A rare cause of mitral insufficiency: left atrial anomalous band.

Anomalous muscular bands have been seen in the left ventricle and right and left atria. Although the significance of left ventricular false tendons and right atrial anomalous muscular bands have been reported previously, the importance of anomalous muscular bands observed in the left atrium is not clearly defined. They have been found to be associated with Chiari's network, patent foramen ovale, and supraventricular arrhythmias. We describe a left atrial anomalous band causing mitral valve prolapse and mitral regurgitation.