Does the use of bilateral internal mammary artery (IMA) grafts provide incremental benefit relative to the use of a single IMA graft? A meta-analysis approach

Objectives: Does the use of bilateral internal mammary artery (IMA) grafts provide incremental benefit relative to the use of a single IMA graft? Methods: Meta-analysis by qualitative and quantitative protocol of the studies published in the literature in the last 15 years. Only eight, out of 149 observational studies found, met our criteria: surgical results of bilateral versus single IMA, patient age range from 20 to 89 years, exclusion of emergency and diabetic patients, study group larger than 100 patients, minimal follow-up time. The final sample size included 16 362 patients. Results: Late survival was evaluated at 5 and 10 years. The hazard ratio (HR) was calculated from seven studies, the difference of survival was from six and five studies, respectively. The effect size was summarized using a random effect model, suggested by the results of statistical test for homogeneity of the HR (P < 0.05) and of the survival difference at 5 (P < 0.05) and at 10 years (P < 0.05). The bilateral IMA estimate of combined HR was 0.79 (95% confidence limits, C.L. = 0.66 divided by 0.91). The combined difference of survival probability at 5 years was 0.014 (95% C.L. = -0.03 divided by 0.06) and at 10 years was 0.07 (95% C.L. = 0.003 divided by 0.170). Conclusion: There is significant evidence in favor of decreasing death risk of bilateral versus single IMA procedure. (C) 2002 Elsevier Science B.V. All rights reserved.