Bilateral Versus Single Internal Mammary Artery Grafting in the Elderly: Long-Term Survival Benefit

Background: Extensive evidence documents a survival benefit for bilateral internal mammary artery (BIMA) grafting compared with single internal mammary artery (SIMA) grafting for patients with advanced coronary artery disease. However, controversy continues to exist regarding the incremental benefit of broadly applied BIMA grafting in elderly patients.

Methods: Retrospective analysis was conducted of 4,503 consecutive isolated coronary artery bypass grafting operations (SIMA, n = 2,340 and BIMA, n = 2,163) performed from 1972 to 1994. Multivariate analysis was used to created propensity score-matched groups of SIMA (n = 1,063) and BIMA (n = 1,063) to compare patients 65 years of age and older, and 70 years of age and older (n = 612), with similar baseline characteristics. Survival status was obtained by periodic follow-up, query of the US National Death Index, and other Internet searches, and was 99.6% complete.

Results: The propensity score-matched groups experienced similar perioperative mortality and morbidity. Survival benefits were found for BIMA versus SIMA grafting across both age categories. Actuarial curves after 23,593 patient-years of follow-up (mean BIMA = 11.7 years; 6 weeks to 33.1 years; mean SIMA = 10.5 years; 6 weeks to 30.7 years) demonstrated improved long-term survival for BIMA versus SIMA patients at 12 years (51.0 ± 1.5% versus 39.0 ± 1.5%) and at 24 years (3.5 ± 0.7% versus 4.5 ± 0.7%; p < 0.001). Similarly, in matched groups of patients age 70 and older, overall survival was also enhanced with BIMA grafting (p = 0.005).

Conclusions: Advanced age should not be a contraindication for BIMA grafting. Long-term follow-up clearly demonstrates that BIMA grafting when broadly applied in elderly patients results in improved long-term survival over SIMA grafting.