19 Sep 10

Usefulness of the valvuloarterial impedance to predict adverse outcome in asymptomatic aortic stenosis

Posted in Echocardiography, Valvular disease at 0:22 by Laci

By Z Hachicha, J Dumesnil, P Pibarot

JACC 2009;54:1003-1011

This study was designed to examine the prognostic value of valvuloarterial impedance (Zva) in patients with aortic stenosis (AS).

We previously showed that the Zva 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 =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 Zva =4.5 mm Hg∑ml-1∑m2 (65 ± 5%) compared with those with Zva between 3.5 and 4.5 mm Hg∑ml-1∑m2 (78 ± 4%) and those with Zva =3.5 mm Hg∑ml-1∑m2 (88 ± 3%). The risk of mortality was increased by 2.76-fold in patients with Zva =4.5 mm Hg∑ml-1∑m2 and by 2.30-fold in those with a Zva between 3.5 and 4.5 mm Hg∑ml-1∑m2 after adjusting for other risk factors and type of treatment (surgical vs. medical).

Conclusions
Increased Zva 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 Zva may be useful to improve risk stratification and clinical decision making in patients with AS.

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