOT)
obstruction. One presented with mild LVOT obstruction and no surgery was
required, and another one with significant LVOT obstruction was
recommended for surgical excision.