Abstract 17374: Assessment of Aortic Stenosis Severity in Low-Flow Low-Gradient Aortic Stenosis: Comparison of Dobutamine Stress Echocardiography and Aortic Valve Calcium Scoring by Computed Tomography -The TOPAS Study-
Background: In patients with low-flow, low-gradient aortic stenosis (LF-LG AS), dobutamine stress echocardiography (DSE) is helpful to differentiate true versus pseudo severe stenosis. However, the findings of DSE often remain inconclusive, particularly in patients with incomplete normalization of flow with dobutamine. The projected aortic valve area at normal flow rate (AVAproj) has been proposed to improve the assessment of stenosis severity in these patients but this new parameter has only been validated in a small subset of patients using the weight of the aortic valve explanted at the time of surgery. Aortic valve calcification (AVC) measured by multidetector computed tomography (MDCT) has been shown to be an accurate, flow-independent, marker of stenosis severity. The objective of this study was to examine the relationship between resting and DSE parameters of stenosis severity and AVC measured by MDCT in patients with LF-LG AS.
Methods: 30 patients (age: 73 ±10 years, 73% men) with LF-LG AS (stroke volume index<35 mL/m2, mean gradient <40 mmHg, and aortic valve area (AVA) ≤0.6 cm2/m2) with either reduced (i.e. classical low flow; n=12) or preserved (i.e. paradoxical low flow; n=18) left ventricular ejection fraction (LVEF) were prospectively enrolled in the TOPAS study and underwent DSE and MDCT. AVC was measured by Agatston method and expressed in arbitrary units (AU).
Results: AVC correlated well with AVAproj (r=-0.60; p=0.0009) and indexed AVAproj (r=-0.76; p<0.0001), but only moderately with peak stress gradient (r=0.36, p=0.04). There was no correlation between AVC and rest AVA or peak stress AVA (all p>0.4). AVC correlated strongly with aortic valve weight in the subset of patients undergoing aortic valve replacement (r=0.94; p=0.0006).
Conclusion: The findings of this study suggest that the DSE parameters of peak stress gradient and AVA proposed in the ACC-AHA guidelines have limited accuracy to assess underlying stenosis severity in patients with LF-LG AS. AVAproj appears superior to these parameters for differentiating true versus pseudo-severe AS. Quantification of AVC by MDCT may be useful to corroborate stenosis severity when measurement of AVAproj is not feasible.
Author Disclosures: A. Dahou: None. M. Clavel: None. E. Larose: None. R. Capoulade: None. P.E. Bartko: None. H.B. Ribeiro: None. L. Tastet: None. J. Bergler-klein: None. G. Mundigler: None. I. Burwash: None. J.G. Dumesnil: None. M. Senechal: None. K. O’Connor: None. H. Baumgartner: None. J. Rodés-Cabau: None. P. Pibarot: None.
- © 2014 by American Heart Association, Inc.