Prevention of Moderate Prosthesis-Patient Mismatch: Individualization Versus Generalization

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Correspondence: Dr J. G. Dumesnil, Institut Universitaire de Cardiologie et de Pneumologie de Quebec / Quebec Heart and Lung Institute, Laval University, 2725 Chemin Sainte-Foy, Quebec, G1V-4G5, Quebec, Canada E-mail: jean.dumesnil@med.ulaval.ca In this issue of Revista espanola de CaRdiologia, Urso et al1 analyze the impact of moderate prosthesis-patient mismatch (PPM) on 30-day mortality following aortic valve replacement (AVR) in 272 patients aged 66 to 76 years (median age, 72 years). In the opinion of the authors, justification for the study is based on the fact that there is still some uncertainty as to whether moderate PPM independently influences survival and should thus be a consideration when operating on these patients given that, in this situation, the main conundrum faced by the surgeon is either to carry out an annular enlargement procedure, which may increase surgical risk, or to carry out the operation with the prosthesis as initially chosen and accept the consequences of moderate PPM. Having indeed found no difference between patients with and without moderate PPM, they imply in their conclusion that the importance of moderate PPM may have been overemphasized in the past and that it may not be an important consideration after all. Our spontaneous reaction after reading this paper is 2-fold. First, we are impressed by the fact that none of the patients in this series had severe PPM. This finding is confirmation that the prevalence of severe PPM has decreased substantially over the last decade due to: a) generalized recognition and awareness that, notwithstanding associated conditions, severe PPM is definitely associated with adverse outcomes and that it should thus be avoided in all patients undergoing AVR; b) widespread implementation of the preventive strategy utilized to calculate the projected indexed effective orifice area of the prosthesis to be implanted so that alternative strategies may be adopted if severe PPM is anticipated; and c) improved design and hemodynamic performance of newer generation prostheses. On the other hand, we are somewhat surprised that such findings and the conclusion are being reported by this particular group. Indeed, Urso et al1 have previously published 2 papers on the same topic2,3 and their conclusions and implications appear to be significantly different from the present ones. Hence, in a series of 163 patients over 75 years old, they reported that moderate PPM did not have a negative impact on mid-term mortality but was associated with a significant reduction of the quality of life2 and we agreed at the time that these findings could become a justification for avoiding moderate PPM in patients with a good functional class if this could be accomplished at an acceptable risk/ benefit ratio.4 As well, in another study based on an extensive review of the literature, they concluded that severe PPM was generally associated with poor outcomes and should ideally be avoided in all cases, whereas moderate PPM could be an independent risk factor of early and mid-term overall survival in the subgroup of patients with associated left ventricular (LV) dysfunction.3 From the latter 2 papers, one could logically have surmised that there are definite advantages to avoiding moderate PPM in certain circumstances and that the decision in this regard should be individualized depending on the patient’s underlying condition and the risk-benefit ratio of altering the originally planned operative strategy. Surprisingly, the present paper seems to backtrack from this more sophisticated approach and rather presents a generalization that can easily be interpreted as implying that moderate PPM is not an important consideration in the operative strategy of patients undergoing AVR and can thus almost be ignored in all cases.