Defining patient-prosthesis mismatch and its effect on survival in patients with impaired ejection fraction.

Background: How best to define patient-prosthesis mismatch (PPM) continues to be debated. Over time, the indexed effective orifice area has become the most widely used method. However, the clinical relevance of PPM remains controversial.

Methods: The indexed geometric orifice area and indexed effective orifice area were calculated for 143 patients having undergone aortic valve replacement with a normal left ventricular function 0.45 or less. Using the indexed geometric orifice area method, PPM was defined as nonsignificant if 1.2 cm(2)/m(2) or greater and as significant if less than 1.2 cm(2)/m(2). Using the indexed effective orifice area method, PPM was considered as nonsignificant if greater than 0.85 cm(2)/m(2), as moderate if greater than 0.65 cm(2)/m(2) and less than or equal to 0.85 cm(2)/m(2), and as severe PPM if 0.65 cm(2)/m(2) or less.

Results: The number of patients classified as having PPM differed according to the method used to predict its presence (PPM: Effective orifice area method = 72.7%; geometric method = 19.6%). Regardless of the method used to classify PPM there was no significant effect on mortality (adjusted hazard ratio: 2.65 at 1 year, 0.99 at 5 years, 0.92 at 9 years; p = not significant). The postoperative mean transvalvular gradient (17.1 ± 6.5 mm Hg) and left ventricular function (0.50 ± 0.145) improved significantly compared with the preoperative findings.

Conclusions: The method used to calculate PPM resulted in significant classification discordance. However, regardless of classification, the presence of PPM did not adversely affect long-term outcome.