External support device for SVG grafts in CABG surgery shows promise

No significant difference in intimal hyperplasia was reported between supported and unsupported saphenous vein grafts (SVGs) in patients who underwent coronary artery bypass graft (CABG) surgery in the VEST trial. However, the additional sensitivity analysis did show benefits of the externally supported SVG. Further investigation of external graft support devices is warranted.

Prof. John Puskas (Mount Sinai Hospital, Israel) explained that 50% of all SVGs fail within 10 years, mostly due to proliferative intimal hyperplasia of the grafts [1]. This process causes graft atherosclerosis and occlusion, leading to unwanted clinical events. According to Prof. Puskas, external support of SVGs may prevent SVG dilatation and reduce intimal hyperplasia. In addition, an external support device could improve long-term vein patency by reducing SVG wall tension, decreasing lumen irregularities, and improving haemodynamics and shear stress.

The current VEST Pivotal trial (NCT03209609) assessed the efficacy and safety of an external support device for SVGs in reducing intimal hyperplasia. The randomised, within-patient-controlled study design included 224 patients with multi-vessel coronary artery disease who were scheduled for CABG surgery. One SVG bypass was randomised to be externally supported, whereas another served as control. The primary endpoint was intimal hyperplasia at 1-year follow-up, evaluated by intravascular ultrasound (IVUS).

No statistical difference was observed between the area of intimal hyperplasia in mm^{^2} of supported (5.11) and unsupported SVGs (5.79; P=0.072). However, the primary analysis was performed with imputation of missing data. An additional sensitivity analysis that was executed on patients who had IVUS of both grafts (n=113) showed a significant reducing effect of the supported graft on the area of intimal hyperplasia (4.58 vs 5.12; P=0.043). In 59.5% of the supported grafts, there were no reported irregularities in lumen diameter compared with 53.5% in the unsupported grafts. The safety analysis did not reveal worrisome safety signals of the external support device after 12 months.

Prof. Puskas mentioned that the rate of compromised vessels was higher than expected. This had an impact on the primary analysis. Since the PREVENT IV trial (NCT00042081) showed similar vein graft failure rates, this could have been foreseen, admitted Prof. Puskas. He explained that arterial grafts are qualitatively better and more durable than vein grafts and that the ‘no-touch’ technique of saphenous vein preparation for CABG could increase graft patency. However, this procedure was not performed in the current study. “Future studies should investigate the long-term value of external support devices for vein grafts and develop novel tools and measures to prevent early vein graft failure,” concluded Prof. Puskas.

 

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   1. Puskas JD, et al. Efficacy and Safety of an External Support Device for Saphenous Vein Coronary Bypass Graft: The VEST Trial. LBS01, AHA Scientific Sessions 2021, 13–15 November.

 

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Posted on 14 January 202231 January 2024