Elongation of chordae tendineae as an adaptive process to reduce mitral regurgitation in functional mitral regurgitation

Aims In functional mitral regurgitation (FMR), increased leaflet area has been described as a remodelling compensatory mechanism. We hypothesized that chordae tendineae elongation would also occur as part of this remodelling. In this study, the lengths of primary chords and measurements of mitral leaflets and annulus were compared with varying degrees of mitral regurgitation (MR). Methods and results We studied 58 patients who underwent three-dimensional (3D) transoesophageal echocardiography, including 38 with FMR and 20 with normal mitral valves (NL). The FMR group was divided into two subgroups according to two-dimensional vena contracta width (VCW). Three-dimensional datasets from transgastric or mid-oesophageal approach were used to measure primary chordal length, coaptation length, inter-papillary muscle distances, and quantitative 3D measurements of the annulus and leaflets. Leaflet surface area was increased and coaptation length was decreased in FMR compared with NL. While no difference in other 3D measurement of annulus/leaflets was noted between the FMR subgroups, averaged chordal length was shorter in patients with more severe FMR. Chords of the anterior leaflet in FMR with larger VCW were shorter compared with both NL and FMR with smaller VCW. In contrast, the chords of the posterior leaflet were longer in FMR with smaller VCW compared with the other two groups. Conclusion Our results suggest the posterior leaflet chords possibly remodel by elongating and contribute to reduced MR and that in a subgroup of FMR patients, the primary chords may remodel by shortening, resulting in augmented MR. This information could be useful in choosing strategy for FMR correction.