INTRODUCTION
Accessory mitral valve tissue (AMVT) is a rare cardiac anomaly in developing endocardial cushions. Frequently,it is associated with either simple or complex congenital heart disease, and rarely does it exist as an isolated lesion. Most symptoms occur when patients have a left ventricular outflow tract (LVOT) gradient of ≥50 mm Hg. Therefore, it is rare to discover an asymptomatic patient without LVOT obstruction. Accessory mitral valve tissue is usually diagnosed incidentally with complaints of chest pain, palpitations, dyspnea, and syncope in childhood.1-6 Surgical excision of isolated AMVT is required when there is significant obstruction of the LVOT and is associated with other cardiac abnormalities. Echocardiography provides important information about the morphology and hemodynamic significance of AMVT.6-8
Here, we present a patient with atrial septal defect (ASD) who was incidentally found to have AMVT on echocardiogram. Interestingly, the patient’s accessory mitral valve remained undetected for years until he became symptomatic.