Does patient-prosthesis mismatch have a negative impact on outcomes following mitral valve replacement?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether patient-prosthesis mismatch (PPM) has a negative impact on patients undergoing mitral valve replacement in terms of postoperative mortality, incidence of postoperative pulmonary hypertension (PH) and higher transmitral gradients. Altogether 103 papers were found using the reported search, 18 of which represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Overall, 8 studies with a total of 4812 patients reported that PPM has a significantly negative impact on long-term mortality, whereas 5 studies with a total of 1558 patients reported no effect on mortality. One study with a total of 2440 patients reported preoperative PH as the risk factor for increased mortality in the presence of moderate or severe PPM. Three studies evaluated the effect of PPM on postoperative PH and reported that PPM was associated with significantly increased postoperative PH. The majority of the studies reported that PPM was associated with higher peak or mean transmitral gradient and systolic pulmonary artery pressure. The results presented in these studies suggest that PPM in patients undergoing mitral valve replacement was associated with increased postoperative mean and peak transmitral gradient and higher postoperative systolic pulmonary artery pressure. PPM may be associated with increased long-term mortality. Severe PPM was directly associated with increased long-term mortality when compared with moderate or no PPM. Evidence suggests that PPM is associated with increased incidence of postoperative PH.