A systematic review and meta-analysis of in situ versus composite bilateral internal thoracic artery grafting.

OBJECTIVES: This meta-analysis examines whether there is any advantage of coronary artery bypass graft with bilateral internal thoracic artery (BITA) as an in situ versus composite graft. METHODS: We searched MEDLINE and EMBASE Databases from 1996 to 2016 for studies that compared coronary artery bypass graft with BITA as in situ versus composite graft. Data were extracted by 2 independent investigators and meta-analyzed with the use of random effects. RESULTS: Two randomized controlled trials (RCTs; n = 705), 2 matched (n = 1688), and 4 unadjusted observational studies (n = 3517) met inclusion criteria. Composite grafting trended towards greater distal anastomoses (+0.22, 95% confidence interval, -0.01 to +0.45 anastomoses/patient; P = .06 [4 unadjusted observational studies]) and greater distal anastomoses using an internal thoracic artery (+0.80, 95% confidence interval, 0.41-1.18 anastomoses/patient; P < .001 [1 RCT]). There were no differences in perioperative or longer-term composite cardiovascular outcomes comparing in situ versus composite BITA or individual outcomes of mortality, repeat revascularization, myocardial infarction, and cardiovascular mortality. Pooled results differed by study type with pooled results from lower-risk-of-bias RCTs typically showing increases in events rates, and pooled results from higher-risk-of-bias unadjusted observational studies typically showing decreases in event rates of in situ versus composite BITA. Post hoc subgroup analysis suggested possible improvements in all-cause mortality and revascularization for in situ BITA in studies with short-term (<5 years) versus longer-term follow-up, regardless of study type. CONCLUSIONS: Our meta-analysis found that use of BITA as a composite graft configuration facilitated greater internal thoracic artery revascularization but both grafting strategies offer similar clinical outcomes. Our study supports the use of in situ and composite BITA for select patients but high-quality, long-term prospective trials are needed.