These hypotheses will be tested as follows: (1) custom engineered IVUS analysis software will be used to describe the geometry, composition, and spatial component relationships of the vessel, (2) the morphology of lower extremity arterial plaque, as determined by IVUS, will be correlated with baseline clinical characteristics of subjects, and (3) the effects on plaque morphology after long term treatment with antihyperlipidemics will be determined.