Prosthesis-patient mismatch after mitral valve replacement stratified by referred and measured effective valve area

The aim of this study was to determine the impact of patient-prosthesis mismatch (PPM) after mitral valve replacement (MVR) on the late clinical outcome, evaluated from the referred value and measured mitral valve area in the echocardiograph.

The records of 212 patients who underwent MVR between 1995 and 2008 at Funabashi Municipal Medical Center, Japan were studied retrospectively. Exclusions were patients who had a repeat MVR or concomitant aortic valve surgery. Of 212 patients, 163 underwent the Doppler echocardiographic study more than 1 year after surgery. Primary endpoint was late survival, and secondary endpoint was major adverse cardiac event (MACE). The average follow-up period was 53.1 ± 100.8 months. The effective orifice area index (EOAI) was calculated using the referred effective orifice area (r-EOA) and measured effective orifice area (m-EOA). An EOAI smaller than 1.2 cm2/m2 defined PPM.

For r-EOAI, 125 patients (group P) had PPM and 87 patients (group N) did not. Between groups, there was a significant difference in the proportion of males (group P vs. N; 59% vs. 23%; P = 0.0001), postoperative NYHA class (1.02 ± 6.2 vs. 9.8 ± 1.6, P = 0.04), late mitral valve area (MVA) (2.50 ± 0.56 vs. 2.78 ± 0.60, P = 0.005), and peak transmitral pressure gradient (MPG) 11.9 ± 6.2 vs 9.8 ± 1.6, P = 0.04). However, there was no difference in late survival (P = 0.55) or incidence of a major cardiac adverse event (MACE) (P = 0.14). For m-EOAI, 17 patients (group P) had PPM and 146 patients (group N) did not. Between groups, there was a difference in the bioprosthetic valve (group P vs. N; 76% vs. 26%, P = 0.006) and mean MPG (5.2 ± 2.3 vs. 3.7 ± 1.8, P = 0.02). However, there was no difference in late survival (P = 0.99) and incidence of MACE (P = 0.86). The r- and m-EOAI were well correlated (correlation coefficient 0.46; 0.33-0.5)

The PPM after MVR was not related to the late survival or the incidence of MACE based on both r- and m-EOAI. The patient group of PPM defined by r-EOAI tended to be male and that defined by m-EOAI tended to be bioprosthetic.