Abstract 3388: Usefulness Of The Valvulo-arterial Impedance To Predict Adverse Outcome In Aortic Stenosis
Background. We recently proposed a new index: the valvulo-arterial impedance (Zva), which represents the valvular and arterial hemodynamic factors that oppose ventricular ejection. This index is calculated by dividing the estimated left ventricule (LV) systolic pressure (systolic arterial pressure + mean transvalvular gradient) by the stroke volume indexed for the body surface area. We previously demonstrated that Zva is superior to standard indices of aortic stenosis (AS) severity in estimating the global LV afterload and predicting the occurrence of LV dysfunction.
Objective: to assess the usefulness of Zva to predict adverse outcome in AS.
Methods. We retrospectively analyzed clinical and echocardiographic data of 544 consecutive patients (320 men and 224 women; mean age: 70±14 years) having at least moderate AS (aortic jet velocity ≥2.5m/s) and no symptoms at baseline. The primary end-point for this study was the occurrence of aortic valve replacement (AVR) or death.
Results. The mean follow-up time was 2.5±1.8 years. Ninety one patients (17%) died and 176 (32%) had aortic valve replacement (AVR) during follow-up. The 3-year event-free survival was significantly lower in patients (n=180, 33%) with Zva ≥ 4.5 mmHg.ml−1.m−2 compared to those (n=192, 35%) with Zva between 3.5 and 4.5, and those (n=172, 32%) with Zva ≥ 3.5: respectively 33±5% vs 51±4% and 56±5%, p<0.001. A value of Zva ≥ 4.5 was associated with an age-adjusted risk of adverse event of 1.3 (95% confidence interval: 1.1–1.6, p=0.0015). On multivariate analysis, the independent predictors of the event-free survival were: peak aortic jet velocity (p<0.001), coronary artery disease (p=0.001) and Zva (p=0.03). Two-year overall survival was also significantly (p=0.001) lower in the patients with a baseline Zva ≥ 4.5 (70±5%) compared to those with Zva between 3.5 and 4.5 (80±3 %) and those with Zva ≤ 3.5 (88±3 %).
Conclusion. A value of valvulo-arterial impedance ≥ 4.5 mmHg.ml−1.m−2 identifies patients with a poor outcome. These findings suggest that beyond standard indices of stenosis severity, the consideration of valvulo-arterial impedance may be useful to improve risk stratification and clinical decision making in patients with AS.