The combined risk of fatal or nonfatal heart attack over the 10-year period was highest in individuals with symptomatic versus asymptomatic stenosis ( 27.5 % vs. 11.0 % ; hazard ratio [ HR ] : 2.32 , 95 % confidence interval [ CI ] : 1.298 to 4.146 , p = 0.005 ) and was higher in all patients treated with CEA ( HR : 2.27 , 95 % CI : 1.35 to 3.816 , p = 0.002 ) .