Objectives – External stents have been shown to inhibit saphenous vein graft (SVG) intimal hyperplasia in animal studies and may therefore have the potential to do so after coronary artery bypass grafting (CABG). The goal of this study was to assess the clinical safety and efficacy of SVG external stenting for mitigation of diffuse intimal hyperplasia 1 year after CABG.
Methods –This three centre trial enrolled 30 patients with multi-vessel disease undergoing CABG. Each patient received one external stent device to a single SVG randomized to either the right or left coronary territories and one or more non-stented SVG served as the control(s). The primary endpoint was SVG intimal hyperplasia (mean area) assessed by intravascular ultrasound (IVUS) at 1 year. Secondary endpoints were SVG failure, the prevalence of SVG ectasia (>50% initial diameter) and overall SVG uniformity as judged by quantitative coronary angiography (QCA).
Results – Intra-operatively, all grafts had excellent flows measured by Transit Time Flowmetry. One-year follow up angiography was completed in 29 patients (96.6%). All patent SVGs (n= 53, 76.8%) were analyzed by QCA and IVUS data could be obtained for 43 SVGs. Both SVG mean intimal hyperplasia area and thickness were reduced between the stented and non-stented groups (4.37 ±1.40 versus 5.12 ±1.35 mm2,, P=0.04 and 0.37 ±0.1 versus 0.42 ±0.1 mm, P=0.06). In addition, the stented SVG group trended to demonstrate more uniform luminal caliber (P=0.08) and less SVG ectasia (6.7% versus 28.2%, P=0.05). Overall SVG failure rates did not differ significantly between the 2 groups (30% versus 28.2%, stented versus non-stented SVG, P=0.55). In particular the use of metallic clips rather than sutures to ligate SVG side branches appeared to increase the risk of graft occlusion and the severity of intimal hyperplasia.
Conclusions – External stenting reduces SVG diffuse intimal hyperplasia 1 year after CABG.
