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(Circulation. 2006;114:e628.)
© 2006 American Heart Association, Inc.

Correspondence

Response to Letter Regarding Article, "Long-Term Outcomes After Valve Replacement for Low-Gradient Aortic Stenosis: Impact of Prosthesis-Patient Mismatch"

Alexander Kulik, MD; Varun Kapila, MD; Thierry G. Mesana, MD, PhD; Marc Ruel, MD, MPH

Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Canada

Ian G. Burwash, MD

Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Canada

An extract of the first 250 words of the full text is provided, because this article has no abstract.

We thank Bleiziffer and colleagues for their interest and insightful comments regarding our article¹ describing long-term outcomes after valve replacement for patients with low-gradient aortic stenosis. In our analyses, prosthesis-patient mismatch (PPM) was characterized as an indexed effective orifice area (EOA) of 0.85 cm²/m² because this definition constitutes the most generally accepted criterion for PPM.² As Bleiziffer et al note in their letter, the use of geometric internal orifice area as a measure of prosthesis size is limited and does not effectively predict hemodynamic or clinical outcomes. We did not use geometric orifice area in our analyses because geometric orifice area does not account for many valve characteristics that contribute to the EOA, such as prosthesis height, profile, opening angle, and leaflet inertia.

We agree with Bleiziffer and colleagues that the EOA derived by Doppler echo continuity equation from individual patients after implantation of the prosthesis may have better quantified the degree of PPM in our study of low-gradient aortic stenosis patients. This methodology has several important limitations, however, related to the difficulties caused by prosthetic valve reverberations in accurately measuring left ventricular outflow diameter after surgery. Moreover, the presence of large localized transprosthetic gradients or nonuniform transprosthetic spatial velocity profiles frequently result in large discrepancies between Doppler echo and actual EOA measurements.^3,4 Therefore, we used fixed values of in vivo EOAs (also known as projected EOAs) for each prosthesis type and size from literature sources of patients with normally functioning prostheses.² Projected EOA values can be attributed to . . . [Full Text of this Article]