Incidence and predictors of mismatch after mechanical mitral valve replacement

Background Patient-prosthesis mismatch after mitral valve replacement has an unfavorable postoperative hemodynamic outcome, which underlines the importance of identifying and preventing prosthesis- and patient-related risk factors. This study was conducted to determine the incidence and identify possible predictors of patient-prosthesis mismatch. Methods A prospective study was conducted on 715 patients with a mean age of 42 ± 11 years who underwent mechanical mitral valve replacement between 2013 and 2017. The effective orifice area of the prostheses was estimated by the continuity equation, and a mismatch was defined as an effective orifice area index ≤1.2 cm 2 ·m −2 . The mean clinical and echocardiographic follow-up was 26.74 ± 11.58 months. Multivariate regression analysis was performed to identify predictors of patient-prosthesis mismatch. Results Patient-prosthesis mismatch was detected in 382 (53.4%) patients. A small mechanical prosthesis (<27 mm) was inserted in 54.3%. Mortality during follow-up was 9% (65 patients). Patient-prosthesis mismatch was identified in patients with preoperative rheumatic mitral valve pathology, associated tricuspid regurgitation, higher New York Heart Association class, preoperative atrial fibrillation, mitral stenosis, and small preoperative left ventricular dimensions. Multivariate analysis identified mitral stenosis, preoperative atrial fibrillation, and small postoperative left ventricular end-diastolic dimension as risk factors for patient-prosthesis mismatch. Conclusion Patient-prosthesis mismatch is a common sequela after mechanical mitral valve replacement. Identification of predictors of patient-prosthesis mismatch can help so that a preoperative strategy can be implemented to avoid its occurrence.