Incidental Findings of Congenital Unileaflet Mitral Valves in Young Patient Presenting Complete Atrioventricular Block.

The singular leaflet mitral valve is a rare and complex entity that has been described in only a few case reports. It is commonly observed in infancy and combined with symptomatic mitral regurgitation (MR). In most asymptomatic individuals, this complication is attributed mainly to a hypoplastic posterior mitral leaflet and is usually revealed in adulthood. 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. Echocardiography 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 a unileaflet mitral valve that should be investigated even in adulthood as these patients are likely to be at risk of developing or worsening MR later in life; hence, performing periodic echocardiograms is important for detecting the progression of MR early.