P544The importance of contractile reserve when assessing asymptomatic patients with aortic stenosis

Asymptomatic patients may exhibit symptoms during objective exercise testing, but whether symptoms are due to the obstructively of the valve (typified by the mean gradient) or underlying ventricular function remains unknown. While the mean gradient is an easy parameter to measure no consensus about the measurement of contractile reserve exists. Longitudinal abnormalities may occur in the presence of a normal ejection fraction and the augmentation of these parameters is poorly described. To obtain an objective regarding patients exercise ability is best determined using cardiopulmonary exercise testing. We therefore examined echocardiographic predictors of exercise ability during cardiopulmonary exercise testing. 24 asymptomatic patients with moderate to severe or severe aortic stenosis and preserved ejection fraction underwent stress echocardiography with simultaneous cardiopulmonary exercise testing. The primary assessment of exercise ability was the VO2peak and OUES. Echocardiography was measured at rest and during maximal exercise (defined as RER > 1) OUES and VO2peak showed a poor relationship with conventional parameters of severity including peak and mean gradients, AVA and dimensionless index, resting systolic function (by EF and TDI). During exercise systolic augmentation had a good relationship with exercise ability but the exercise mean gradient and exercise LVEF did not. Longitudinal systolic function and particularly systolic augmentation is the strongest predictor of exercise ability when compared to conventional measures of severity. VO2peak OUES S' exercise Rho=0.69 (p=0.001) R= 0.71 (p=0.001) S' rest Rho=0.52 (p=0.01) R= 0.44 (p=ns) Rest AV max V Rho= 0.09 (p=ns) R= -0.08 (p=ns) Rest AV mean PG Rho= 0.34 (p=ns) R=-0.10 (p=ns) Exercise AV max V Rho=0.43 (p=0.05) R=0.23 (p=ns) Exercise AVmean PG Rho= 0.51 (p=0.001) R=0.26 (p=ns) Rest AVA Rho=0.40 (p=ns) Rho=0.46 (p=0.04) Dimensionless index Rho=0.15 (p=ns) R=0.13 (p=ns) LVEF rest Rho=-0.18 (p=ns) R=-0.32 (p=ns) LVEF exercise Rho=0.18 (p=ns) R=0.17 (p=ns) S' - systolic velocity; V - velocity; AV - aortic valve; AVA- aortic valve area; LVEF - left ventricular ejection fraction