Data suggests BIMA improves coronary artery bypass graft efficiency

Aug 31 2010

Recent trial data indicate that coronary artery bypass graft (CABG) surgery remains the most effective intervention for patients with severe coronary artery disease (CAD). Moreover, for over two decades it has been recognised that the use of a single internal mammary artery (SIMA) during CABG improves survival and freedom from myocardial infarction, recurrent angina and repeat intervention. While most patients need three or four bypass grafts, revascularisation can usually be effectively achieved with a combination of SIMA and supplementary vein grafts. However, while internal mammary arteries tend to remain patent almost indefinitely, there is a constant attrition of vein grafts such that by ten years after the operation half of the vein grafts are occluded and half of the remainder are severely diseased; by contrast more than 90% of the internal mammary arteries are still patent. 

Observational data have also suggested that use of bilateral internal mammary arteries (BIMA) may provide superior revascularisation with improved long-term survival and reduced need for repeat CABG. However, studies indicate that few patients having CABG in Europe and the USA actually receive BIMA because of concerns that it is technically more challenging and may increase early mortality and major morbidity.

The Arterial Revascularisation Trial (ART), one of the largest trials ever conducted in cardiac surgery, was a randomised trial of BIMA grafts versus SIMA grafts whose primary outcome was survival at 10 years. Secondary end-points included clinical events, quality of life and cost effectiveness. Results reported today at the ESC Congress are on safety data in the whole cohort up to one year after randomisation.

"We felt that a trial was necessary because fewer than 10% of patients in Europe - and fewer than 5% in the United States - currently receive two internal mammary arteries," said principal investigator David Taggart, Professor of Cardiovascular Surgery at the John Radcliffe Hospital, Oxford, UK, "mainly because of a perception that the use of bilateral artery grafts increases the early mortality and major morbidity of the operation."

The ART trial enrolled more than 3100 patients (mean age 64 years) in 28 hospitals in seven countries, who were randomised to receive SIMA or BIMA (both with supplementary venous grafts). According to Professor Taggart, results showed that the one year outcome "is a testament to the remarkable safety of coronary artery bypass grafting", with an overall mortality rate of 1.2% at 30 days (in each group) and 2.4% at one year. 

Results therefore showed that the use of two internal mammary arteries is indeed feasible in most patients and does not increase early mortality, stroke, myocardial infarction or duration of hospital stay. It did, however, lead to a small (1.3%) increase in the risk of sternal wound reconstruction.