Antiatherosclerotic Phenotype of Perivascular Adipose Tissue Surrounding the Saphenous Vein in Coronary Artery Bypass Grafting

Abstract

Background Perivascular adipose tissue (PVAT) is associated with metabolically driven chronic inflammation called metaflammation, which contributes to vascular function and the pathogenesis of vascular disease. The saphenous vein (SV) is commonly used as an essential conduit in coronary artery bypass grafting, but the long‐term patency of SV grafts is a crucial issue. The use of the novel “no‐touch” technique of SV harvesting together with its surrounding tissue has been reported to result in good long‑term graft patency of SV grafts. Herein, we investigated whether PVAT surrounding the SV (SV‐PVAT) has distinct phenotypes compared with other PVATs of vessels. Methods and Results Fat pads were sampled from 48 patients (male/female, 32/16; age, 72±8 years) with coronary artery disease who underwent elective coronary artery bypass grafting. Adipocyte size in SV‐PVAT was significantly larger than the sizes in PVATs surrounding the internal thoracic artery, coronary artery, and aorta. SV‐PVAT and PVAT surrounding the internal thoracic artery had smaller extents of fibrosis, decreased gene expression levels of fibrosis‐related markers, and less metaflammation, as indicated by a significantly smaller extent of cluster of differentiation 11c–positive M1 macrophage infiltration, higher gene expression level of adiponectin, and lower gene expression levels of inflammatory cytokines, than did PVATs surrounding the coronary artery and aorta. Expression patterns of adipocyte developmental and pattern‐forming genes were totally different among the PVATs of the vessels. Conclusions The phenotype of SV‐PVAT, which may result from inherent differences in adipocytes, is closer to that of PVAT surrounding the internal thoracic artery than that of PVAT surrounding the coronary artery or that of PVAT surrounding the aorta. SV‐PVAT has less metaflammation and consecutive adipose tissue remodeling, which may contribute to high long‐term patency of grafting when the no‐touch technique of SV harvesting is used.

Macrophage Polarization in the Perivascular Fat Was Associated With Coronary Atherosclerosis

“… 5 , 6 In humans, macrophage infiltration in the coronary PvAT was associated with CAD (coronary artery disease). 7 , 8 , 9 , 10 , 11 , 12 , 13 The inflammation mediated by polarized macrophages in the coronary PvAT was higher in patients with CAD in comparison with other areas (eg, aorta, internal thoracic artery, and saphenous vein). 12 , 14 However, these studies did not evaluate plaque composition or plaque instability.…”

Saphenous vein harvesting: Meta‐analysis, metaflammation, and adipose tissue remodeling

“…5 In addition, we recently showed that PVAT surrounding the SV and ITA had lower levels of metaflammation and consecutive adipose tissue remodeling, specifically augmented immune cell infiltration, induction of proinflammatory cytokines, and increased fibrosis, than did PVAT surrounding the coronary artery and PVAT surrounding the aorta. 6 These findings suggest that the phenotype of PVAT surrounding the SV is linked to a high rate of long-term patency of grafts in CABG using NT-harvested SV grafts.…”

Reply to saphenous vein harvesting: Meta‐analysis, metaflammation, and adipose tissue remodeling

“…In their recent letter to the editor, Furuhashi et al discuss the role of perivascular adipose tissue (PVAT) in the progression of or protection from atherosclerotic disease in coronary bypass conduits. [1][2][3][4] They make the valid point that when comparing patency rates between arterial and venous grafts, one is in part comparing the effects of PVAT preservation (arterial grafts) versus removal (venous grafts).…”

“…9,10 The current evidence regarding the role of PVAT is only preliminary. [2][3][4] The NTSV may have a future role to play, either in combination with or instead of currently recommended conduits, but…”

“…Formal guidelines render the use of the RA a class I indication, and further define the degree of stenoses for which it should be used (>70% on the lateral territory and >90% on the inferior territory) 9,10 . The current evidence regarding the role of PVAT is only preliminary 2–4 . The NTSV may have a future role to play, either in combination with or instead of currently recommended conduits, but additional data are needed.…”