Commentary: Another layer to the "PPM conundrum".

How do manufacturer estimates of valve performance match up to reality and stress testing? We are reviewing a manuscript by Porterie et al. in the Journal of Cardiac Surgery detailing a single-center, assessment of Avalus™ bioprosthetic valve hemodynamics during stress echocardiography. At maximal stress, they found that indexed effective orifice area had better alignment with manufacturer estimates than measurements at rest. In addition, they found a significant difference between EOA and flow rates at rest versus maximal exertion and quantified it as the "opening reserve." Patients without patient prosthetic mismatch had much higher opening reserves. This interesting study helps us to understand how estimates align with reality and draws attention to the concept of the opening reserve. Could differences in opening flow impact the durability or longevity of prosthetics?