The first randomized trials on the subject were conducted in the late 1970s, demonstrating that aspirin was safe for use in the postoperative period. However, no benefit was seen in terms of graft patency in these early studies because of limited trial enrollment and late admin- istration, typically 3 days after surgery.11 13 In one of the first studies assessing aspirin administration within the early hours after surgery, Chesebro et al14 conducted a controlled trial comparing graft patency in 407 patients randomized to placebo or the combination of aspirin and dipyridamole beginning as early as 7 hours after surgery. Within 1 month of surgery, vein graft patency was significantly higher in patients treated with antiplatelet therapy (98% versus 90%, aspirin and dipyridamole versus placebo; P<0.0001). In a subsequent report, the authors noted an improvement in vein graft patency with antiplatelet therapy 1 year after surgery (89% versus 77%, aspirin and dipyridamole versus placebo; P<0.0001). Antiplatelet therapy was also shown to prevent the development of late vein graft occlusions in those patients whose grafts were documented as patent at the 1-month time point (6% versus 14% late occlusion rate, aspirin and dipyri- damole versus placebo; P=0.02).15 The largest placebo-controlled trial to date, the Veterans Administration Cooperative Study, randomized 772 CABG patients to several postoperative aspirin regimens admin- istered for 1 year. Within 60 days of surgery, 555 patients (1781 grafts) underwent angiographic graft assessment, revealing the following graft patency rates: aspirin 325 mg daily, 93.5%; aspirin 325 mg 3 times daily, 92.3%; and aspi- rin 325 mg and dipyridamole 75 mg 3 times daily, 91.9%. 