Background Although exercise testing has been suggested to help predict clinical outcome,limited data are available to guide how exercise Doppler echocardiography (ECG) can be used clinically in asymptomatic patients with aortic stenosis (AS).The aim of this study was to assess the clinical value of exercise echocardiographic testing in asymptomatic patients with severe AS.Methods Symptom-limited treadmill exercise testing using the modified Bruce protocol was performed in 31 asymptomatic patients (mean age (62±11) years) with severe AS (aortic valve area ＜1 cm2,peak aortic velocity (AV Vmax) ＞4 m/sec,or a mean transaortic pressure gradient (AV mean PG) ＞40 mmHg (1 mmHg=0.133 kPa)) with normal left ventricular (LV)systolic function (LV ejection fraction (EF) ＞50％).Clinical symptoms,vital signs,ECG,and Doppler hemodynamics were obtained during and/or immediately after exercise.Results Aortic valve replacement (AVR) was performed in 18 patients during follow-up.The patients who had AVR exhibited higher baseline AV mean PG (51 (35-84) vs.44 (25.2-57.0) mmHg; P=0.031).There were no significant differences between the AVR group and non-AVR group including exercise duration (7.47 (2.32-11.59) vs.7.25 (4.06-10.52) minutes,P=0.917),exercise capacity (10.1 (4.6-12.8) vs.10.1 (7.0-12.8) metabolic equivalents,P=0.675),and an increment in AV mean PG by exercise (18.5 (3.2-48.0) vs.12.6 (4.4-32.1) mmHg,P=0.366).Univariate regression analysis revealed that independent determinant of AVR was the baseline AV mean PG (P=0.031).Conclusions Although additional value of exercise ECG was demonstrated,baseline transaortic mean pressure gradient is the major determinant of AVR.Further large-scale prospective studies are required to determine whether surgery should be recommended in the presence of an abnormal exercise ECG in asymptomatic severe AS.