Validation of conventional and simplified methods to calculate projected valve area at normal flow rate in patients with low flow, low gradient aortic stenosis : the multicenter TOPAS (True or Pseudo Severe Aortic Stenosis) study

Authors: Clavel, Marie-Annick; Burwash, Ian G.; Mundigler, Gerald; Dumesnil, Jean G.; Baumgartner, Helmut; Bergler-Klein, Jutta; Sénéchal, MarioMathieu, PatrickCouture, Christian; Beanlands, Robert S. B.; Pibarot, Philippe
Abstract: Background : It has been previously demonstrated that a new index of aortic stenosis (AS) severity derived from dobutamine stress echocardiography (DSE), the projected aortic valve area (AVA) at a normal transvalvular flow rate (AVAproj), is superior to traditional Doppler echocardiographic indices to discriminate true severe from pseudosevere low-gradient AS. The objectives of this study were to prospectively validate the diagnostic and prognostic value of AVAproj in a large series of patients and to propose a new clinically applicable simplified method to estimate AVAproj. Methods : AVAproj was calculated in 142 patients with low-flow AS using 2 methods. In the conventional method, AVA was plotted against mean transvalvular flow (Q) at each stage of DSE, and AVA at a standardized flow rate of 250 ml/s was projected from the slope of the regression line fitting the plot of AVA versus Q: AVAproj = AVArest + slope × (250 - Qrest). In the simplified method, using this equation, the slope of the regression line was estimated by dividing the DSE-induced change in AVA from baseline to the peak stage of DSE by the change in Q. Results : There was a strong correlation between AVAproj calculated by the two methods (r = 0.95, P < .0001). Among the 142 patients, 52 underwent aortic valve replacement and had underlying AS severity assessed by the surgeon. Conventional and simplified AVAproj demonstrated similar performance in discriminating true severe from pseudosevere AS (percentage of correct classification of AVAproj = 1 cm2, 94% and 92%, respectively) and were superior to traditional dobutamine stress echocardiographic indices (percentage of correct classification, 60%-77%). Both conventional and simplified AVAproj correlated well with valve weight (r = 0.52 and r = 0.58, respectively), whereas traditional dobutamine stress echocardiographic indices did not. In the 84 patients who were treated medically, conventional AVAproj = 1.2 cm2 (hazard ratio, 1.65; P = .02) and simplified AVAproj = 1.2 cm2 (hazard ratio, 2.70; P < .0001) were independent predictors of mortality. Traditional dobutamine stress echocardiographic indices were not predictive. Conclusion : In patients with low-flow AS, AVAproj better predicts underlying AS severity and patient outcomes than traditional dobutamine stress echocardiographic indices. Simplified AVAproj is easier to calculate than conventional AVAproj, facilitating the use of AVAproj in clinical practice.
Document Type: Article de recherche
Issue Date: 1 April 2010
Open Access Date: Restricted access
Document version: VoR
This document was published in: Journal of the American Society of Echocardiography, Vol. 23 (4), 380–386 (2010)
C.V. Mosby
Alternative version: 10.1016/j.echo.2010.02.002
Collection:Articles publiés dans des revues avec comité de lecture

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