Inclusion Criteria:  Mild to moderate aortic stenosis (peak aortic jet velocity ≥2.5 and <4m/s) Normal left ventricular ejection fraction (i.e. ≥50%) Systolic blood pressure >110 mmHg Diastolic blood pressure >70 mmHg  Exclusion Criteria:  More than mild aortic or mitral regurgitation, or mitral stenosis Current use or documented indication for renin-angiotensin system medication or Aliskiren Known allergy or intolerance to angiotensin II receptor blockers (ARBs) Alzheimer, dementia or known non-compliant patient Renal dysfunction (glomerular filtration rate <30ml/min/1.73m2) Chronic hyperkalemia Diagnosed hepatic failure, cirrhosis, hepatitis or history of hepatic impairment Newly diagnosed (<2 months) or poorly controlled diabetes Pre-existing obstructive coronary artery disease with CCS III-IV angina or recent myocardial infarction (<3 months) Pregnant or lactating women Patients unable to read, understand or sign research consent