The "Lipid Hypothesis" of CVD-stating that cholesterol is causal in the development of atherosclerotic CVD (ASCVD) and that lowering cholesterol produces lower cardiovascular event rates-is widely accepted throughout the medical community. For patients with known ASCVD (secondary prevention), studies have shown that cholesterol lowering leads to a consistent reduction in total mortality and in recurrent cardiovascular events in men and women; other studies have documented lowered mortality and events in middle-aged and older patients. Among patients without ASCVD (primary prevention), the data are generally consistent, with rates of cardiovascular events, heart disease mortality, and all-cause mortality differing among studies. Treatment guidelines have been designed to assist clinicians in selecting patients for cholesterol-lowering therapy based predominantly on their overall risk of developing CVD as well as their baseline cholesterol levels.