"Outcomes after Bilateral vs. Single Internal Thoracic Artery Grafting in Coronary-Artery Bypass Surgery".The New England Journal of Medicine. 2016.

Clinical Question

Does the use of bilateral internal thoracic artery grafting improve long-term outcomes compared with the use of a single internal thoracic artery plus vein grafts in patients undergoing coronary-artery bypass grafting (CABG)?

Bottom Line

At 5 years of follow-up, there was no significant difference between the use of single and bilateral internal thoracic artery grafts concerning mortality or rates of cardiovascular events. There was an increase in sternal wound complications with bilateral grafting.

Major Points

Guidelines

Existing guidelines prior to and up to the publication of this study do not specifically recommend bilateral over single arterial grafting in CABG, though it is understood that arterial grafts have better long-term patency than veins.

Design

- Multicenter, randomized trial
- N=3,102 patients scheduled for CABG
- Bilateral internal thoracic artery grafting (n=1,548)
- Single internal thoracic artery grafting (n=1,554)
- Setting: 28 cardiac surgery centers in 7 countries
- Enrollment: 2004-2007
- Follow-up: 5 years
- Analysis: Intention-to-treat

Population

Inclusion Criteria: Patients with multivessel coronary artery disease who were scheduled to undergo CABG, excluding those requiring only single grafts or concurrent valve surgery, or with a history of CABG.
Exclusion Criteria: As stated in inclusion criteria.

Interventions

Patients were randomly assigned to undergo single or bilateral internal thoracic artery grafting. Surgical management was based on local practice, with the internal thoracic artery grafts used for the two most important coronary arteries on the left side. Additional grafting was completed with vein or radial-artery grafts as necessary.

Outcomes

Primary Outcome: Death from any cause at 10 years (ongoing).
Secondary Outcomes: Composite of death from any cause, myocardial infarction, or stroke by 5 years.
At 5 years:
- Death rate: 8.7% in bilateral-graft group vs. 8.4% in single-graft group (HR 1.04; P=0.77)
- Composite outcome: 12.2% in bilateral-graft group vs. 12.7% in single-graft group (HR 0.96; P=0.69)
- Sternal wound complications: 3.5% in bilateral-graft group vs. 1.9% in single-graft group (P=0.005)

Criticisms

The study does not yet offer long-term results, which are crucial for evaluating the efficacy of bilateral vs. single internal thoracic artery grafting in CABG, particularly given the expectation that differences in outcomes might emerge after a longer duration.

Funding

Funded by the British Heart Foundation, the U.K. Medical Research Council, and the National Institute of Health Research Efficacy and Mechanism Evaluation Programme.

Further Reading