The impact of patient–prosthesis mismatch on late outcomes after mitral valve replacement

Objectives The incidence of patient–prosthesis mismatch after mitral valve replacement and its effect on late outcomes have remained unclear. This study was conducted to determine the impact of patient–prosthesis mismatch on recurrent congestive heart failure, postoperative pulmonary hypertension, and late survival after mitral valve replacement. Methods Between 1985 and 2005, 884 patients, with a mean age 63 ± 12 years, underwent mitral valve replacement (657 mechanical, 227 bioprosthesis) with contemporary prostheses. Mean clinical and echocardiographic follow-up was 5.1 ± 4.1 years (4344 patient-years). Patient–prosthesis mismatch was defined as an indexed effective orifice area of 1.25 cm2 /m2 or less. Parametric and nonparametric analyses were used to determine predictors of outcomes. Results The incidence of patient–prosthesis mismatch was 32%. Predictors of recurrent congestive heart failure included low indexed effective orifice area, low ejection fraction, elevated postoperative mean mitral gradient, and use of a bioprosthesis ( P ≤ .05). Postoperative pulmonary hypertension was associated with small mitral size, elevated mean mitral gradient, low ejection fraction, and atrial fibrillation ( P ≤ .05); indexed effective orifice area did not predict postoperative pulmonary hypertension ( P = .89). Poor late survival was predicted by low indexed effective orifice area (≤1.25 cm2 /m2 ), New York Heart Association class 3 or 4, elevated right ventricular pressure, stroke, older age, coronary artery disease, and bioprosthesis use ( P ≤ .05). Survival for patients with patient–prosthesis mismatch versus those without patient–prosthesis mismatch at 1, 3, 5, and 10 years was 91% versus 95%, 85% versus 90%, 78% versus 86%, and 65% versus 75%, respectively ( P = .05). Conclusions Patient–prosthesis mismatch after mitral valve replacement is not uncommon; it is associated with recurrence of congestive heart failure and postoperative pulmonary hypertension and independently affected late survival. This study emphasizes the importance of implanting a sufficiently large prosthesis in adult patients undergoing mitral valve replacement.