Prediction of valve prosthesis-patient mismatch prior to aortic valve replacement: which is the best method?

Background: To predict the occurrence of valve prosthesis-patient mismatch ( VP-PM) after aortic valve replacement ( AVR), the surgeon needs to estimate the postoperative effective orifice area index ( EOAI). Aim: To compare different methods of predicting VP-PM. Methods: The effective orifice area ( EOA) of 383 patients who had undergone AVR between July 2000 and January 2005 with various aortic valve prostheses was obtained echocardiographically 6 months after the operation. We tested the efficacy of ( 1) EOAI calculated from the echo data obtained in our own laboratory, ( 2) indexed geometric orifice area, ( 3) EOAI estimated from charts provided by prosthesis manufacturers ( which are based either on in vitro or on echo data) and ( 4) EOAI estimated from reference echo data published in the literature to predict VP-PM. Results: Sensitivity and specificity to predict VP-PM were 53% and 83% ( method 1), 80% and 53% ( charts based on echo data, parts of method 3) and 71% and 67% ( method 4) using reference data derived from echocardiographic examinations. The sensitivity of method 2 and of charts based on in vitro data ( parts of method 3) to predict VP-PM was 0-17%. The incidence of severe VP-PM could be reduced from 8.7% to 0.8% after the introduction of the systematic estimation of the EOAI at the time of operation ( p = 0.003, method 1). Conclusions: The best method of predicting VP-PM is the use of mean ( SD) EOAs derived from echocardiographic examinations, whereas the use of in vitro data or the geometric orifice area is unreliable. After the surgeon's anticipation of VP-PM prior to AVR, the incidence of VP-PM could be reduced.