Coronary Artery Bypass Graft Surgery (CABGS) is commonly used to treat patients with coronary artery disease (atherosclerosis) for the relief of angina (chest pain) and improve heart muscle function.

Healthy veins or arteries, referred to as ‘conduits’ from elsewhere in the patient's body are grafted (attached) from the aorta to the coronary arteries, bypassing (via new routes) coronary artery narrowings caused by atherosclerosis (hardening of the arteries) and thereby improving the blood supply to the myocardium (heart muscle).

Over the years, a range of different veins and arteries from around the body have been used to bypass diseased coronary arteries. Typically, the saphenous veins from the legs and internal thoracic arteries from behind the breastbone are used for bypass. More recently, radial arteries from the forearm have also been used to bypass coronary arteries that are diseased (atherosclerotic). There is strong evidence to indicate that the left internal thoracic artery stays open the longest (i.e. has the highest patency) and achieves the best health outcomes. As a result, most cardiac surgeons use the left internal thoracic artery as their first choice of conduit (vessel used to bypass the blocked artery). However, many patients require multiple grafts and there is little evidence as to which grafts are best conduits to use.

It has been suggested that the radial arteries might function better than saphenous veins as conduits. The Radial Artery Graft Study aims to compare patency of the radial arteries with saphenous veins and the right internal thoracic artery.

The Department of Cardiac Surgery at Austin Health is conducting a prospective randomised trial, comparing the performance of the radial artery with the right internal mammary artery and the saphenous vein graft, in patients requiring coronary artery bypass surgery.

The study was first given approval by the Austin Health Human Research Ethics Committee in 1995 for a ten-year period. Enrolment commenced in March 1996. Recruitment ceased in March 2005. Patients were randomly assigned to the control or experimental group. Patients in both groups received the left internal thoracic artery as their first graft. Those in the control group received either a right internal thoracic artery or saphenous vein graft as their second graft. Those in the experimental group received a radial artery graft as their second graft.

The gold standard measure for the comparison of conduits is through the use of post-operative angiograms. These angiograms assess how patent (open) the grafts are, and also offer quality assurance of the CABG surgery performed. The angiograms are randomly allocated/ scheduled at 1, 2, 5, 7.5 or 10 years after bypass surgery.Participants are also offered an elective coronary angiogram (or a Multi slice CT coronary angiogram scan, should they refuse the standard coronary angiogram) at 5 & 10 years after their surgery. Clinical data is systematically collected to determine those patients who experience heart attack, repeat surgery, balloon angioplasty or death over subsequent years.

• Coronary Artery Disease
• Atherosclerosis

Inclusion Criteria:

• The patient is scheduled for primary coronary artery bypass surgery alone ie. no reoperations, no associated procedures
• The patient requires more than 1 graft, that is, there are at least 2 coronary artery stenoses of > 70%.

Exclusion Criteria:

• Renal disease with a creatinine >0.30 mmol/L.
• Chronic heart failure (NYHA Class III or IV or ejection fraction <35% on angiography or radionuclide ventriculography).
• Associated major illnesses e.g., malignancy.
• Body mass index (BMI) > 35; weight (kg)/height(m2).
• Acute presentation, that is, those patients who have an acute myocardial infarct within one week prior to surgery or who present with cardiogenic shock.
• Technical exclusions e.g. sequential grafting.
• Failure to obtain informed consent.
• Off pump.

GROUP 1 Specific exclusions

• Failure to use radial artery due to abnormal Allen Test (>10 sec)
• Failure to be able to use the FRIMA eg. Chest trauma
• FEV1 < 50% of expected value
• Diabetic patients (IDDM or NIDDM) >60 years
• Patients >70 years

GROUP 2

• Specific exclusions
• Failure to use radial artery due to abnormal Allen Test (>10 sec)
• Failure to be able to use the saphenous vein eg. Varices, past trauma
• Diabetic patients <60
• Other patients <70