Prosthesis–patient mismatch and clinical outcomes: The evidence continues to accumulate

Abstract

In this issue of the Journal, Ruel and associates1Ruel M. Al-Faleh H. Kulik A. Chan K.L. Mesana T.G. Burwash I.G. Prosthesis-patient mismatch after aortic valve replacement predominantly affects patients with pre-existing left ventricular dysfunction impact on survival, freedom from heart failure, and left ventricular mass regression.J Thorac Cardiovasc Surg. 2006; 131 (xxx–x)Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar report that aortic valve prosthesis–patient mismatch (PPM) predominantly affects patients with left ventricular (LV) dysfunction. As they point out, PPM remains a controversial issue. On the one hand, there is indeed an increasing body of evidence suggesting that PPM occurs frequently and has important clinical consequences.2Pibarot P. Honos G.N. Durand L.G. Dumesnil J.G. The effect of patient-prosthesis mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status.Can J Cardiol. 1996; 12: 379-387PubMed Google Scholar, 3Pibarot P. Dumesnil J.G. Lemieux M. Cartier P. Métras J. Durand L.G. Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity, and mortality after aortic valve replacement with a bioprosthetic heart valve.J Heart Valve Dis. 1998; 7: 211-218PubMed Google Scholar, 4Del Rizzo D.F. Abdoh A. Cartier P. Doty D.B. Westaby S. Factors affecting left ventricular mass regression after aortic valve replacement with stentless valves.Semin Thorac Cardiovasc Surg. 1999; 11: 114-120PubMed Google Scholar, 5Pibarot P. Dumesnil J.G. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention.J Am Coll Cardiol. 2000; 36: 1131-1141Abstract Full Text Full Text PDF PubMed Scopus (500) Google Scholar, 6Rao V. Jamieson W.R.E. Ivanov J. Armstrong S. David T.E. Prosthesis-patient mismatch affects survival following aortic valve replacement.Circulation. 2000; 102: III5-III9PubMed Google Scholar, 7Milano A.D. De Carlo M. Mecozzi G. D’Alfonso A. Scioti G. Nardi C. et al.Clinical outcome in patients with 19-mm and 21-mm St. Jude aortic prostheses comparison at long-term follow-up.Ann Thorac Surg. 2002; 73: 37-43Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar, 8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar, 9Mohty-Euhahidi D. Girard S.E. Malouf J.F. Connolly H.M. Balley K.R. Sarano M.E. et al.Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude mechanical prosthesis in the aortic position.Circulation. 2006; 113: 420-426Crossref PubMed Scopus (179) Google Scholar, 10Ruel M. Rubens F.D. Masters R.G. Pipe A.L. Bedard P. Hendry P.J. et al.Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves.J Thorac Cardiovas Surg. 2004; 127: 149-159Abstract Full Text Full Text PDF Scopus (132) Google Scholar, 11Tasca G. Brunelli F. Cirillo M. DallaTomba M. Mhagna Z. Troise G. et al.Impact of valve prosthesis-patient mismatch on left ventricular mass regression following aortic valve replacement.Ann Thorac Surg. 2005; 79: 505-510Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar, 12Botzenhardt F. Eichinger W.B. Bleiziffer S. Guenzinger R. Wagner I.M. Bauernschmitt R. et al.Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus.J Am Coll Cardiol. 2005; 45: 2054-2060Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 13Tasca G. Brunelli F. Cirillo M. Dalla Tomba M. Mhagna Z. Troise G. et al.Impact of the improvement of valve area achieved with aortic valve replacement on the regression of left ventricular hypertrophy in patients with pure aortic stenosis.Ann Thorac Surg. 2005; 79: 1291-1296Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar To the opposite, some authors have argued that PPM is a rare phenomenon without relevant clinical implications.14Medalion B. Blackstone E.H. Lytle B.W. White J. Arnold J.H. Cosgrove D.M. Aortic valve replacement is valve size important?.J Thorac Cardiovasc Surg. 2000; 119: 963-974Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar, 15Hanayama N. Christakis G.T. Mallidi H.R. Joyner C.D. Fremes S.E. Morgan C.D. et al.Patient prosthesis mismatch is rare after aortic valve replacement valve size may be irrelevant.Ann Thorac Surg. 2002; 73: 1822-1829Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 16Blackstone E.H. Cosgrove D.M. Jamieson W.R.E. Birkmeyer N.J. Lemmer Jr, J.H. Miller D.C. et al.Prosthesis size and long-term survival after aortic valve replacement.J Thorac Cardiovasc Surg. 2003; 126: 783-793Abstract Full Text Full Text PDF PubMed Scopus (204) Google Scholar, 17Knez I. Rienmüller R. Maier R. Rehak P. Schröttner B. Mächler H. et al.Left ventricular architecture after valve replacement due to critical aortic stenosis an approach to dis-/qualify the myth of valve prosthesis-patient mismatch?.Eur J Cardiothorac Surg. 2001; 19: 797-805Crossref PubMed Scopus (25) Google Scholar, 18Freed D.H. Tam J.W. Moon M.C. Harding G.E. Ahmad E. Pascoe E.A. Nineteen-millimeter prosthetic aortic valves allow normalization of left ventricular mass in elderly women.Ann Thorac Surg. 2002; 74: 2022-2025Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar, 19Koch C.G. Khandwala F. Estafanous F.G. Loop F.D. Blackstone E.H. Impact of prosthesis-patient size on functional recovery after aortic valve replacement.Circulation. 2005; 111: 3221-3229Crossref PubMed Scopus (83) Google Scholar The article from Ruel and colleagues1Ruel M. Al-Faleh H. Kulik A. Chan K.L. Mesana T.G. Burwash I.G. Prosthesis-patient mismatch after aortic valve replacement predominantly affects patients with pre-existing left ventricular dysfunction impact on survival, freedom from heart failure, and left ventricular mass regression.J Thorac Cardiovasc Surg. 2006; 131 (xxx–x)Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar brings new evidence from two standpoints: (1) It further documents the impact of PPM on long-term clinical outcomes such as survival, freedom from heart failure, and LV mass regression, whereas there has been a paucity of data in this regard and most studies have been limited to the short or medium term; (2) it adds a new dimension to this type of study in that it examines whether PPM and preoperative LV function interact with regard to their impact on these outcomes.See related article on page 1036. See related article on page 1036. Given the controversy that has surrounded PPM and to put the findings of Ruel and coworkers into proper perspective, it is important to review certain essential elements regarding this concept and its identification. Indeed, the term PPM was first coined in 1978 by Rahimtoola,20Rahimtoola S.H. The problem of valve prosthesis-patient mismatch.Circulation. 1978; 58: 20-24Crossref PubMed Scopus (692) Google Scholar who defined it as follows: “Mismatch can be considered to be present when the effective prosthetic valve area, after insertion into the patient, is less than that of a normal human valve.” In his original publication, the author insisted that the main consequence of PPM would be to produce higher postoperative gradients resulting in an increased hemodynamic burden for the ventricle, and he actually provided a graph summarizing his vision of the relation between the effective orifice area (EOA) of the prosthesis and postoperative gradients. However, the graph showed no normalization for body size and, as it stood, it could be interpreted as the conceptual relation that would exist between EOA and gradients in a person with average body size. Importantly, it must be emphasized that higher postoperative gradients and increased LV workload are inherent to the concept of PPM. Hence, an alternate definition for PPM could well be: “PPM occurs when the EOA of the prosthesis is too small in relation to the patient’s body size, resulting in abnormally high postoperative gradients.” The parameter first proposed to identify PPM has been the indexed EOA, which is the EOA of the prosthesis divided by the patient’s body surface area.21Dumesnil J.G. Honos G.N. Lemieux M. Beauchemin J. Validation and applications of indexed aortic prosthetic valve areas calculated by Doppler echocardiography.J Am Coll Cardiol. 1990; 16: 637-643Abstract Full Text PDF PubMed Scopus (221) Google Scholar, 22Dumesnil J.G. Yoganathan A.P. Valve prosthesis hemodynamics and the problem of high transprosthetic pressure gradients.Eur J Cardiothorac Surg. 1992; 6: S34-S38Crossref PubMed Google Scholar It should be emphasized that the EOA is a physiologic parameter derived from hydraulic principles and it corresponds to the area occupied by flow as it exits the valve. Clinically, it is calculated from either the continuity equation when using echocardiography or the Gorlin formula during cardiac catheterization. Unfortunately, it cannot be predicted from the size of the prosthesis or its geometric area because the criteria used to calculate the geometric area vary from one type of prosthesis to the other; in addition, the ratio between the EOA and the geometric area also varies widely from one type and/or size of prosthesis to another.8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar, 14Medalion B. Blackstone E.H. Lytle B.W. White J. Arnold J.H. Cosgrove D.M. Aortic valve replacement is valve size important?.J Thorac Cardiovasc Surg. 2000; 119: 963-974Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar, 23Muneretto C. Bisleri G. Negri A. Manfredi J. The concept of patient-prosthesis mismatch.J Heart Valve Dis. 2004; 13: S59-S62PubMed Google Scholar The rationale behind the normalization of the EOA for body surface area is to account for cardiac output requirements since transvalvular pressure gradients are essentially determined by the EOA and transvalvular flow, which in turn are largely determined by body size. Reference values for EOA data exist for each type and size of prosthesis,5Pibarot P. Dumesnil J.G. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention.J Am Coll Cardiol. 2000; 36: 1131-1141Abstract Full Text Full Text PDF PubMed Scopus (500) Google Scholar, 8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar and they should ideally be derived from in vivo rather than in vitro values since the latter are often more optimistic than the former and are not representative of the real-life situation. To this effect, it should be emphasized that, as was done in this study, the indexed EOA calculated from such reference values or from postoperative echocardiograms remains the only parameter that has been successfully validated to predict postoperative outcomes,2Pibarot P. Honos G.N. Durand L.G. Dumesnil J.G. The effect of patient-prosthesis mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status.Can J Cardiol. 1996; 12: 379-387PubMed Google Scholar, 3Pibarot P. Dumesnil J.G. Lemieux M. Cartier P. Métras J. Durand L.G. Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity, and mortality after aortic valve replacement with a bioprosthetic heart valve.J Heart Valve Dis. 1998; 7: 211-218PubMed Google Scholar, 4Del Rizzo D.F. Abdoh A. Cartier P. Doty D.B. Westaby S. Factors affecting left ventricular mass regression after aortic valve replacement with stentless valves.Semin Thorac Cardiovasc Surg. 1999; 11: 114-120PubMed Google Scholar, 5Pibarot P. Dumesnil J.G. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention.J Am Coll Cardiol. 2000; 36: 1131-1141Abstract Full Text Full Text PDF PubMed Scopus (500) Google Scholar, 6Rao V. Jamieson W.R.E. Ivanov J. Armstrong S. David T.E. Prosthesis-patient mismatch affects survival following aortic valve replacement.Circulation. 2000; 102: III5-III9PubMed Google Scholar, 7Milano A.D. De Carlo M. Mecozzi G. D’Alfonso A. Scioti G. Nardi C. et al.Clinical outcome in patients with 19-mm and 21-mm St. Jude aortic prostheses comparison at long-term follow-up.Ann Thorac Surg. 2002; 73: 37-43Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar, 8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar, 9Mohty-Euhahidi D. Girard S.E. Malouf J.F. Connolly H.M. Balley K.R. Sarano M.E. et al.Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude mechanical prosthesis in the aortic position.Circulation. 2006; 113: 420-426Crossref PubMed Scopus (179) Google Scholar, 10Ruel M. Rubens F.D. Masters R.G. Pipe A.L. Bedard P. Hendry P.J. et al.Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves.J Thorac Cardiovas Surg. 2004; 127: 149-159Abstract Full Text Full Text PDF Scopus (132) Google Scholar, 11Tasca G. Brunelli F. Cirillo M. DallaTomba M. Mhagna Z. Troise G. et al.Impact of valve prosthesis-patient mismatch on left ventricular mass regression following aortic valve replacement.Ann Thorac Surg. 2005; 79: 505-510Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar, 12Botzenhardt F. Eichinger W.B. Bleiziffer S. Guenzinger R. Wagner I.M. Bauernschmitt R. et al.Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus.J Am Coll Cardiol. 2005; 45: 2054-2060Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 13Tasca G. Brunelli F. Cirillo M. Dalla Tomba M. Mhagna Z. Troise G. et al.Impact of the improvement of valve area achieved with aortic valve replacement on the regression of left ventricular hypertrophy in patients with pure aortic stenosis.Ann Thorac Surg. 2005; 79: 1291-1296Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar as well as to prospectively prevent PPM24Castro L.J. Arcidi J.M.J. Fisher A.L. Gaudiani V.A. Routine enlargement of the small aortic root a preventive strategy to minimize mismatch.Ann Thorac Surg. 2002; 74: 31-36Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar and avoid high postoperative gradients. However, as is the case for many physiologic parameters, the EOA has some inherent variability that is mainly related to the techniques used for its measurement, as well as to a certain flow dependency. For this reason, some authors have alternatively attempted to characterize PPM in terms of the indexed internal geometric area (IGA) rather than the indexed EOA.14Medalion B. Blackstone E.H. Lytle B.W. White J. Arnold J.H. Cosgrove D.M. Aortic valve replacement is valve size important?.J Thorac Cardiovasc Surg. 2000; 119: 963-974Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar, 15Hanayama N. Christakis G.T. Mallidi H.R. Joyner C.D. Fremes S.E. Morgan C.D. et al.Patient prosthesis mismatch is rare after aortic valve replacement valve size may be irrelevant.Ann Thorac Surg. 2002; 73: 1822-1829Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 16Blackstone E.H. Cosgrove D.M. Jamieson W.R.E. Birkmeyer N.J. Lemmer Jr, J.H. Miller D.C. et al.Prosthesis size and long-term survival after aortic valve replacement.J Thorac Cardiovasc Surg. 2003; 126: 783-793Abstract Full Text Full Text PDF PubMed Scopus (204) Google Scholar In contrast to the EOA, the IGA is an anatomic parameter calculated from the static measurement of the internal diameter of the prosthesis. In this sense, it is very reproducible and exhibits little variability. However, it has consistently been shown to be unrelated to either postoperative gradients25Pibarot P. Dumesnil J.G. Cartier P.C. Métras J. Lemieux M. Patient-prosthesis mismatch can be predicted at the time of operation.Ann Thorac Surg. 2001; 71: S265-S268Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar or clinical outcomes.14Medalion B. Blackstone E.H. Lytle B.W. White J. Arnold J.H. Cosgrove D.M. Aortic valve replacement is valve size important?.J Thorac Cardiovasc Surg. 2000; 119: 963-974Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar, 15Hanayama N. Christakis G.T. Mallidi H.R. Joyner C.D. Fremes S.E. Morgan C.D. et al.Patient prosthesis mismatch is rare after aortic valve replacement valve size may be irrelevant.Ann Thorac Surg. 2002; 73: 1822-1829Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 16Blackstone E.H. Cosgrove D.M. Jamieson W.R.E. Birkmeyer N.J. Lemmer Jr, J.H. Miller D.C. et al.Prosthesis size and long-term survival after aortic valve replacement.J Thorac Cardiovasc Surg. 2003; 126: 783-793Abstract Full Text Full Text PDF PubMed Scopus (204) Google Scholar, 17Knez I. Rienmüller R. Maier R. Rehak P. Schröttner B. Mächler H. et al.Left ventricular architecture after valve replacement due to critical aortic stenosis an approach to dis-/qualify the myth of valve prosthesis-patient mismatch?.Eur J Cardiothorac Surg. 2001; 19: 797-805Crossref PubMed Scopus (25) Google Scholar, 18Freed D.H. Tam J.W. Moon M.C. Harding G.E. Ahmad E. Pascoe E.A. Nineteen-millimeter prosthetic aortic valves allow normalization of left ventricular mass in elderly women.Ann Thorac Surg. 2002; 74: 2022-2025Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar, 19Koch C.G. Khandwala F. Estafanous F.G. Loop F.D. Blackstone E.H. Impact of prosthesis-patient size on functional recovery after aortic valve replacement.Circulation. 2005; 111: 3221-3229Crossref PubMed Scopus (83) Google Scholar This point is well illustrated by the recent data of Koch and associates,19Koch C.G. Khandwala F. Estafanous F.G. Loop F.D. Blackstone E.H. Impact of prosthesis-patient size on functional recovery after aortic valve replacement.Circulation. 2005; 111: 3221-3229Crossref PubMed Scopus (83) Google Scholar whereby these authors reported identical values for indexed IGA in patients with pericardial valves and patients with allografts whereas peak and mean gradients were twice as high in the former as in the latter. Not surprisingly, the same article found no relation between the indexed IGA and the clinical outcome of functional recovery after surgery. As appropriately pointed out by the authors, one of the likely explanations for the discrepancy between their results and other studies showing a relation between PPM and clinical outcomes is the difference in choice of parameters to identify PPM. Hence, it becomes evident from a practical standpoint that, notwithstanding its limitations, the indexed EOA is the only parameter with proven validity to characterize PPM, prevent its occurrence, and predict postoperative outcomes. For this reason and to avoid further confusion, we would thus propose that the term PPM be used only with regard to data collected by use of the indexed EOA, whereas data collected by use of the indexed IGA should be more appropriately termed prosthesis–patient size. These considerations also further emphasize that it is not the size or the geometric dimensions of a prosthesis that are clinically relevant, but rather the match between its anticipated hemodynamic performance and the size of the patient. When the right parameter is used for its identification, PPM is also found be to a relatively frequent phenomenon5Pibarot P. Dumesnil J.G. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention.J Am Coll Cardiol. 2000; 36: 1131-1141Abstract Full Text Full Text PDF PubMed Scopus (500) Google Scholar, 8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar, 12Botzenhardt F. Eichinger W.B. Bleiziffer S. Guenzinger R. Wagner I.M. Bauernschmitt R. et al.Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus.J Am Coll Cardiol. 2005; 45: 2054-2060Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar akin to the 40% prevalence (325/805 patients) observed in the present study. To analyze how the relation between PPM and clinical outcomes might be affected by LV function is conceptually attractive since an increased hemodynamic burden should theoretically be less well tolerated by a poorly functioning ventricle than by a normal ventricle.26Connolly H.M. Oh J.K. Schaff H.V. Roger V.L. Osborn S.L. Hodge D.O. et al.Severe aortic stenosis with low transvalvular gradient and severe left ventricular dysfunction result of aortic valve replacement in 52 patients.Circulation. 2000; 101: 1940-1946Crossref PubMed Scopus (306) Google Scholar, 27Briand M. Dumesnil J.G. Kadem L. Tongue A.G. Rieu R. Garcia D. et al.Reduced systemic arterial compliance impacts significantly on LV afterload and function in aortic stenosis implications for diagnosis and treatment.J Am Coll Cardiol. 2005; 46: 291-298Abstract Full Text Full Text PDF PubMed Scopus (385) Google Scholar In this sense, the present results are extremely valuable in that they indirectly corroborate the data of Blais and colleagues,8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar showing a strong interaction between PPM and depressed LV function with regard to early mortality after AVR, and are the first to show that such an interaction also exists in relation to late mortality, heart failure, and LV mass regression. An important limitation of the study, however, is that characterization of LV function was based only on a visual estimate of the ejection fraction by one or more of four blinded observers. Given that LV function is a major and pivotal variable of the study, it is indeed unfortunate that the authors did not provide some measure of intraobserver or interobserver variability and/or did not corroborate their results by the use of a more objective method of quantifying the ejection fraction. In this context, it becomes difficult to ascertain what might have been the margin of error and how many patients might have been misclassified. This limitation also has to be taken into consideration when analyzing the clinical implications of the study. The threshold values of indexed EOA used to identify and classify PPM have also been a matter of discussion.10Ruel M. Rubens F.D. Masters R.G. Pipe A.L. Bedard P. Hendry P.J. et al.Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves.J Thorac Cardiovas Surg. 2004; 127: 149-159Abstract Full Text Full Text PDF Scopus (132) Google Scholar In the present study, the authors have elected to dichotomize their patients between those having an indexed EOA below or above 0.85 cm2/m2, whereas other studies have used threshold values ranging from 0.75 to 0.90 cm2/m2 to dichotomize patients. An alternate approach has also been to consider PPM as a continuum rather than a dichotomy and, as is routinely done for native aortic valve disease, to classify patients according to the degree of severity.7Milano A.D. De Carlo M. Mecozzi G. D’Alfonso A. Scioti G. Nardi C. et al.Clinical outcome in patients with 19-mm and 21-mm St. Jude aortic prostheses comparison at long-term follow-up.Ann Thorac Surg. 2002; 73: 37-43Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar, 8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar, 9Mohty-Euhahidi D. Girard S.E. Malouf J.F. Connolly H.M. Balley K.R. Sarano M.E. et al.Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude mechanical prosthesis in the aortic position.Circulation. 2006; 113: 420-426Crossref PubMed Scopus (179) Google Scholar, 12Botzenhardt F. Eichinger W.B. Bleiziffer S. Guenzinger R. Wagner I.M. Bauernschmitt R. et al.Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus.J Am Coll Cardiol. 2005; 45: 2054-2060Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar Indeed, when the latter approach is used, a strong relation can be found between the degree of severity of PPM and the prevalence of negative outcomes. For unknown reasons, the present study tested different thresholds of severity only in the case of LV mass and did indeed find significant differences. In the study of Blais and colleagues,8Blais C. Dumesnil J.G. Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar the impact of PPM was found to increase exponentially in relation to the degree of severity to the extent that even patients with normal LV function were found to have a significant increase in early mortality when faced with severe PPM. Hence, one cannot exclude that a similar result might not have been observed in the present study had a similar type of analysis been performed. The appropriateness of classifying PPM according to the degree of severity is also corroborated by other studies7Milano A.D. De Carlo M. Mecozzi G. D’Alfonso A. Scioti G. Nardi C. et al.Clinical outcome in patients with 19-mm and 21-mm St. Jude aortic prostheses comparison at long-term follow-up.Ann Thorac Surg. 2002; 73: 37-43Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar, 9Mohty-Euhahidi D. Girard S.E. Malouf J.F. Connolly H.M. Balley K.R. Sarano M.E. et al.Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude mechanical prosthesis in the aortic position.Circulation. 2006; 113: 420-426Crossref PubMed Scopus (179) Google Scholar, 12Botzenhardt F. Eichinger W.B. Bleiziffer S. Guenzinger R. Wagner I.M. Bauernschmitt R. et al.Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus.J Am Coll Cardiol. 2005; 45: 2054-2060Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar and is logical in the sense that, as for native aortic valve disease, the impact of PPM should be viewed in relative terms, that is, in terms of the degree of imbalance between LV afterload and the status of LV function.27Briand M. Dumesnil J.G. Kadem L. Tongue A.G. Rieu R. Garcia D. et al.Reduced systemic arterial compliance impacts significantly on LV afterload and function in aortic stenosis implications for diagnosis and treatment.J Am Coll Cardiol. 2005; 46: 291-298Abstract Full Text Full Text PDF PubMed Scopus (385) Google Scholar The clinical implications of this study are important in that they clearly demonstrate that PPM has a significant impact on important clinical outcomes such as late survival, freedom from heart failure, and LV mass regression and that this impact is highly modulated by the functional status of the LV before surgery. The temptation to conclude from these findings that PPM is an important consideration only in patients with reduced LV function and can almost be dismissed as irrelevant in patients with normal LV function should, however, be avoided. Indeed, because PPM was analyzed as a dichotomy rather than a continuum, it cannot be excluded that severe PPM also had an impact in patients with normal LV function. Moreover, on examination of Figures 1 and 2 from Ruel’s study,1Ruel M. Al-Faleh H. Kulik A. Chan K.L. Mesana T.G. Burwash I.G. Prosthesis-patient mismatch after aortic valve replacement predominantly affects patients with pre-existing left ventricular dysfunction impact on survival, freedom from heart failure, and left ventricular mass regression.J Thorac Cardiovasc Surg. 2006; 131 (xxx–x)Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar it is striking to see that patients with PPM and normal LV function tended to have poorer outcomes than those with no PPM and normal LV function, as well as those with no PPM and impaired LV function. Hence, the impact of PPM on clinical outcomes might well be at least as important as that of LV function. The fact that this did not come out in multivariate analysis might be due to the influence of other confounding variables. The issue is also further confounded by the potential variability in the estimate of the ejection fraction and the fact that patients with borderline values might have been misclassified. From a practical standpoint, to consider PPM irrelevant in a patient with normal LV function could be hazardous given that the eventual occurrence of severe PPM or misclassification of LV function cannot be excluded in the individual patient. In this context, it should be emphasized that the projected indexed EOA of the prosthesis to be inserted can be calculated before surgery and that, in the case of an anticipated PPM, alternate procedures such as aortic root enlargement24Castro L.J. Arcidi J.M.J. Fisher A.L. Gaudiani V.A. Routine enlargement of the small aortic root a preventive strategy to minimize mismatch.Ann Thorac Surg. 2002; 74: 31-36Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar or insertion of a better performing valve substitute (eg, supra-annular bioprostheses,28Botzenhardt F. Eichinger W.B. Guenzinger R. Bleiziffer S. Wagner I. Bauernschmitt R. et al.Hemodynamic performance and incidence of patient-prosthesis mismatch of the complete supraannular Perimount Magna bioprosthesis in the aortic position.Thorac Cardiovasc Surg. 2005; 53: 226-230Crossref PubMed Scopus (52) Google Scholar stentless valves,29Dumesnil J.G. LeBlanc M.H. Cartier P. Métras J. Desaulniers D. Doyle D. et al.Distinctive hemodynamic features of the Freestyle aortic bioprothesis as compared with stented bioprosthesis.Ann Thorac Surg. 1998; 66: S130-S133Abstract Full Text Full Text PDF PubMed Scopus (71) Google Scholar newer generation mechanical valves,30Bach D.S. Sakwa M.P. Goldbach M. Petracek M.R. 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Baillot R. Simard S. Doyle D. Pibarot P. Impact of prosthesis-patient mismatch on short-term mortality after aortic valve replacement.Circulation. 2003; 108: 983-988Crossref PubMed Scopus (460) Google Scholar Castro and coworkers24Castro L.J. Arcidi J.M.J. Fisher A.L. Gaudiani V.A. Routine enlargement of the small aortic root a preventive strategy to minimize mismatch.Ann Thorac Surg. 2002; 74: 31-36Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar have indeed demonstrated that such a strategy can be used successfully to prevent PPM, and most manufacturers now provide user-friendly charts allowing easy calculation of the projected indexed EOA within the operating room. In any given case, this information can easily be incorporated within the clinical decision-making process and used in view of the other pertinent clinical factors such as age, level of physical activity, status of LV function, and concomitant procedures. For instance, if one projects moderate PPM in an elderly patient with reduced physical activity and normal LV function, it might be estimated that the benefits of doing an alternate procedure to avoid PPM are outweighed by the inherent risks or disadvantages of doing such a procedure. On the other hand, the reverse could be true if severe PPM was projected in the same patient and/or if there was evidence of impaired LV function. In this context, the present results are further confirmation that the projected indexed EOA should routinely be calculated before aortic valve replacement and become an integral part of the clinical decision-making process. Finally, the observation that PPM has a significant impact on LV mass regression only in patients with impaired LV function is new and intriguing. It will require further validation and documentation with regard to physiopathology and potential clinical implications. Prosthesis–patient mismatch after aortic valve replacement predominantly affects patients with preexisting left ventricular dysfunction: Effect on survival, freedom from heart failure, and left ventricular mass regressionThe Journal of Thoracic and Cardiovascular SurgeryVol. 131Issue 5PreviewThe effect of prosthesis–patient mismatch on clinical outcome and left ventricular mass regression after aortic valve replacement remains controversial. Data on whether the clinical effect of prosthesis–patient mismatch depends on left ventricular function at the time of aortic valve replacement are lacking. This study examined the long-term clinical and echocardiographic effects of prosthesis–patient mismatch in patients with and without left ventricular systolic dysfunction at the time of aortic valve replacement. Full-Text PDF