Vein graft support device does not improve intimal hyperplasia area after CABG
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Use of an external saphenous vein graft support device did not improve intimal hyperplasia area in patients undergoing CABG compared with an unsupported graft, according to results from the VEST trial.
According to research presented at the American Heart Association Scientific Sessions, although researchers found no safety signals with regard to the external vein graft support device (Vascular Graft Solutions), they observed a higher-than-expected rate of occlusion and/or diseased vessel in both groups.
“Proliferative intimal hyperplasia of the saphenous vein grafts after coronary bypass surgery predisposes to the later development of graft atherosclerosis and subsequent occlusion,” John D. Puskas, MD, site chair of cardiovascular surgery at Mount Sinai St. Luke's, said during a presentation. “Indeed, 50% of all vein grafts may be closed 10 years after coronary bypass surgery. An external support of saphenous vein graphs has a theoretical potential to prevent saphenous vein graft dilation, the initiator of that intimal hyperplasia, and thereby slow the rate of intimal hyperplasia and increase long-term vein graft patency by reducing vein graft wall tension, reducing lumen irregularities preventing and improving hemodynamic and sheer force stresses within the graft.”
To evaluate the efficacy and safety of the external support device for saphenous vein grafts used in CABG, researchers initiated the VEST randomized controlled trial, enrolling 224 patients with multivessel CAD scheduled to undergo on-pump CABG with two or more grafts (mean age, 66 years; 21% women; 92% white; 50.9% with diabetes; mean left ventricular ejection fraction, 54.4%).
Within an individual patient, clinicians would add graft support to one saphenous vein but not to a second one, so each patient had one supported graft and one control graft.
According to the presentation, the device was a braid of 42 cobalt chromium wires, available in 16 dimensional models and would fit outside and over the saphenous vein graft used for CABG.
The primary efficacy endpoint was intimal hyperplasia area as assessed by IVUS at 1 year post-CABG. Secondary efficacy endpoints included 1-year lumen diameter uniformity assessed by cardiac angiography and graft failure, defined as 50% or more stenosis as assessed by cardiac angiography. The main safety endpoint was major adverse cardiac and cerebrovascular events, defined as death, MI, stroke or ischemic-driven target vessel revascularization of the supported graft or associated target coronary artery at 1 year.
Twenty-one patients were excluded due to death, loss to follow-up or refusal to undergo IV ultrasound. Of the remaining grafts, 55 with external support were occluded or severely diseased and five experienced technical issues with IV ultrasound. A total of 56 grafts without external support were occluded or were severely diseased and five experienced technical issues with IV ultrasound.
In the final analysis, a total of 113 patients completed IVUS of both grafts at 1 year.
At 1 year, approximately 42% of participants had at least one occluded and/or diseased vein graft.
The primary endpoint of difference in intimal hyperplasia between supported and unsupported saphenous vein grafts did not meet statistical significance while accounting for all 203 patients included in the main analysis, including those with occluded and severely diseased grafts (Primary analysis with imputation: supported, 5.11 mm2; unsupported, 5.79 mm2; P = .072), according to the researchers.
In a sensitivity analysis of the 113 patients who had IVIUS on both grafts, the primary endpoint favored the supported group (4.58 vs. 5.12 mm2; P = .043).
According to the presentation, 1-year lumen diameter uniformity was not put to statistical comparison, but researchers identified no intimal irregularity in 59.5% of supported grafts and in 53.5% of unsupported grafts.
For the secondary endpoint of graft failure, stenosis of 50% or more was observed in 30.2% of supported grafts and 26.2% of unsupported grafts.
At 1 year, the composite safety endpoint of major adverse cardiac and cerebrovascular events occurred in 7.1% of patients, with mortality occurring in 2.2% of the cohort; stroke in 2.7%; MI in 3.1%; and ischemic-driven target vessel revascularization of supported graft or associated target coronary artery in 1.3%. The rate of revascularizations of nonsupported grafts or nonischemic territories was 4.5%.
“In this prospective randomized study of the efficacy and safety of an external support device for vein graphs used in [CABG], the difference in intimal hyperplasia between supported and unsupported vein graphs did not reach statistical significance when accounted for in a primary analysis that included imputed data for missing values of intimal hyperplasia,” Puskas said during the presentation. “This may relate to the higher-than-expected incidents of occluded and diseased vein grafts preventing intravascular ultrasound.
“It's important to note that in the sensitivity analysis of patients who did have IV ultrasound of both vein graphs, we did see a lower area of intimal hyperplasia,” Puskas said. “Importantly, there were no safety signals observed in the study, and we feel that further investigation of external graft support devices is warranted to improve long-term graft patency and clinical outcomes.”
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Puskas JD, et al. LBS.01. Valves, Veins and New Viewpoints in Cardiothoracic Surgery. Presented at: American Heart Association Scientific Sessions; Nov. 13-15, 2021 (virtual meeting).
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