ART: Early results for bilateral IMA in CABG offer some promises, some concerns

One-year data from what the lead investigator characterized as one of the largest-ever randomized clinical trials of two CABG surgery techniques has found no differences in major clinical events between patients treated with either single internal mammary artery (SIMA) grafts or bilateral internal mammary arteries (BIMA).

Presenting the results here at the European Society of Cardiology 2010 Congress, Dr David Taggart (University of Oxford, UK) emphasized that the primary end point of the study is 10-year survival, so results for the overall trial won't be available until 2015 at the earliest. But 30-day and one-year results, presented today, provide reassurances that BIMA during CABG is feasible. Of note, however, BIMA grafts were associated with a small but statistically significant increase in need for sternal-wound reconstruction.

After studies during the 1980s first reported that internal mammary arteries rather than saphenous vein grafts improved survival and freedom from angina, MI, and repeat interventions, a number of groups proposed that using not one but bilateral internal mammary arteries could improve outcomes even further. While BIMA has now been used at some centers for almost 10 years, no randomized clinical trial has ever proven its equivalence or superiority, and naysayers have feared that the more technically demanding operation would increase surgery and recovery times, increase risk of infection due to delayed wound healing, and potentially lead to reduced survival.

As Taggart reported today, the Arterial Revascularisation Trial (ART) randomized 3102 patients at 28 hospitals in seven countries to SIMA (n=1554) or BIMA (n=1548). In-hospital, length of surgery, ventilation time, and hospital recovery times were indeed increased in the BIMA group, but none to a statistically significant degree. At 30 days and one year, there were no differences in rates of all-cause mortality, cardiac mortality, stroke, MI, or repeat revascularization procedures. The only differences seen were in rates of sternal wound reconstruction: 1.3% in the SIMA group and 1.9% in the BIMA group.

Other results are also important, said Taggart, pointing to the low overall mortality at 30 days and one year, which was 1.2% and approximately 2.4% in both groups. Rates of stroke, MI, and repeat revascularizations were all less than 2% at 12 months, with similar rates in the two groups. This is "testament to the safety of contemporary CABG grafting with one or two internal mammary arteries," Taggart concluded.