Journal of the American Society of Echocardiography
Volume 23, Issue 4 , Pages 380-386, April 2010

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

  • Marie-Annick Clavel, DVM, MSc

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • ,
  • Ian G. Burwash, MD

      Affiliations

    • University of Ottawa Heart Institute, Ottawa, Ontario, Canada
    • ,
  • Gerald Mundigler, MD

      Affiliations

    • Vienna General Hospital, Medical University of Vienna, Vienna, Austria
    • ,
  • Jean G. Dumesnil, MD

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • ,
  • Helmut Baumgartner, MD

      Affiliations

    • Munster General Hospital, Munster, Germany
    • ,
  • Jutta Bergler-Klein, MD

      Affiliations

    • Vienna General Hospital, Medical University of Vienna, Vienna, Austria
    • ,
  • Mario Sénéchal, MD

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • ,
  • Patrick Mathieu, MD

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • ,
  • Christian Couture, MD

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • ,
  • Rob Beanlands, MD FRCP C

      Affiliations

    • University of Ottawa Heart Institute, Ottawa, Ontario, Canada
    • ,
  • Philippe Pibarot, DVM, PhD

      Affiliations

    • Institut Universitaire de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, Laval University, Quebec, Quebec City, Canada
    • Corresponding Author InformationReprint requests: Philippe Pibarot, Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725 Chemin Sainte-Foy, Quebec, QC, G1V-4G5, Canada.

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.

Keywords: Valvular heart disease, Aortic stenosis, Left ventricular dysfunction, Stress echocardiography

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 This work was supported by grant 57445 from the Canadian Institutes of Health Research (Ottawa, ON, Canada). Dr Pibarot holds the Canada Research Chair in Valvular Heart Diseases at the Canadian Institutes of Health Research. Dr Mathieu is a research scholar at Fonds de Recherches en Santé du Québec (Montreal, QC, Canada).

PII: S0894-7317(10)00099-4

doi:10.1016/j.echo.2010.02.002

Journal of the American Society of Echocardiography
Volume 23, Issue 4 , Pages 380-386, April 2010

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