Multivariate analysis of factors influencing the occurrence of patient prosthesis mismatch after aortic valve replacement

Objective: Since the introduction of the term prosthesis patient mismatch (PPM) in aortic valve surgery, cardiac surgeons as well as valve manufacturers developed several strategies to optimize the effective orifice area index (EOAI) that can be achieved for the individual patient by modifying surgical techniques and prosthetic valve design. Independent predictors of the occurrence of PPM were defined in 471 patients by multivariate analysis.

Methods: Multivariate logistic regression analysis was performed to obtain independent parameters that influence the risk for developing PPM after aortic valve replacement. Prospective echocardiographic evaluations were performed for all patients six months postoperatively by one experienced investigator.

Results: Patient age, gender and ejection fraction as well as the use of a stentless valve did not have a significant impact on the incidence of PPM. In contrast small aortic annulus diameter (OR: 0.7 per mm annulus diameter), position of the prosthesis (complete supraannular vs. intra-supra OR: 1.9), and type of the prosthesis (mechanical vs. pericardial OR: 4.4, mechanical vs. porcine OR: 9.6) could be identified as independent risk factors for PPM.

Conclusion: In patients with small aortic annuli who are at risk for developing PPM, the use of an optimized prosthesis e.g. a complete supraannular pericardial stented valve can be an easy applicable and effective alternative to surgically demanding techniques such as root enlargement. The use of stentless valves did not significantly reduce the risk of PPM. The overall lowest risk for PPM was identified for patients receiving a complete supraannular mechanical prostheses.