The narrowed valve prevents the outflow of the left ventricle. This results in left ventricular hypertrophy, which over time if it is not treated, will lead to increased pressure and volume in the left atrium and ultimately cause pulmonary HTN and edema. Forward flow (out of the aorta) may be decreased and can result in syncope or chest pain. The hypertrophic changes may lead to heart failure if this is not treated.