The strategy for mitral valve (MV) repair has recently focused on the restoration of the submitral apparatus. However, the relationship between geometric changes of the submitral apparatus and the mitral leaflets has not been systematically investigated. The aim of this study was to determine the relationships among chordal length (CL) and LV size and leaflet surface area (LSA) in normal subjects, patients with primary (degenerative) mitral regurgitation (PMR), and patients with functional (secondary) mitral regurgitation (FMR).

A total of 72 patients who underwent three-dimensional transesophageal echocardiography, including: 27 with PMR with isolated P2 flail leaflet, 25 with FMR with greater than mild mitral regurgitation, and 20 with normal mitral valves. LSA was quantified at midsystole from full-volume midesophageal views. CL was calculated by averaging the lengths of eight primary chords from transgastric full-volume data sets using multiplanar reconstruction.

Both CL and LSA in the PMR group were significantly longer compared with the FMR and normal control groups. No difference in CL was noted between patients with FMR and normal subjects. In all three groups, CL and LSA did not correlate with LV systolic or diastolic dimensions. Although CL did not correlate with LSA in the FMR group, a moderate correlation (R = 0.62) was observed in the PMR group.

In patients with FMR with greater than mild mitral regurgitation, the chords retain normal length, despite LSA and LV enlargement. In patients with PMR with flail P2 scallops, CL elongation of primary chords is associated with larger LSA but not with LV dimensions. This information may have implications for clinical strategies for mitral valve repair surgery, including the submitral approach and percutaneous procedures.