Angiotensin Receptor Blockers in Aortic Stenosis

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