Subjects with severe symptomatic aortic stenosis defined as aortic valve area of less than 1 cm2 or index area of 0.6 cm2/m2 by echocardiography, together with low-gradient (mean gradient across the aortic valve <40 mmHg) who are referred for treatment of AS will be recruited. A total of up to 100 consecutive subjects of both genders will be enrolled at the Sheba Medical Center. The study procedures, clinical management and follow up will be done at the Sheba Medical Center.