Echocardiographic assessment of the mechanisms of correction of bileaflet prolapse causing mitral regurgitation with only posterior leaflet repair surgery.

Recent data suggest that posterior leaflet repair alone corrects mitral regurgitation in patients with bileaflet prolapse and normal anterior chordae. The purpose of this study was to use echocardiography to define the anatomic differences between posterior and bileaflet prolapse and to determine if posterior leaflet repair alone leads to correction of bileaflet prolapse. We studied patients who underwent quadrangular resection of the posterior mitral valve leaflet to treat bileaflet prolapse (group I, n = 20) or isolated posterior leaflet prolapse (group II, n = 20). Echocardiographic characteristics were compared before and after the procedure. There were no differences in the left ventricular end-diastolic or end-systolic dimensions or function between the 2 groups. However, anterior leaflet length was greater in patients with bileaflet prolapse (3.3 +/- 0.6 cm vs 2.6 +/- 0.4 cm, p = 0.003). In group I, posterior leaflet repair changed anterior leaflet displacement from -0.8 +/- 0.2 to 0.5 +/- 0.4 cm (p <0.001) and posterior leaflet displacement from -0.8 +/- 0.3 cm below to 0.5 +/- 0.4 cm (p <0.001) in front of the mitral annular plane. In group II, anterior leaflet displacement was unchanged from 0.2 +/- 0.1 to 0.3 +/- 0.2 cm (p = 0.22), whereas posterior leaflet displacement changed from -0.7 +/- 0.2 to 0.4 +/- 0.2 cm (p <0.001). Thus, patients with bileaflet prolapse and no ruptured chords have excessive anterior leaflet length. In such patients, posterior leaflet repair alone corrects anterior and posterior leaflet prolapse.