How reliable is an effective orifice area indexed chart?

Abstract

Background and aim of the study: Patient-prosthesis mismatch (PPM) occurs when a valvular prosthesis is too small relative to the patient's body surface area (BSA). The presence of PPM results in increased transprosthetic gradients and may portend a worse prognosis. It has been shown that reliable effective orifice area (EOA) data can be used to accurately predict PPM, thus preventing its occurrence. The study aim was to assess the predictive abilities of an effective orifice area indexed (EOAI) chart--the Perimount Magna EOAI chart--in the prevention of PPM.

Methods: A retrospective comparison of projected versus calculated EOA values and the predicted versus actual incidence of PPM was conducted. Forty patients with a Perimount Magna aortic bioprosthesis implanted between 1st January 2006 and 31st March 2009, were identified. The sensitivity, specificity, positive-predictive value (PPV) and negative predictive value (NPV) were each calculated using the Perimount Magna EOAI chart, to assess how well it could predict the incidence of postoperative PPM.

Results: The Perimount Magna EOAI chart had a sensitivity of 35% for predicting postoperative PPM, and an NPV of 53%. The projected EOA-values were almost invariably larger than those actually measured; this resulted in a higher proportion of patients than in whom PPM was predicted preoperatively. This EOAI chart proved to be very specific, with specificity of 100% and a PPV of 100%.

Conclusion: The Perimount Magna EOAI chart, based on mean EOA data from a small echocardiographic cohort, represents a poor method of predicting and preventing PPM. Rather, EOAI charts should be based on reliable EOA data that reproducibly predict the expected EOA for that prosthesis.