Prosthesis-patient mismatch affects survival after aortic valve replacement

Background-Surgeons traditionally avoid the use of "small" aortic prosthese s because of the potential for residual left ventricular outflow tract obst ruction and persistent transvalvular gradients. This study examines the rat io between prosthetic valve size and the body surface area (BSA) of patient s undergoing aortic valve replacement (AVR). We sought to determine the eff ect of potential "prosthesis-patient" mismatch on long-term survival. Methods and Results-Follow-up was conducted on 2981 patients who underwent AVR with stented bioprostheses between 1976 and 1996. To account for differ ences between manufacturers' labeled valve sizes, we calculated the ratio b etween the prosthetic valve effective orifice area (EOA) and the patient's BSA (recorded for 2154 patients). The lowest decile in this cohort had a ca lculated EOA/BSA of <0.75 cm(2)/m(2) (Small group, n=227) compared with the control group (n=1927), in whom the EOA/BSA ratio was >0.75 cm(2)/m(2). Op erative mortality was higher in the Small group (8% versus 5%, P=0.03), Act uarial survival at 12 years was 50+/-5% in the Small group compared with 49 +/-2% in the control group (P=0.27). However, freedom from valve-related mo rtality was significantly lower in the Small group (75+/-5% versus 84+/-2%, P=0.004). Cox regression analysis determined age and NYHA functional class to be the multivariate predictors of overall mortality, whereas advanced a ge and EOA/BSA <0.75 cm(2)/m(2) were found to be the predictors of valve-re lated mortality. Conclusions-Prosthesis-patient mismatch results in significantly higher ear ly and late mortality after bioprosthetic AVR. We recommend careful selecti on of stented bioprostheses to ensure an adequate ratio of EOA to BSA. An E OA/BSA ratio of >0.75 cm(2)/m(2) may avoid residual left ventricular outflo w tract obstruction and persistent transvalvular gradients. Careful prosthe sis-patient matching will improve both early and late survival after AVR.