Effect of prosthesis-patient mismatch on survival after aortic valve replacement using mechanical prostheses in patients with aortic stenosis

Background  This study assessed the effects of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) using mechanical prostheses in patients with aortic stenosis. Methods  A total of 124 patients with aortic stenosis who underwent AVR with mechanical prostheses were followed (mean 9.1 ± 4.9 years). The patients were divided into two groups based on the effective orifice area index (EOAI): Group A did not have significant PPM, defined as an EOAI ≥ 0.85 cm²/m²; and the PPM group had significant PPM, defined as an EOAI < 0.85 cm²/m². Results  In all, 25 patients (20.2%) had PPM. The operative mortality was 6.1% in group A and 12.0% in the PPM group; the difference between the groups was not significant. Moreover, the difference in overall survival rates between group A and the PPM group was not statistically significant (15-year postoperative survival: group A 78.5% vs. PPM group 81.3%). Although there were four late deaths in the PPM group, only one was valve-related. PPM had no effect on late survival. Postoperatively, cardiac function and physical activity levels improved in both groups; the extent of improvement was not dependent on the presence or severity of PPM. Conclusion  Although PPM may affect operative mortality, the effect of PPM appears to decrease over time. PPM had no effect on late survival.