Abstract
Background Prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) may affect
survival but data are conflicting. It is assessed by relating effective orifice area
(EOA) to body surface area (EOAi). EOA is patient-specific as the result of flow-velocity
times area at the individual patient's outflow tract levels (LVOTA) divided by trans-prosthetic flow velocity. However, some studies use projected EOAs
(i.e., valve size associated EOAs from other patient populations) to assess how PPM
affects outcome.
Methods We analyzed 76 studies addressing hemodynamic outcome and/or mortality after bioprosthetic
AVR.
Results In 48 studies, projected or measured EOA for calculation of EOAi and PPM assessment
was used (of which 25 demonstrated an effect on survival). We identified 28 additional
studies providing measured EOA values and the corresponding Bernoulli's pressure gradients
after AVR. Despite EOA being a patient-specific parameter, 77% of studies assessing
a PPM impact on survival used projected EOAs. The 28 studies are providing measured
EOA values and the corresponding Bernoulli's pressure gradients in patients after
AVR showed a highly significant, linear relationship between EOA and Bernoulli's gradient.
Considering this relationship, it is surprising that relating EOA to body surface
area (BSA) (EOAi) is standard but relating pressure gradients to BSA is not.
Conclusion We conclude that the majority of studies assessing PPM have used false assumptions
because EOA is a patient-specific parameter and cannot be transferred to other patients.
In addition, the use of EOAi to assess PPM may not be appropriate and could explain
the inconsistent relation between PPM and survival in previous studies.
Keywords
aortic valve replacement - cardiac surgery - hemodynamic evaluation - echocardiography
- flow velocity - pressure gradient
