Coronary artery disease (CAD) is one of the commonest diseases in the western world, with >100,000 deaths a year in the UK. It occurs as a result of mismatch between supply and demand of oxygen, usually due to atherosclerotic narrowing of one or more of the major coronary arteries. CAD can remain asymptomatic initially as the stenosis caused by the plaques may not be flow-limiting. As it progresses with time, patients present with angina, acute coronary syndromes or even sudden death. Treatment can be medical or surgical, including percutaneous coronary intervention (PCI) and/or Coronary artery bypass grafting (CABG). CABG provides a safe and effective treatment for a large number of people with coronary artery disease for whom PCI and medications are unsatisfactory. With overall improvement in technique and perioperative care, patients undergoing these procedures have prognostic and symptomatic benefit.