Asymptomatic patients may exhibit symptoms during objective exercise testing, but whether symptoms are due to the obstructivity 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. The aim of this study was to examine the echocardiographic predictors of exercise ability during cardiopulmonary exercise testing combined with stress echocardiography.
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 VO2peak. Echocardiography was measured at rest and during maximal exercise (defined as RER>1)
VO2peak showed a poor relationship with conventional resting parameters of severity including peak velocity (rho=0.07; p=ns), mean pressure gradient (rho=0.3; p=ns), AVA (rho=0.4; p=ns), dimensionless index (rho=0.05; p=ns), resting systolic function (by EF (rho=−0.18; p=ns) and TDI (rho=0.39; p=ns). During exercise systolic augmentation had a good relationship with exercise ability (rho=0.77; p<0.0001) but the relationship with exercise mean gradient was weaker (rho=0.57; p=0.005) and there was no relationship with exercise LVEF (rho=0.18; p=ns).
Longitudinal systolic function during peak exercise is the strongest predictor of exercise ability when compared to conventional measures of severity of aortic stenosis.