The brachial artery flow-mediated dilation results were significantly higher on the first day after primary percutaneous coronary intervention in the preconditioning group ( Group I ) than in the control group ( Group II ) ( 12.1 % vs 0.0 % , P = .03 , and 11.1 % vs 6.3 % , P = .016 , respectively ) , and this difference remained on the seventh day ( 12.3 % vs 7.4 % , P = .0005 , respectively ) .