The purpose of this study is to determine the long-term effects of statins, atorvastatin, upon Nitric Oxide, as an endothelial function assessment, and C-Reactive Protein, an inflammatory marker, levels in patients with Peripheral Arterial Disease. These long-term biological pleiotropic effects of statins will offer information on the role of endothelial function and systemic inflammation in the etiopathogenesis of PAD.