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 < or = .05). Postoperative pulmonary hypertension was associated with small mitral size, elevated mean mitral gradient, low ejection fraction, and atrial fibrillation (P < or = .05); indexed effective orifice area did not predict postoperative pulmonary hypertension (P = .89). Poor late survival was predicted by low indexed effective orifice area (< or =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 < or = .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.