In patients who present with acute coronary syn- drome, it is reasonable to administer combination antiplatelet therapy after CABG with aspirin and either prasugrel or ticagrelor (preferred over clopi- dogrel), although prospective clinical trial data from CABG populations are not yet available (Class IIa; Level of Evidence B). 5. As sole antiplatelet therapy after CABG, it is rea- sonable to consider a higher aspirin dose (325 mg daily) rather than a lower aspirin dose (81 mg daily), presumably to prevent aspirin resistance, but the benefits are not well established (Class IIa; Level of Evidence A). 6. Combination therapy with both aspirin and clopi- dogrel for 1 year after on-pump CABG may be con- sidered in patients without recent acute coronary syndrome, but the benefits are not well established (Class IIb; Level of Evidence Level A). Antithrombotic Therapy In the early years of coronary bypass graft surgery, before the introduction of routine aspirin use in the 1980s, a need was recognized for adjunctive pharmacotherapy to improve patency and to prevent thrombosis of bypass grafts after CABG. With the hypothesis that anticoagulation could reduce the likelihood of graft occlusion, several trials were performed to evaluate the role of anticoagulation with warfarin, a vitamin K antagonist. In 1979, in one of the first trials on the subject, Pantely et al11 found no improvement in graft patency among CABG patients treated with warfarin. Two subsequent stud- ies suggested some benefit associated with warfarin treatment, but aspirin treatment had yet to be incorporated into everyday practice at that time.12,67 In the largest trial in the field, the Post-Coronary Artery Bypass Graft (Post-CABG) trial ran- domized 1351 patients to low-dose warfarin anticoagulation (mean international normalized ratio, 1.4) or placebo, with all patients receiving aspirin 81 mg daily. 