This is a prospective, single-center study assessing the effect of atorvastatin 40 mg/day (Lipitor, Pfizer) on the progression of calcific aortic stenosis in approximately 70 patients with mild to moderate calcific AS of a tricuspid or bicuspid aortic valve. As a control population, published data on historical AS cohorts will be used, employing the accepted rate of progression of a decrease in aortic valve area of 0.1 cm²/year. Additionally, also for comparison, we will prospectively study a registry of AS patients who meet our entry criteria but are either currently already being treated with or refuse to take an HMG-CoA reductase inhibitor (referred to as the "standard care" group).