Impact of Prosthesis Size and Prosthesis-Patient Mismatch on Outcomes in Younger Female Patients Undergoing Aortic Valve Replacement

Abstract

The effects of patient-prosthesis mismatch (PPM) after surgical aortic valve replacement (SAVR) suggest worse outcomes with smaller valves. We assessed clinical outcomes of younger females undergoing SAVR, using small and large prostheses, and the incremental risk of PPM. Between January 2002 and June 2015, 451 younger (age ≤65 years) female patients underwent SAVR. Patients were stratified into small prostheses (SP) ≤21 mm (n = 256) and large prostheses (LP) ≥23 mm (n = 195) groups. PPM was classified as moderate if indexed effective orifice area (iEOA) 0.65-0.85 cm²/m², or severe if iEOA <0.65 cm²/m². Operative mortality was not statistically different between SP and LP groups (2.4% vs 0.5%; P = 0.146). Unadjusted 10-year survival was 82% (95% confidence interval 77-87%), and was similar in both groups (P = 0.210). When grouped by standard PPM thresholds, only severe PPM was associated with significantly decreased survival (P = 0.007). A significant survival decrease was detected in LP group with iEOA ≤0.75 cm²/m² (P < 0.001). Among SP patients, iEOA ≤0.65 cm²/m² was associated with increased mortality (P = 0.075). After adjusting for potential confounders, Cox proportional hazard model identified iEOAs of ≤0.65 cm²/m² (hazard ratio 1.85; P = 0.066) and ≤0.75 cm²/m² (hazard ratio 2.3; P ≤ 0.003) as predictors of decreased long-term survival, in SP and LP groups, respectively. Among younger females who underwent SAVR, postoperative complications and in-hospital outcomes were substantially similar between the SP and LP groups. However, patients who received LP were adversely affected at lesser degrees of PPM than those who received SP. While SP patients may tolerate until iEOA ≤0.65 cm²/m², our results suggest that moderate PPM of iEOA ≤0.75 for LP patients should be avoided.

Keywords: aortic valve replacement; gender; prosthesis mismatch.