Patient-Prosthesis Mismatch After Mitral Valve Replacement: A Propensity Score Analysis

Background. We evaluated the impact of patient-prosthesis mismatch (PPM) after mitral valve replacement on the clinical outcomes using propensity score models. Methods. In all, 760 patients (aged 51 +/- 12 years; male: female = 252: 508) in whom mitral valve replacement was performed using three types of mechanical valves and two types of bioprosthetic valves were enrolled. In vivo data of effective orifice area was drawn from literatures and mitral PPM was defined as an effective orifice area index 1.2 cm(2)/m(2) or less. The propensity score model was used in two ways: the inverse probability of treatment weighting-adjusted multivariable analyses, and 1: 1 propensity score matching. The duration of the follow-up was 127 months (range, 1 to 276). Results. Mitral PPM was identified in 19.3%. The patients with PPM (PPM group, n = 147) were older and had more comorbidities than the patients without PPM (non-PPM group, n = 613). The 10-year and 20-year overall survival and freedom from cardiac death were 83.5% and 71.3%, respectively, for the PPM group; and 90.2% and 83.1%, respectively, for the non-PPM group. The inverse probability of treatment weighting-adjusted multivariable analyses demonstrated that mitral PPM is a significant risk factor for overall survival (hazard ratio 1.681, 95% confidence interval: 1.139 to 2.482) and freedom from cardiac death (hazard ratio 1.673, 95% confidence interval: 1.012 to 2.765). The propensity score matching extracted 68 pairs. Both overall survival and freedom from cardiac death were also higher in the propensity score-matched non-PPM group than in the PPM group (p = 0.039 and p = 0.017, respectively). Conclusions. Mitral PPM significantly affects long-term outcomes after mitral valve replacement in terms of long-term survival and freedom from cardiac death. (C) 2016 by The Society of Thoracic Surgeons