Annuloplasty Ring Size Determines Exercise-Induced Mitral Stenosis Severity after Valve Repair

Patients are occasionally encountered with high mitral pressure gradients after mitral valve repair for degenerative mitral regurgitation (MR), despite the use of a 'truesized' ring based on the anterior leaflet dimension. The study aim was to assess these patients at rest and during exercise, using echocardiography.

Sixty-seven patients who underwent mitral repair for degenerative disease using a semi-rigid, complete annuloplasty ring were assessed. A truesized ring was always selected for the annuloplasty. Of these patients, 20 were enrolled for exercise stress echocardiography. The indexed ring orifice area (iROA) was calculated by dividing the geometric orifice area of the annuloplasty ring by the patient's body surface area (BSA). Postoperatively, the patients were in sinus rhythm and had less than moderate MR.

During peak exercise, seven patients were considered to have severe mitral stenosis (MS), with a mean pressure gradient (mPG) >15 mmHg. The annuloplasty rings used in these seven patients were significantly smaller than those used in the other 13 patients (28.6 ± 1.9 mm versus 33.1 ± 3.1 mm; p = 0.003). The mPG at peak exercise was strongly correlated with the iROA (r = -0.767, p <0.001).

Mitral repair, even following the use of a true-sized ring, may be associated with severe MS when the ring size is relatively small for the patient's BSA. This association was shown to become more prominent during exercise.