Prevalence of asymptomatic mitral valve malformations

Abstract

Congenital abnormalities of the mitral valve are considered to be very rare cardiac anomalies. In particular, more severe malformations, such as the complete absence of either aortic (anterior) or mural (posterior) mitral leaflet, are usually considered to be incompatible with life. Ebstein-like malformation of the mitral valve is an extremely rare form of mitral valve deformity hitherto unreported in an asymptomatic adult patient. The detection of such a malformation prompted us to perform a prospective analysis of 26,484 consecutive comprehensive 2D-echocardiographic examinations, conducted at our tertiary care university hospital between April 2007 and July 2008, with regard to the presence of malformations of the mitral valvular apparatus. In total, we found three cases of hypoplastic or even absent functional mural valve leaflets. All were diagnosed in adult patients who attended our outpatient department and were surprisingly asymptomatic regarding this finding. From our patient cohort, we calculate an actual prevalence of asymptomatic hypoplasia of the mitral valve of 1:8,800. Our findings broaden the spectrum of known mitral valve pathologies. The comparatively high prevalence of this malformation in our preselected patient cohort might indicate that this particular malformation has so far been under-diagnosed. In the context of this observation, both embryological development of the atrioventricular (AV) valves and recent functional insights into mitral valve physiology gained by mitral valve reconstructive surgery are discussed.