Prosthesis-patient mismatch is not synonymous with elevated transvalvular pressure gradient

Dr Pibarot has received research grants from Edwards Lifesciences and Medtronic for echocardiography core laboratory services, for which he receives no direct industry compensation. He is supported by a Canada Research Chair and Foundation grant ( FDN-143225 ) from Canadian Institutes of Health Research , Ottawa, Ontario, Canada. The other author reported no conflicts of interest.The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. Dr Pibarot has received research grants from Edwards Lifesciences and Medtronic for echocardiography core laboratory services, for which he receives no direct industry compensation. He is supported by a Canada Research Chair and Foundation grant ( FDN-143225 ) from Canadian Institutes of Health Research , Ottawa, Ontario, Canada. The other author reported no conflicts of interest. The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. Vriesendorp and colleagues1Vriesendorp M.D. Deeb G.M. Reardon M.J. Kiaii B. Bapat V. Labrousse L. et al.Why the categorization of indexed effective orifice area is not justified for the classification of prosthesis–patient mismatch.J Thorac Cardiovasc Surg. November 12, 2020; ([Epub ahead of print])Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar recently evaluated the relationship between the effective orifice area indexed (EOAi) to body surface area and the postoperative transprosthetic mean gradient in patients undergoing surgical aortic valve replacement (AVR) using a stented bioprosthesis. The authors conclude that the current EOAi thresholds proposed in the American and European society guidelines and the Valve Academic Research Consortium-2 are not appropriate to define prosthesis–patient mismatch (PPM) because their ability to predict high residual transprosthetic gradients is weak. The study by Vriesendorp and colleagues1Vriesendorp M.D. Deeb G.M. Reardon M.J. Kiaii B. Bapat V. Labrousse L. et al.Why the categorization of indexed effective orifice area is not justified for the classification of prosthesis–patient mismatch.J Thorac Cardiovasc Surg. November 12, 2020; ([Epub ahead of print])Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar is based on the premise that the presence of PPM necessarily implies elevated transprosthetic pressure gradient. Indeed, in patients with normal left ventricular outflow, there is a strong and inverse curvilinear relationship between EOAi and transvalvular gradient. However, this relationship does not hold anymore if transvalvular flow is reduced, such as is the case in a large proportion (≤45%) of patients following AVR.2Pibarot P. Clavel M.A. Prosthesis–patient mismatch after transcatheter aortic valve replacement: it is neither rare nor benign.J Am Coll Cardiol. 2018; 72: 2712-2716Crossref PubMed Scopus (10) Google Scholar In the presence of low flow, the mean transprosthetic gradient may be pseudonormal despite the presence of a bona fide severe PPM. This phenomenon is analogous to low-flow, low-gradient native aortic stenosis, in which the transaortic gradient may be low despite the presence of true severe aortic stenosis. Hence, the mean transprosthetic gradient or peak transprosthetic velocity lack sensitivity to identify PPM, particularly in patients with low flow state (Figure 1). These parameters should thus not be used as a reference to confirm the presence or absence of PPM.3Généreux P. Piazza N. Alu M.C. Nazif T. Hahn R.T. Pibarot P. et al.Valve Academic Research Consortium 3: updated endpoint definitions for aortic valve clinical research.Eur Heart J. 2021; 42: 1825-1857Crossref PubMed Scopus (31) Google Scholar As opposed to the mean gradient or peak velocity, the EOAi measured by Doppler echocardiography may overestimate the incidence and severity of PPM in patients in a low-flow state. Indeed, as in low-flow, low-gradient native aortic stenosis, the EOA and thus the EOAi may be pseudosevere in presence of low flow and may thus overestimate the severity of aortic stenosis or of PPM. Indeed, in presence of low flow, the bioprosthetic valve leaflets may not open fully and the measured EOA may thus be small and lead to the erroneous conclusion that severe PPM is present, whereas in fact, this is pseudosevere PPM. To overcome this limitation, it is recommended to use the predicted EOAi instead of the measured EOAi to identify and quantify PPM.4Lancellotti P. Pibarot P. Chambers J. Edvardsen T. Delgado V. Dulgheru R. et al.Recommendations for the imaging assessment of prosthetic heart valves: a report from the European Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiography, the Interamerican Society of Echocardiography and the Brazilian Department of Cardiovascular Imaging.Eur Heart J Cardiovasc Imaging. 2016; 17: 589-590Crossref PubMed Scopus (231) Google Scholar The predicted EOAi is calculated from the normal reference value of EOA for the model and size of prosthetic valve being implanted in the patient divided by the body surface area. The predicted EOAi has been shown to be superior to the measured EOAi to identify true severe PPM (Figure 1) and predict hemodynamic and clinical outcomes following AVR.5Ternacle J. Guimaraes L. Vincent F. Cote N. Cote M. Lachance D. et al.Reclassification of prosthesis–patient mismatch after transcatheter aortic valve replacement using predicted vs. measured indexed effective orifice area.Eur Heart J Cardiovasc Imaging. 2021; 22: 11-20Crossref Scopus (5) Google Scholar To obtain accurate predicted EOAi, it is essential to use reliable sources for the normal reference values of EOAs,4Lancellotti P. Pibarot P. Chambers J. Edvardsen T. Delgado V. Dulgheru R. et al.Recommendations for the imaging assessment of prosthetic heart valves: a report from the European Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiography, the Interamerican Society of Echocardiography and the Brazilian Department of Cardiovascular Imaging.Eur Heart J Cardiovasc Imaging. 2016; 17: 589-590Crossref PubMed Scopus (231) Google Scholar which are not necessarily those provided by the prosthetic valve manufacturers. Furthermore, it is recommended to use lower threshold values of EOAi (<0.55 vs 0.65 cm2/m2 for severe PPM) in patients with obesity to avoid overindexation of EOA and thus overestimation of PPM in these patients (Figure 1).3Généreux P. Piazza N. Alu M.C. Nazif T. Hahn R.T. Pibarot P. et al.Valve Academic Research Consortium 3: updated endpoint definitions for aortic valve clinical research.Eur Heart J. 2021; 42: 1825-1857Crossref PubMed Scopus (31) Google Scholar To enhance the definition, prediction, and prevention of PPM following AVR, a task force led by International Organisation for Standardisation and Heart Valve Collaboratory has been launched to establish accurate and reliable normal reference values of EOAs for each given model and size of surgical or transcatheter bioprosthesis using a robust and standardized methodology. Why the categorization of indexed effective orifice area is not justified for the classification of prosthesis–patient mismatchThe Journal of Thoracic and Cardiovascular SurgeryPreviewAlthough the impact of prosthesis–patient mismatch (PPM) on survival has been widely studied, there has been little debate about whether the current definition of PPM truly reflects hemodynamic obstruction. This study aimed to validate the categorization of indexed effective orifice area (EOAi) for the classification of PPM. Full-Text PDF Open AccessReply: Relating the indexed effective orifice area and mean transprosthesis gradient to define patient–prosthesis mismatch: Are we sure a relationship exists?JTCVS OpenVol. 8PreviewWe thank Ternacle and Pibarot for their letter to the Editor and their interest in addressing patient–prosthesis mismatch (PPM) at the time of surgical aortic valve replacement (SAVR).1 The senior author, Dr Pibarot, should be recognized for his seminal contributions to the study of PPM. Much of our knowledge of PPM is related to Dr Pibarot's original paper that derived indexed effective orifice area (iEOA) thresholds associated with elevated gradients to define PPM. In the study by Pibarot and Dumesnil2 dating back to 2000, an exponential model was used to help determine sharp inflection points that were associated with elevated prosthetic valve mean gradients in 396 patients. Full-Text PDF Open AccessReply: The quest for zero gradientJTCVS OpenVol. 8PreviewSeveral decades after the implantation of the first aortic valve, the surgical community is still debating what residual gradient should be considered as acceptable, and how to measure the orifice prosthetic valve area in an unbiased manner. In other words, we are still debating how to define prosthesis–patient mismatch (PPM), and we are still wondering what effect PPM may have on patients' long-term outcomes. Full-Text PDF Open AccessReply: Prosthesis−patient mismatch: No consensus yetJTCVS OpenVol. 8PreviewThe definition and clinical impact of prosthesis−patient mismatch (PPM) has been a matter of intense debate and controversy.1,2 In response to the manuscript “Why the Categorization of Indexed Effective Orifice Area Is Not Justified for the Classification of Prosthesis−Patient Mismatch,” Ternacle and Pibarot3 proposed a new algorithm to better categorize patients having true severe PPM. They have used solid arguments to demonstrate that although mean transprosthetic gradients (mΔp) may underestimate the presence of true severe PPM, the opposite occurs when using measured effective orifice area indexes (mEOAi) for the same purpose. Full-Text PDF Open AccessReply from authors: Prosthesis–patient mismatch is not synonymous with elevated transvalvular pressure gradientJTCVS OpenVol. 8PreviewWe thank Ternacle and Pibarot for their letter in which they discuss that prosthesis–patient mismatch (PPM) is not the same as an elevated gradient across a prosthetic heart valve.1 In fact, the aim of our analysis was to validate previous results of their group published in the Journal of the American College of Cardiology, in which they propose the commonly used cut-off point for PPM.2 Their study shows that an indexed effective orifice (EOAi) area of 0.85 cm2/m2 corresponds with the point where mean aortic gradient accelerates, which directly implies that the presence of PPM corresponds with elevated transprosthetic pressure gradients. Full-Text PDF Open Access

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