The purpose of this study is to compare graft patency rates following coronary artery bypass graft surgery performed by beating heart vs. conventional techniques using cardiac CT scanning to evaluate the bypass grafts.

The issue of whether to perform conventional CABG or off-pump CABG continues to be the subject of debate. Controversy remains regarding the appropriateness of applying OPCAB to all patients as opposed to selected sub-populations.

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.

Inclusion Criteria:

• Surgery indicated
• Patient is hemodynamically stable
• Isolated coronary artery surgery (no valve)
• No contraindications to cardiopulmonary bypass
• No previous surgery (not redo CABG)

Exclusion Criteria:

• critically ill patient with hemodynamic instability.
• concomitant cardiac procedures.
• inability to provide written informed consent.
• prior severe reaction to contrast dye :
• life-threatening anaphylactoid reactions
• cardiac dysrhythmias and arrest
• cardiovascular and pulmonary collapse
• elevated serum creatinine (>150 mmol/L).
• contraindications to cardiopulmonary bypass.
• Age < 18 years .