Effect of Bilateral Internal Mammary Artery on Long-Term Survival: A Meta-Analysis Approach

Study Questions:

What is the long-term (up to 10 years) survival benefit of bilateral internal mammary artery (BIMA) grafting, compared to single internal mammary artery (SIMA) grafting, following coronary artery bypass surgery (CABG)?


Studies that compared survival between SIMA and BIMA patients with follow-up of more than a mean of 9 years were included in this meta-analysis.


Nine studies (n = 15,583) were included in the meta-analysis, none of which were randomized trials. None included a description of unbiased treatment assignment. No study demonstrated a significantly deleterious effect of BIMA. There was a significant reduction in mortality through the use of BIMA compared to SIMA (hazard ratio, 0.79; 95% confidence interval, 0.75-0.84).


The authors concluded that BIMA appears to have better survival, compared to SIMA, up to 10 years following CABG.


This is an important study, which corroborates previous observations that the survival benefit of BIMA grafting extends to the longer-term. Although evidence would suggest the benefits of BIMA grafting, the use of this technique during CABG in contemporary practice has been low (fewer than 10% of European and fewer than 5% of North American patients receive BIMA grafts). While BIMA grafting may be avoided by surgeons because of the potentially higher risk of sternal infection or dehiscence and other complications, the current analysis would suggest benefits of a more liberal use of BIMA grafting. Although randomized trial data would provide better clarity to inform the decision between BIMA and SIMA, 10-year survival results from the ART (Arterial Revascularization Trial) study will not be reported until 2018.

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