Background: A total of 25-50% of patients with stable coronary atherosclerosis treated with metallic stent implantation remain with effort angina despite optimal medical treatment and absence of stent restenosis at 1 year. The most plausible cause of persistent effort angina after stent implantation is microcirculatory dysfunction. Coronary circulation matches the myocardial blood supply and oxygen consumption. Metallic stent implantation has been related with endothelial dysfunction and impaired coronary blood flow reserve (relation between coronary blood flow at rest and maximal hyperemia) of the treated vessel at 1 year.