title: Usefulness of the valvuloarterial impedance to predict adverse outcome in asymptomatic aortic stenosis.
abstract: OBJECTIVE
  This study was designed to examine the prognostic value of valvuloarterial impedance (Z(va)) in patients with aortic stenosis (AS).
  
  
  BACKGROUND
  We previously showed that the Z(va) is superior to standard indexes of AS severity in estimating the global hemodynamic load faced by the left ventricle (LV) and predicting the occurrence of LV dysfunction. This index is calculated by dividing the estimated LV systolic pressure (systolic arterial pressure + mean transvalvular gradient) by the stroke volume indexed for the body surface area.
  
  
  METHODS
  We retrospectively analyzed the clinical and echocardiographic data of 544 consecutive patients having at least moderate AS (aortic jet velocity > or =2.5 m.s(-1)) and no symptoms at baseline. The primary end point for this study was the overall mortality regardless of the realization of aortic valve replacement (AVR).
  
  
  RESULTS
  Four-year survival was significantly (p < 0.001) lower in the patients with a baseline Z(va) > or =4.5 mm Hg x ml(-1) x m(2) (65 +/- 5%) compared with those with Z(va) between 3.5 and 4.5 mm Hg x ml(-1) x m(2) (78 +/- 4%) and those with Z(va) < or =3.5 mm Hg x ml(-1) x m(2) (88 +/- 3%). The risk of mortality was increased by 2.76-fold in patients with Z(va) > or =4.5 mm Hg x ml(-1) x m(2) and by 2.30-fold in those with a Z(va) between 3.5 and 4.5 mm Hg x ml(-1) x m(2) after adjusting for other risk factors and type of treatment (surgical vs. medical).
  
  
  CONCLUSIONS
  Increased Z(va) is a marker of excessive LV hemodynamic load, and a value >3.5 successfully identifies patients with a poor outcome. These findings suggest that beyond standard indexes of stenosis severity, the consideration of Z(va) may be useful to improve risk stratification and clinical decision making in patients with AS.
authors.affiliation: Institut Universitaire de Cardiologie et de Pneumologie de Québec/Québec Heart and Lung Institute, Department of Medicine, Laval University, Québec City, Québec G1V 4G5, Canada.
authors.forename: Zeineb
authors.initials: Z
authors.lastname: Hachicha
authors.forename: Jean G
authors.initials: JG
authors.lastname: Dumesnil
authors.forename: Philippe
authors.initials: P
authors.lastname: Pibarot
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology*; D001783:Blood Flow Velocity; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D013318:Stroke Volume / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology*; D055815:Young Adult