Is internal mammary artery graft beneficial in emergent coronary artery bypass surgery? A Society of Thoracic Surgeons national database analysis.

Background: Often, only saphenous vein grafts (SVGs) are used in emergent coronary artery bypass graft (CABG) procedures to provide quicker myocardial revascularization despite its lower long-term patency relative to the internal mammary artery (IMA) grafts. We examined differences between IMA and non-IMA graft recipients in emergent CABGs and its impact on in-hospital outcomes.

Methods: Retrospective review of Society of Thoracic Surgeon National Database was done to identify patients age ≥18 years undergoing primary emergent isolated CABG between 2013 and 2016. Emergent salvage, non-LAD disease, subclavian stenosis and revascularization with other arterial grafts were excluded. The study population was divided in two groups: IMA and non-IMA groups. Demographics, preoperative, intraoperative factors and postoperative outcomes were analyzed between the groups.

Results: Of 18,280 emergent CABGs during the study period, 16281 had IMA used and 1999 had only vein grafts. The IMA group was younger, more likely to be male, had lower creatinine and higher ejection fraction. The non-IMA and IMA groups were then propensity risk matched with ratio of 1:2 which showed significantly higher in-hospital mortality in the non-IMA group (15% vs. 7%, P<0.0001). The non-IMA groups also had higher rates bleeding (5% vs. 3%, P<0.01), renal failure (10% vs.6%, P<0.0001) and prolonged vent (44% vs. 30%, P<0.0001).

Conclusions: IMA grafts in primary isolated emergent CABGs are associated with significantly lower rates of in-hospital mortality. Even for emergent CABG there may be a clinical benefit in using IMA grafts rather than SVGs only.