(A) randomized comparison of No-Touch harvested upper versus leg saphenous veon as a secondary conduit for a coronary artery bypass grafting

Abstract

Background: Although total arterial revascularization is known to have the best long-term outcomes in coronary artery bypass grafting (CABG), saphenous vein grafts (SVGs) are most frequently used as a second conduit for CABG because they are convenient to harvest and plentiful. In an effort to improve the outcomes of using SVGs in CABG, we compared the histopathology and 1-year angiographic change of SVGs that were harvested from either the upper or the lower leg. Patients and methods: Patients aged 40-75 years old who were undergoing off-pump CABG for multi-vessel coronary artery disease were enrolled. A total of 26 patients were randomized into the following 2 groups: an upper leg vein (ULV) group (n=13) and a lower leg vein (LLV) group (n=13). All of the SVGs were harvested using the No-Touch technique, preserving perivascular tissue. Pressure dilatation was not applied. Before Y-anastomosis to the left internal thoracic artery, small segments of the proximal and distal ends of the SVG were obtained, and another segment, which had been exposed to internal thoracic arterial pressure before final anastomosis, was sampled (dilated). These three samples were histopathologically analyzed and subjected to hematoxylin and eosin, Kruppel-like factor (KLF)-4, serum response factor (SRF), and myocardin staining. Endothelial integrity, expression of vascular smooth muscle cell (VSMC), activation of related proteins and preservation of medial smooth muscle folding were measured, and luminal diameter/intimal and medial thickness were measured. Coronary angiography (CAG) was performed postoperatively and at 1 year after CABG. The SVG diameter and filling frame counts were measured by CAG to evaluate vascular remodeling. Results: No significant differences in endothelial integrity, expression of VSMC activation-related proteins and preservation of smooth muscle folding were observed between the ULV and LLV groups. The dilated sample, which was initially adjacent to the proximal sample, had a significantly larger luminal diameter in both groups (ULV group: dilated [1477±353 μm] vs proximal [858±266 μm], P<0.001

LLV group: dilated [1138±419 μm] vs proximal [623±143 μm], P=0.003). Additionally, the dilated samples had thinner intima than the proximal samples in both groups, as follows: the ULV group (dilated [132±124 μm] vs proximal [218±114 μm], P=0.036) and the LLV group (dilated [67±52 μm] vs proximal [175±61 μm], P<0.001). However, significant between-group differences did not exist. Twenty-four patients (92%) underwent a 1-year CAG, and it revealed that the diameter of SVGs decreased during the first year (negative remodeling) on average, as follows: ULV group (postoperative [4.6±0.8 mm] vs 1-year [3.5±1.6 mm], P=0.012) and LLV group (postoperative [4.1±0.8 mm] vs 1-year [2.5±1.1 mm], P=0.001). However, the decrease in the SVG diameter did not show a significant difference between groups (analysis of covariance, P=0.210). A total of 2 patients (8%) showed SVG occlusion at 1-year CAG: 1 of 12 (8%) in the ULV group and 1 of 12 (8%) in the LLV group (P>0.999). The SVG filling frame count decreased during the first year after CABG in both groups, without between-group differences (analysis of covariance, P=0.529). Conclusion: No clear evidence of superiority could be found with regard to the harvest site. ULV and LLV showed similar histopathology and angiographic changes during the first year. Further studies are needed to evaluate the long-term changes in SVGs as a secondary conduit in CABG.