Congenital accessory mitral valve tissue anomaly in a patient with genetically confirmed hypertrophic cardiomyopathy.

Accessory mitral valve tissue is a rare congenital cardiac anomaly that was initially described in children in association with other cardiac congenital abnormalities and, more recently, has also been reported in adults. The authors report a patient with genetically confirmed hypertrophic cardiomyopathy who also had a highly mobile, free-floating membrane-like structure in contiguity with the ventricular side of the anterior mitral valve leaflet, a feature consistent with the diagnosis of accessory mitral valve tissue.