Abstract 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 &lt; 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 &lt; 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 &lt; 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.

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