Abstract 13023: Differential Correlation Between Measures of Severity of Aortic Valve Stenosis and Body Size
Background: Jet velocity (Vmax), mean pressure gradient (MPG), and aortic valve area (AVA) are commonly used measures for the assessment of the severity of aortic valve stenosis with, for example, severe stenosis defined by a Vmax >4.0m/s, MPG >40mmHg, and an AVA<1.0 cm2. Since patients of different body size require different valve areas, a cut-off value indexed to body surface area (AVAindex<0.6cm2/m2) is often preferred. Albeit widely adopted in the literature, very limited information is available on the validity of indexing aortic valve area by body surface area particularly in patients with valve stenosis; and, in fact, this approach has repeatedly been questioned. We therefore set out to investigate the need for and the effects of indexation by measures of body size in patients with significant aortic valve stenosis.
Methods and Results: Echocardiographic and anthropometric data from 2913 consecutive patients with a jet velocity ≥2.5m/s and normal left ventricular function were analysed. Forty-eight percent were female, mean age 73±10years, body surface area 1.9±0.2m2, Vmax 4.1±0.9m/s, MPG 40.4±17.6mmHg, AVA 0.89±0.32cm2, and AVAindex 0.47±0.16cm/m2. Jet velocity and MPG were independent of body surface area as indicated by a correlation coefficient of 0.072 and 0.073, respectively. In contrast, calculation of AVA based on the continuity equation introduced a significant correlation with body surface area (r=0.312, p<0.001) to the effect that larger patients presented with a larger AVA (less severe stenosis). In turn, linear adjustment of AVA by body surface area (AVAindex) effectively eliminated the correlation between AVA and BSA (r=0.003).
Conclusion: Jet velocity as a measure of aortic valve stenosis is independent of body surface area. Calculation of AVA introduces a significant correlation with body size which can be removed by indexing for body surface area.
- © 2011 by American Heart Association, Inc.