Usefulness of the Valvuloarterial Impedance to Predict Adverse Outcome in Asymptomatic Aortic Stenosis

ObjectivesThis study was designed to examine the prognostic value of valvuloarterial impedance (Zva) in patients with aortic stenosis (AS).BackgroundWe previously showed that the Zvais 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.MethodsWe 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).ResultsFour-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 Zvabetween 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·m2and by 2.30-fold in those with a Zvabetween 3.5 and 4.5 mm Hg·ml−1·m2after adjusting for other risk factors and type of treatment (surgical vs. medical).ConclusionsIncreased Zvais 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 Zvamay be useful to improve risk stratification and clinical decision making in patients with AS.