Treadmill exercise in apparently asymptomatic patients with moderate or severe aortic stenosis: relationship between cardiac index and revealed symptoms

Abstract

Objectives To test whether symptoms revealed on exercise testing in patients with moderate or severe aortic stenosis are associated with changes in left ventricular systolic function and to investigate the ability of resting measures to predict peak cardiac index.

Methods In a prospective study of asymptomatic aortic stenosis, 38 patients with a median age of 63 years (range 29–83) and an effective aortic orifice area by the continuity equation of less than 1.5 cm² had echocardiography, measurement of blood B-type natriuretic peptide (BNP) level and exercise haemodynamic testing using an inert gas rebreathing device.

Results Revealed symptoms occurred in 10 patients in whom peak cardiac index (p=0.002), stroke index (p=0.024) and maximum oxygen consumption (VO₂) (p=0.003) were lower than in those without symptoms. Univariate predictors of peak cardiac index were Doppler tissue peak systolic velocity (p=0.004, r=0.45), the ratio of peak transmitral E velocity to Doppler tissue Ea velocity (p=0.039, r=−0.34) and log BNP (p<0.001, r=−0.71). The only independent predictor of peak cardiac index was the log BNP level (p<0.001, r=−0.71).

Conclusions Revealed symptoms on treadmill exercise in apparently asymptomatic aortic stenosis were associated with lower peak myocardial VO₂ and lower peak stroke index during exercise. The strongest resting predictor of revealed symptoms and of peak cardiac index was the blood BNP level.