Long-term Clinical Impacts of Functional Mitral Stenosis After Mitral Valve Repair

Background. The relationship between functional mitral stenosis (MS) after mitral valve (MV) repair and long-term clinical outcomes is not fully understood. Therefore, we reviewed an institutional series to identify the determinants of functional MS and its effect on long-term clinical outcomes after MV repair for degenerative mitral regurgitation.Methods. Between January 1990 and December 2015, 792 patients who underwent MV repair for degenerative mitral regurgitation were retrospectively enrolled and divided into 2 groups: functional MS (n = 192) (>= 5 mm Hg mean diastolic pressure gradient across the MV) and nonfunctional MS (n = 600) (<5 mm Hg mean diastolic pressure gradient). Mean follow-up was 11.6 +/- 5.8 years.Results. After propensity-score matching, patients' characteristics were comparable between groups (n = 192/group). At 20 years, the functional MS group had significantly lower rates of freedom from new-onset atrial fibrillation (73.0% +/- 5.6% versus 93.2% +/- 2.3%; P = .003), overall survival (72.1% +/- 4.6% versus 85.6% +/- 4.3%; P = .010), and freedom from MV reoperation (82.8% +/- 4.1% versus 92.5% +/- 4.2%; P = .019) than the nonfunctional group. The functional MS group also had a significantly greater postoperative left atrial volume index and tricuspid regurgitation grade. A small left ventricular end-diastolic dimension (hazard ratio = 0.975; 95% confidence interval, 0.955-0.996; P = .022) and annuloplasty ring (hazard ratio = 0.757; 95% confidence interval, 0.685-0.837; P < .001) were independent risk factors for functional MS.Conclusions. A small left ventricle and annuloplasty ring increased the risk for functional MS after MV repair and was associated with progressive left atrial enlargement and tricuspid regurgitation exacerbation. As a result, functional MS increased the risk for new-onset atrial fibrillation, MV reoperation, and decreased long-term survival. (C) 2021 by The Society of Thoracic Surgeons