Which Is Better? Pedicled versus Skeletonized Internal Mammary Artery Grafts in Coronary Artery Bypass Grafting: Emphasis on the Antispastic Role of Perivascular Adipose

Background: The internal mammary artery (IMA) is the conduit of choice for coronary artery bypass grafting (CABG). While it can be harvested as a pedicled (with surrounding tissue) or skeletonized (stripped bare) graft, the optimal technique remains debated. The perivascular adipose tissue (PVAT) surrounding the IMA is no longer considered inert but is a bioactive organ secreting vasoactive adipokines. This review synthesizes the evidence on the role of PVAT in IMA vasoreactivity and its implications for the choice of harvesting technique. Methods: A systematic literature search was conducted in PubMed/MEDLINE, Embase, and CENTRAL up to 1 December 2025 for original studies investigating PVAT function in human IMA or comparing pedicled vs. skeletonized harvesting with relevant vasomotor or clinical outcomes. Data were extracted and synthesized narratively. Results: The included studies consistently demonstrate that IMA-PVAT exerts a potent anticontractile and vasorelaxant effect. This is mediated through multiple pathways, including the release of adiponectin, which enhances endothelial nitric oxide synthase function, and the production of non-nitric oxide, non-prostanoid relaxing factors that act directly on vascular smooth muscle. Ex vivo studies show conflicting results that skeletonization, by removing PVAT, may or may not augment vasoconstrictive responses and increase susceptibility to spasm but preservation of PVAT definitively preserves vasorelaxation properties of IMA. Though less definitive and conflicting, clinical studies, particularly a recent large post-hoc RCT analysis, suggest that harvesting of the IMA during CABG surgery using a skeletonized technique was associated with a higher rate of graft occlusion and worse clinical outcomes than the traditional pedicled technique. Conclusions: PVAT is an integral, protective component of the human IMA, providing a multimodal defense against vasospasm. The pedicled harvesting technique, by conserving PVAT, leverages these inherent vasorelaxant properties and is physiologically superior for minimizing graft spasm. Surgical strategy should consider the antispastic benefit of the pedicled IMA, balanced against the potential sternal wound healing and length advantages of skeletonization in high-risk patients.