Aortic valve stenosis and atherosclerotic disease have several risk factors in common, in particular, hypercholesterolemia. Histologically, the diseased valves appear to have areas of inflammation much like atherosclerotic plaques. The effect of lipid-lowering therapy on the progression of aortic stenosis (AS) is unclear, and there are no randomized treatment trials evaluating cardiovascular morbidity and mortality in such patients. The Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) Study is a randomized, double-blind, placebo-controlled, multicenter study of a minimum 4 years' duration investigating the effect of lipid lowering with ezetimibe/simvastatin 10/40 mg/day in patients with asymptomatic AS with peak transvalvular jet velocity 2.5 to 4.0 m/s. Primary efficacy variables include aortic valve surgery and ischemic vascular events, including cardiovascular mortality, and second, the effect on echocardiographically evaluated progression of AS. The SEAS Study randomly assigned 1,873 patients (age 68+/-10 years, 39% women, mean transaortic maximum velocity 3.1+/-0.5 m/s) from 173 sites. Other baseline characteristics were mean blood pressure of 145+/-20/82+/-10 mm Hg (51% hypertensive); 55% were current or previous smokers; and most were overweight (mean body mass index 26.9 kg/m2). At baseline, mean total cholesterol was 5.7+/-1.0 mmol/L (222 mg/dl), low-density lipoprotein cholesterol was 3.6+/-0.9 mmol/L (139 mg/dl), high-density lipoprotein cholesterol was 1.5+/-0.4 mmol/L (58 mg/dl), and triglycerides were 1.4+/-0.7 mmol/L (126 mg/dl). The SEAS Study is the largest randomized trial to date in patients with AS and will allow determination of the prognostic value of aggressive lipid lowering in such patients.