Incidental Finding of Congenital Unileaflet Mitral Valve in a Young Patient Presenting with Complete Atrioventricular Block

Abstract Singular leaflet mitral valve is rare and complex entity that has only been described in a few case reports. It is commonly observed in infancy and combined with symptomatic mitral regurgitation (MR). In most asymptomatic individuals, it is mainly attributed to hypoplastic posterior mitral leaflet and is usually revealed in adulthood by a complication. We present the case of a 30-year-old man who presented with chest pain and dyspnea for two days. The electrocardiogram showed complete atrioventricular block with a beat rate of 30 bpm. Echocardiogram revealed an elongated anterior mitral valve leaflet and an almost completely absent posterior mitral valve leaflet with no MR. Our case is unusual presentation of unileaflet mitral valve which should be investigated even in adulthood as these patients are likely to be at risk of developing or worsening MR later in life, hence, the importance of performing periodic echocardiograms in these patients in order to detect the progression of MR early.