Abstract 17635: Can Published Reference Values Predict Patient-prosthesis Mismatch?

Abstract

Background: Patient-prosthesis mismatch (PPM) is still a frequently encountered problem after aortic valve surgery for aortic stenosis(AS). Advanced planning for prevention of PPM would be beneficial. We hypothesized that identification of severe PPM based on chosen surgical valve will predict development of severe PPM after surgery. Methods: Fifty one patients (74±13yrs) with severe aortic valve stenosis who underwent aortic valve surgery had postoperative echocardiogram (TTE) within 6 months. Severe PPM was defined as effective orifice area index (EOAI)<0.65 cm2/m2.We calculated predicted severe PPM using published references values of the prosthetic valve. We used mean value and the values one standard deviation above and below. We compared these values to the actual PPM based on postoperative TTE. Results: All patients had severe AS (MG50±7 mm Hg) and an LV EF of 56±15%. Forty four patients had tissue valves implanted and 7 had mechanical valves implanted. Mean time between postoperative TTE and surgery was 39± 60 days. When the mean reference values for the valve implanted was used, only 1 patient (2%) was predicted to have severe PPM. However, based on postoperative TTE, 6 patients (13%) had severe PPM. There was no correlation between EOAI based on postop TTE and mean published reference values (Figure).When the EOAI below one SD of the published reference value was chosen, the predicted incidence of severe PPM was 38%. When the EOAI above one SD was chosen for the reference value none of the patients were predicted to have PPM. Sensitivity and specificity to identify severe PPM was 17% and 100% for mean published reference value while it was 0% and 100% for +1 SD and 83% and 68% for -1 SD. Conclusions: 1) Use of mean published reference values markedly under estimate the true incidence of post-operative PPM and has unacceptably low sensitivity. 2) Predicted occurrence of PPM was widely variable (0% to 38%) based on the published reference values. Larger studies are needed.