Background: The effect of prosthesis-patient mismatch on long-term survival after mitral valve replacement (MVR) has received limited attention. This study was performed to determine the predictors of mortality after MVR and influence of prosthesis-patient mismatch on survival.
Methods: Contemporary mechanical prostheses and bioprostheses were implanted in 2,440 patients with MVR between 1982 and 2002. The mean age was 63.9 +/- 12.1 years and the mean follow-up was 6.1 +/- 4.6 years, a total of 14,797.7 years of follow-up. Prosthesis-patient mismatch was classified by effective orifice area index categories: normal, greater than 1.2 cm(2)/m(2) (345, 14.2%); mild-to-moderate, equal to or less than 1.2 to greater than 0.9 cm(2)/m(2) (1,696, 69.5%); and severe, equal to or less than 0.9 cm(2)/m(2) (399, 16.4%).
Results: The predictors of overall mortality were age, age categorization, New York Heart Association III-IV, concomitant coronary artery bypass, ventricular dysfunction, prosthesis type, body mass index, and pulmonary hypertension. All categories of effective orifice area indices (EOAIs) were not predictive of overall mortality, late mortality, or early mortality. The 15-year survival was not differentiated by EOAI categories; 32.0 +/- 4.4%, 32.9 +/- 2.1%, and 36.6 +/- 6.3%, respectively, for the three categories. Pulmonary hypertension influenced mortality by EOAI categories; normal versus mild-to-moderate (p = 0.0317) and normal versus severe (p = 0.0320). The EOAI was not an independent predictor of mortality in the consideration of patients with pulmonary hypertension but there is an interaction between pulmonary hypertension and mild-to-moderate (p = 0.023) and severe (p = 0.031) EOAI.
Conclusion: Prosthesis-patient mismatch is not a predictor of overall mortality to 15 years after MVR regardless of the category of effective orifice area index. The preoperative variable, pulmonary hypertension, influences overall mortality in the presence of mild-to-moderate and severe prosthesis-patient mismatch in the survival analysis.