1.2 Sample size To calculate the number of patients we used the site: www.lei.dante.br-pesquisa. The sample will be composed of 25 patients in each arm. The number of patients per group necessary to detect a difference in reactive hyperemia index (RHI) of 0.3 with a power of 80% is 25 patients. And with a two-tailed t test at the 5% level it was calculated to be 21, with SD of 0.35 for the difference in RHI. The RHI improvement by 0.3 was based on previous study and a drop out rate of 20% was considered.