The clinical and prognostic benefits of coronary artery bypass grafting (CABG) for certain subgroups of patients with ischaemic heart disease are well established.1 Most patients have three vessel coronary artery disease and the conventional CABG operation uses a single internal mammary artery (IMA) and two vein grafts to perform three bypass grafts. This procedure provides excellent short and intermediate term outcome but is limited, in the long term, by vein graft failure. Ten years after CABG 95% of IMA grafts are patent and disease free whereas three quarters of vein grafts are severely diseased or blocked.

The case for one arterial graft
For over a decade the superior patency of a single IMA over vein grafts has been known to improve survival and to reduce the incidence of late myocardial infarction, recurrent angina and the need for further cardiac interventions.

The case for two arterial grafts Substantial evidence for the prognostic and clinical benefits of both IMA grafts has recently been reported in a large study from the Cleveland clinic.3 In comparison to the use of a single IMA graft, use of both IMA grafts resulted in a further significant improvement in survival (with a reduction in mortality by 10% at 10 years) and a fourfold reduction in the need for reoperation. Furthermore, these benefits extended across all groups of patients with a five year life expectancy including “elderly” patients (up to mid-seventies), and those with diabetes and impaired ventricular function. The major concern of harvesting both IMA is an increase in sternal wound complications. This can be avoided by a skeletonisation rather than a pedicled technique which leaves collateral vessels intact on the sternum and allows the safe use of both IMAs even in diabetic patients.

The case for three arterial grafts
Several arteries have been proposed as the third arterial graft and the most widely used is the radial artery. The radial artery is a versatile conduit, which can be harvested easily and safely, has handling characteristics superior to those of other arterial grafts and comfortably reaches any coronary target. For the patient it offers the prospect of superior graft patency compared to saphenous vein grafts4 as well as improved wound healing. The potential impact of the radial artery on survival is not yet established as it has only been in widespread use for five years.

Finally, many patients are interested to know “how long grafts are likely to last”. This may be viewed most helpfully in terms of event rates, rather than physical lack of occlusion of a graft: “ischaemic event rate” (5% per year) and cardiac mortality (2–2.5% per year). A recurrent “event” (death, MI or recurrence of angina) occurs in 25% of surgically treated patients in <5 years, and 50% at 10 years.

In summary, the use of arterial grafts offers substantial short and long term clinical and prognostic benefits. In particular the use of both IMA grafts significantly reduces mortality and the need for re-operation. Current evidence suggests that the superior patency of arterial grafts also reduces perioperative mortality by reducing perioperative myocardial infarction. This is particularly true in patients with smaller or more severely diseased coronary arteries (females, diabetics, Asian background) where discrepancy between the size of vein grafts and coronary vessels leads to “runoff” problems and a predisposition to graft thrombosis. Careful harvesting of both IMAs can be performed even in diabetic patients without an increase in wound healing problems. Relative contraindications to arterial grafts are patients who are likely to require significant inotropic support in the postoperative period (because of the risk of graft vasoconstriction) or those with severely impaired ventricular function (ejection fraction less than 25%) and limited life expectancy.

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