Coronary artery bypass graft (CABG) surgery is one of the most common major surgical procedures undertaken worldwide. Establishing the best methods for CABG is therefore a key element of successful management of patients with advanced coronary artery disease, who have narrowed coronary arteries and are at higher risk of limited exercise capacity due to angina (chest pain on exertion), myocardial infarction (heart attack), and death.
It is well established that the use of the left internal thoracic artery (arteries that supply the inner part of the chest wall) combined with vein grafts in CABG can improve life expectancy however, it is not known if there are additional benefits of routinely using the left and right internal thoracic arteries during CABG.
The ten-year outcomes of the Arterial Revascularisation Trial (ART) were published in the New England Journal of Medicine yesterday. This randomised trial compared single versus bilateral internal thoracic artery grafts in patients undergoing coronary artery bypass graft surgery. The trial tested whether routine use of two internal thoracic arteries, compared to the standard single internal thoracic artery, with all patients receiving additional vein grafts as needed, could reduce the risk of dying over a ten-year period in patients undergoing CABG surgery.
Professor Alastair Gray, one of the authors of the report, said ‘ART is one of the largest and longest duration randomised trials ever undertaken in cardiac surgery, and these results will help to guide future practice and research in this area. Meanwhile we are preparing an economic analysis of the comparative costs and outcomes of these procedures.’
Between 2004 and 2007, 3,102 patients with symptomatic coronary disease scheduled to undergo CABG were enrolled onto the trial at 28 centres in the UK, Poland, Australia, India, Brazil, Austria and Italy. A total of 1,548 patients were randomly allocated to bilateral and 1,554 patients to single internal thoracic artery grafts. Additional arterial or vein grafts were used at the discretion of the responsible surgeon. The average age of participants was 64 and 24% were women. In the bilateral graft group, 14% actually received a single internal thoracic artery graft, while 22% in the single internal thoracic artery group also received an additional radial artery graft.
Overall ART was not able to confirm that a strategy of routine bilateral internal thoracic artery grafting was superior to routine single internal thoracic artery grafting for patients undergoing CABG. Possible explanations include the high rate of patients who were randomised to receive a bilateral internal thoracic artery but actually received a single internal thoracic artery, and in those assigned a single internal thoracic artery graft about one fifth actually received an additional arterial graft in the form of a radial artery. Both factors could have reduced the true efficacy of bilateral internal thoracic artery grafts. Furthermore, a high use of guideline directed medical therapy, including aspirin, statins, beta-blockers and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, in both groups may have narrowed any potential differences between the groups.