Increasing transvalvular flow with passive leg rise as an add-on to dobutamine in patients with paradoxical low-flow, low-gradient aortic stenosis

Abstract

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Gottfried und Julia Bangerter-Rhyner Foundation Background Projected aortic valve area (AVA), used in case of low-flow, low-gradient aortic stenosis is reliable if the transvalvular flow can be substantially augmented. Moreover it depends on the calculated valve compliance, which should remain constant, irrespective of the change in transvalvular flow. Methods We prospectively compared 3 different stress methods to increase transvalvular flow in patients with low-flow, low-gradient aortic stenosis: maximal dobutamine infusion rate ("Dmax"), passive leg-raise ("PLR") and the combination of the two ("Dmax + PLR") with the velocity time integral (VTI) method. The primary endpoint was the percentage of patients with ΔQ ≥20%. The percentage of patients with the pseudosevere classification and the mean slope between transvalvular flow and AVA - corresponding to the valve compliance - for each stress methods were the secondary endpoints. Results "Dmax + PLR" yielded the highest percent of patient with Δtransvalvular flow ≥20% implying the highest validity to the projected AVA between all the stress methods. In the "Paradox" group (LVEF ≥50%, n = 25), the percentage of patients classified as pseudosevere aortic stenosis was the lowest using "Dmax + PLR". This was also the case in the "lowEF" group with the Simpson’s method (LVEF <50%, n = 20). The mean slope of Q with respect to AVA consistently decreased with higher Δtransvalvular flow. Conclusion Projected AVA was obtained with the highest reliability with the "Dmax + PLR" stress method. This same stress method yielded the lowest percentage of classification in pseudosevere in the "Paradox" group. This implies that the valve compliance, capturing the relationship between transvalvular flow and AVA might be non-constant and rather inversely proportional to translvalvular flow. Abstract Figure. Echo parameters and classification Abstract Figure. Projected AVA and valve compliance