Obstructive HCM is characterized by diastolic dysfunction, dynamic LVOT obstruction and rhythm troubles with risk of sudden death [11]. Generally speaking, the LVOT obstruction is often caused by the basal septum hypertrophy. Moreover, SAM of the mitral valve could result in mitral–septal apposition and incomplete leaflet apposition. As an important phenomenon in the mechanism of pathology, SAM may be caused by, as well as aggravate, the obstruction of LVOT, and would result in mitral valve apparatus distortion and MR. In this group, SAM was present in 100% of the patients preoperatively. Besides, anomalous papillary muscles can also contribute to MR and midcavity obstruction, usually by direct insertion into the mitral valve leaflets [12].