Background Current guidelines recommend statin therapy after coronary artery bypass grafting (CABG) to attain low-density lipoprotein (LDL) levels less than 100 mg/dL. Whether achieving LDL levels less than 70 mg/dL improves postoperative graft patency remains unknown. Methods The CASCADE (Clopidogrel after Surgery for Coronary Artery Disease) trial was a randomized study that evaluated the addition of clopidogrel to aspirin on the development of saphenous vein graft disease after CABG. Patients received the standard of care regarding postoperative statin therapy with targeted LDL levels less than 100 mg/dL. Twelve months postoperatively, patients returned for a coronary angiogram and saphenous vein graft (SVG) intravascular ultrasonogram. In this post hoc analysis, the impact of statin therapy on graft patency and vein graft intimal hyperplasia was assessed. Results LDL levels significantly declined over the period of the trial ( p = 0.002). Twelve months postoperatively, 58.4% patients achieved LDL levels less than 70 mg/dL. Twelve-month graft patency was higher for patients with LDL levels less than 100 mg/dL (96.5%) compared with patients with LDL levels >100 mg/dL (83.3%, p = 0.03), even after adjustment in multivariate analysis (odds ratio [OR], 5.2; 95% confidence interval [CI], 1.3–21.6; p = 0.02). However, no improvement in graft patency was noted with further LDL reduction to less than 70 mg/dL (p = 1.00). Consistent statin use throughout the trial period was independently associated with less vein graft intimal hyperplasia documented by intravascular ultrasound at 12 months (p = 0.04). Conclusions Statin therapy to achieve LDL levels less than 100 mg/dL was independently associated with improved graft patency in the CASCADE trial. Randomized clinical trials are warranted to prospectively evaluate postoperative LDL reduction to less than 70 mg/dL and its impact on graft patency after CABG.