After multivariable adjustment , longer surgical duration ( odds ratio per @-minute increase , @ ; @ % confidence interval , @-@ @ ) , endoscopic vein harvesting ( odds ratio , @ ; @ % confidence interval , @-@ @ ) , poor target artery quality ( odds ratio , @ ; @ % confidence interval , @-@ @ ) , and postoperative use of clopidogrel or ticlopidine ( odds ratio , @ ; @ % confidence interval , @-@ @ ) were associated with patient-level VGF .