Aortic stenosis is the most common valvular disease in the Western World. It is a slow evolving degenerative disease caused by gradual accumulation of calcium in the valve. Untreated it is fatal. Reduced opening area of the valve increases afterload on the left ventricle (LV), which leads to raised end-diastolic pressure in the LV. Increased wall stress leads to LV hypertrophy and expansion of the extracellular matrix. An abnormally high extracellular volume fraction is called myocardial fibrosis (MF), which causes increased LV stiffness, diastolic dysfunction, dilatation of the left atrium and in the end heart failure.