The main strategy of CABG is to obtain complete revascularization with the least morbidity and highest long-term patency rates. Current medical literature is conflicted regarding graft patency rates in OPCAB vs. conventional CABG. Data is also limited due to patient refusal for conventional angiography to assess grafts following surgery. Cardiac computed tomography (CT) offers a non-invasive method to assess graft patency that is 100% accurate for the diagnosis of graft patency vs. occlusion. This study is a prospective randomized controlled trial evaluating graft patency in on-pump vs. off-pump CABG using cardiac CT scanning. The study hypothesis is that graft patency rates will be equivalent between the two techniques.