Patient-prosthesis mismatch does not affect survival following aortic valve replacement

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Clinical Outcomes Research

Background:

• Patient-prosthesis mismatch (PPM) is a potential complication following aortic valve replacement (AVR).
• Previous studies suggest PPM may increase perioperative mortality and decrease long-term survival.
• The clinical significance of severe PPM following AVR requires further investigation.

Purpose of the Study:

• To analyze the effect of severe patient-prosthesis mismatch on survival after AVR.
• To evaluate the incidence of severe PPM in patients undergoing AVR in a specific clinical unit.
• To identify predictors of survival in patients following AVR.

Main Methods:

• Prospective data collection from 1481 patients undergoing AVR between 1997 and 2005.
• Evaluation of projected in vitro valve effective orifice area (EOA) and geometric prosthesis internal orifice area (GOA), indexed to body surface area.
• Definition of severe PPM as EOAi<0.6 and/or GOAi<1.1; long-term survival data obtained from national statistics.

Main Results:

• Severe PPM (EOAi<0.6 or GOAi<1.1) was identified in 4.7% to 8.6% of patients (combined 2.6%).
• No significant difference in in-hospital mortality (5.3% overall) between mismatch and reference groups.
• Five-year survival estimates were similar (83% PPM group vs. 81% reference group; p=0.47), with advanced age (>80) as the only predictor of reduced survival.

Conclusions:

• Severe patient-prosthesis mismatch occurs in a small percentage of AVR patients (4-10%).
• This degree of mismatch did not adversely affect in-hospital mortality.
• Mid-term survival following AVR was not significantly impacted by severe patient-prosthesis mismatch.