Keywords: aortic stenosis; aortic valve area index; circle; computed axial tomography; continuity equation; coronary artery disease; elliptical geometry; low flow aortic stenosis; magnetic resonance imaging; medical management; observation; pressure gradient; rheumatic heart disease; stroke volume index; three dimensional echocardiography; transaortic flow; transcatheter aortic valve replacement; valvular heart disease guidelines.