Preoperative mitral valve annulus area size is an important factor in avoiding functional mitral stenosis after mitral valve repair.

Background: Functional mitral stenosis (FMS) following mitral valve (MV) repair for degenerative mitral regurgitation (DMR) is known as a poor prognostic factor. The parameters for avoiding postoperative FMS in MV repair for DMR have not been established.

Methods: Two-hundred-and-twenty patients (mean age 61.1 ± 13.3 years, 144 males) who underwent MV repair for DMR were analyzed. MV annulus area was measured pre- and postoperatively using three-dimensional transesophageal echocardiography (TEE). Trans-mitral pressure gradient (TMPG) was evaluated by postoperative transthoracic echocardiography and FMS was defined as a mean TMPG ≥ 5 mmHg.

Results: FMS was present in 14 patients (6.4%). Pre- versus postoperative MV annulus area change ratio was greater in the FMS group than in the non-FMS group (62.5 ± 7.2% vs. 48 ± 11.2%, p < 0.0001). On multivariate logistic regression analysis, MV annulus area change ratio was an independent predictor of FMS (odds ratio 1.19, 95% confidence interval 1.09-1.33, p < 0.0001), while receiver operating characteristics analysis showed that the optimal threshold for MV annulus area change ratio to predict FMS was 56.2% (area under the curve, 0.87; p < 0.0001).

Conclusion: The preoperative MV annulus area on TEE can be used to determine the postoperative MV annulus area to avoid FMS after MV repair.