Bilateral internal thoracic artery grafting is not associated with survival benefit in patients with ischemic cardiomyopathy undergoing surgical revascularization

S. K. Singh¹, A. Vinogradsky², M. Kirschner², Y. Hohri³, C. Wang⁴, P. Kurlansky⁵, K. Takeda^2
1Columbia University, New York, New York ²Columbia University Medical Center, New York, New York ³Columbia University, Kyoto, New York ⁴Columbia University Vagelos College of Physicians and Surgeons, New York, New York ⁵Columbia University Irving Medical Center, New York, New York

Purpose: The benefit of bilateral internal thoracic artery (BITA) grafting in patients with ischemic cardiomyopathy requiring coronary artery bypass grafting (CABG) remains unknown. We sought to assess the impact of BITA grafting on long-term survival in this population.

Methods: Patients with reduced ejection fraction (EF < 35%) who underwent CABG at our institution from 2015-2021 were identified. Baseline characteristics, operative details including use of BITA or single internal thoracic artery (SITA), as well as post-operative outcomes and long-term survival were collected. Cox-proportion regression hazard model was used to study the association of BITA grafting with long-term survival when controlling for confounders. To explore the EF-dependent effect of BITA grafting on mortality, the hazard model was fit to the entire population with an interaction term for preoperative EF, modeled as a natural spline.

Results: A total of 377 patients with reduced EF underwent CABG with either BITA (n = 107) or SITA (n = 270). BITA recipients were more often male (84.1% vs 74.1%, p = .04) and SITA recipients tended to have higher incidences of diabetes (65.9% vs 56.1%, p = 0.07) and congestive heart failure (39.1% vs 22.4%, p = 0.06). BITA recipients had a similar incidence of preoperative mechanical circulatory support use compared to SITA patients (9.3% vs 10.7%, p = 0.69) and there were no differences in baseline EF (25% vs 22%, p = 0.13) or LVEDD (54 vs 55mm, p = 0.49). Operative mortality was similar between BITA and SITA groups (2.8% vs 3.7%, p = 0.67). Long-term survival was similar between BITA and SITA patients (HR 0.68, 95%CI 0.35-1.31, p = 0.25) after controlling for age, gender, peripheral arterial disease, preoperative dialysis, LVEDD and EF (Table 1). When EF was examined as a continuous variable, there was no clear association between EF and a survival benefit of BITA grafting after controlling for confounders.

Conclusion: In our study, BITA grafting was not associated with a long-term survival benefit in patients with reduced ejection fraction undergoing CABG. Further studies are required to determine which sub-populations may benefit from BITA grafting.

Identify the source of the funding for this research project: None