AHA 2016: Similar mortality rates for CABG patients receiving single or bilateral internal thoracic artery grafts

After five years of follow-up, patients undergoing CABG who received single internal thoracic artery grafts had similar rates of mortality and cardiovascular events compared with those who received bilateral internal thoracic artery grafts, according to an interim analysis of an ongoing randomized trial.

The researchers also found that patients in the bilateral internal thoracic artery grafting group had more sternal wound complications.

Lead researcher David P. Taggart, MD, PhD, of the University of Oxford in the U.K., presented the results in a late-breaking clinical trials session at the American Heart Association Scientific Sessions in New Orleans.

The findings were simultaneously published in the New England Journal of Medicine on Nov. 14. 

“This study confirms that it’s at least safe to use bilateral [internal thoracic artery] grafts over the medium term,” Taggart said during a news conference.

More than one million CABG procedures are performed worldwide each year, according to Taggart. He added that previous trials showed CABG was highly effective in patients with multivessel and left main coronary artery disease.

The Arterial Revascularization Trial (ART) enrolled 3,102 patients at 28 cardiac surgical centers in seven countries from June 2004 through December 2007. The patients had multivessel coronary artery disease and were scheduled to undergo CABG.

The researchers randomly assigned the patients in 1:1 ratio to undergo single or bilateral internal thoracic artery grafting. They added that 2.4 percent of patients assigned to the single group crossed over and had bilateral internal thoracic artery grafting, while 14 percent of patients assigned to the bilateral group had single internal thoracic artery grafting.

The groups were well-balanced with regards to age, sex, race, body mass index and other patient characteristics. The mean age was approximately 63 years old, and 86 percent of the patients were males and 92 percent were white.

The groups also had similar rates of medications at five years: 88.9 percent received aspirin, 76.2 percent received beta-blockers, 89.0 percent received statins and 73.4 percent received ACE inhibitors or ARBs.

At five years of follow-up, 8.7 percent of patients in the bilateral graft group and 8.4 percent of patients in the single graft group had died. The results were similar when the researchers adjusted for age, sex, diabetes status and ejection fraction. Approximately half of the deaths were classified as cardiovascular in nature.

The composite of death from any cause, MI or stroke occurred in 12.2 percent of patients in the bilateral graft group and 12.7 percent of the single graft group. There were no significant differences between the groups with regards to the individual components, either.

There were also no significant differences in major bleeding, need for repeat revascularization, angina status and quality of life measures between the groups.

Sternal wound reconstruction occurred in 1.9 percent of patients in the bilateral graft group and 0.6 percent of the single graft group, which represented a statistically significant difference. Each of the patients had sternal wound reconstruction within the first year after surgery.

The researchers mentioned that the study was ongoing and would be complete in 2018 after 10 years of follow-up. Thus, this planned interim analysis did not provide definitive evidence comparing the two CABG approaches. They also noted that more patients assigned to the bilateral grafting group did not receive the procedure.