doi: 10.1161/CIRCULATIONAHA.105.576041
(Circulation. 2005;112:e333.)
© 2005 American Heart Association, Inc.
Correspondence |
Letter Regarding Article by Koch et al, "Impact of Prothesis–Patient Size on Functional Recovery After Aortic Valve Replacement"
Research Center of Laval Hospital/Quebec Heart Institute, Laval University, Sainte-Foy, Quebec, Canada
Hospital Poliambulanza, Brescia, Italy
We have read with interest the article by Koch et al.1 The conclusion is that "prothesis–patient size does not influence functional recovery after aortic valve replacement ...." As appropriately pointed out by the authors, this result is at odds with many previous studies showing that patient-prosthesis mismatch (PPM) has an impact on perioperative and postoperative outcomes and that the discrepancy could be related to the parameter chosen to characterize PPM. Hence, these authors use the internal geometric area (IGA), whereas many other studies2 have used the effective orifice area (EOA), and it thus becomes important to clearly understand the intrinsic differences between these two parameters.
The IGA is derived from the static measurement of the diameter of the prosthesis. It should be noted that the criteria used for this measurement are different for each type of prosthesis and that the indexed IGA has never been shown to have any relevance to postoperative hemodynamics. This observation is indeed corroborated by the results of the present study, whereby, compared with allografts, pericardial valves have very similar values for indexed IGA but approximately 2-fold values for peak and mean gradients (see Figure 2 and Table 1 of the article). In contrast, the indexed EOA is a hemodynamic parameter, which has consistently been shown to correlate with postoperative gradients.
Given these fundamental differences, we would therefore submit that the terminology used should be without ambiguity and in particular, that the term "indexed orifice area" should not be used without specifying whether it is indexed IGA or EOA, as was done in Figure 2. Also, given that the term PPM stems from a hemodynamic concept, its use should be reserved for data relating to hemodynamics (eg, indexed EOAs and gradients), whereas it would seem more appropriate to describe the results of the present study exclusively in terms of patient-prosthesis size, without using the term mismatch, thus avoiding much confusion. The use of proper terminology is important because, as further demonstrated by this study, patient-prosthesis size is seldom related to outcomes, whereas it is the opposite for PPM.2 Moreover, PPM can largely be avoided by using a preventive strategy at the time of operation.2
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 Top References References |
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1. Koch CG, Khandwala F, Estafanous FG, Loop FD, Blackstone EH. Impact of prothesis–patient size on functional recovery after aortic valve replacement. Circulation. 2005; 111: 3221–3229.
2. Blais C, Dumesnil JG, Baillot R, Simard S, Doyle D, Pibarot P. Impact of prothesis–patient mismatch on short-term mortality after aortic valve replacement. Circulation. 2003; 108: 983–988.
Department of Cardiothoracic Anesthesia (G-3), The Cleveland Clinic Foundation, Cleveland, Ohio
Department of Biostatistics, The Cleveland Clinic Foundation, Cleveland, Ohio
Division of Anesthesia, The Cleveland Clinic Foundation, Cleveland, Ohio
Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio
Over the years, Dr Pibarot and colleagues have contributed enormously to our understanding of prosthesis–patient mismatch. We agree that the term prosthesis–patient size should be reserved for expressing the continuous relation of prosthesis dimensions, however expressed, to body size, as proposed previously.1,2 We disagree that prosthesis–patient mismatch is fundamentally a hemodynamic concept; originally, it referred to a clinical syndrome.3 Semantics aside, readers need to understand our long-standing differences in perspective about the clinical importance of prosthesis size.
In our view, with so little evidence that prosthesis size makes a substantial impact on long-term mortality and quality of life, it is time to identify other factors that might be more important in improving outcomes after AVR.
Response
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1. Blackstone EH, Cosgrove DM, Jamieson WR, Birkmeyer NJ, Lemmer JH Jr, Miller DC, Butchart E, Rizzoli G, Yacoub M, Chai A. Prosthesis size and long-term survival after aortic valve replacement. J Thorac Cardiovasc Surg. 2003; 126: 783–796.
2. Blackstone EH, Gillinov AM, Cosgrove DM III. Reply to the editor: Prosthesis size and prosthesis–patient size are unrelated to prosthesis–patient mismatch. J Thorac Cardiovasc Surg. 2004; 127: 1852–1854.
3. Rahimtoola SH, Murphy E. Valve prosthesis-patient mismatch: a long-term sequela. Br Heart J. 1981; 45: 331–335.
4. Garg V, Muth AN, Ransom JF, Schluterman MK, Barnes R, King IN, Grossfeld P, Srivastava D. Mutations in NOTCH1 cause aortic valve disease. Nature. 2005; 437: 270–274.[CrossRef][Medline] [Order article via Infotrieve]
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