Thirty-day vein remodeling is predictive of midterm graft patency after lower extremity bypass

Abstract

OBJECTIVES Successful adaptation of a vein graft to an arterial environment is incompletely understood. We sought to investigate whether early vein graft remodeling is predictive of subsequent patency. METHODS A prospective longitudinal study of 67 patients undergoing lower extremity bypass with autologous vein between February 2004 and April 2008. Preoperative blood samples were drawn for biomarkers. During the bypass operation, a 5 cm index segment of the graft was registered for serial lumen diameter measurements (0, 1, 3, 6, 9, and 12 months) using duplex ultrasound. Patients with at least 2 study ultrasounds were included in this analysis. RESULTS The median age was 70 years (IQR 59-76y) and the median follow-up was 32 months (IQR 15-47mo). Over half (55%) of the subjects were male, 40% had diabetes mellitus, 49% had critical limb ischemia, and most were on a statin (75%) and antiplatelet medication (91%). The median baseline high-sensitivity C-reactive protein level (hsCRP) for the cohort was 3.2mg/L (IQR 1.4-9.7mg/L). The average intraoperative, post-implantation vein lumen diameter was 3.9 ± 1.0mm, increasing to 4.7 ± 1.1mm at 1 month, an average 24 ± 27% change per subject. By 3 months, the average lumen diameter was 5.1 ± 1.6mm, with little subsequent change observed to 12 months. Non-white race, baseline hsCRP ≥5mg/L, statin use and initial lumen diameter were significantly associated with early (0-1 month) vein remodeling in a multivariable regression model. The primary patency rate for the cohort was 60 ±6.3% at 2 years. Initial lumen diameter of the index segment was not associated with primary patency, whereas larger lumen diameter achieved at 1 month (≥5.1mm) was positively associated with primary patency (P=.03, log-rank). Early (30 day) remodeling behavior was used to divide subjects into “poor remodelers” (< −5% lumen diameter change, N=6), “modest remodelers” (−5 to +25% change, N=29) and “robust remodelers” (>+25% change, N=30). Early remodeling category was significantly associated with primary patency rate at 2 years P=.02, log-rank). A multi-variable Cox proportional hazards model showed that modest (HR 3.9, 95% CI 1.02-15, P=.04) and poor (HR 13, 95% CI 1.9-89, P=.008) remodelers had significantly higher hazard ratios for graft failure than robust early remodelers. CONCLUSIONS Early remodeling of the arterialized vein appears to predict mid-term bypass graft patency. In addition to baseline diameter, race, inflammation, CRP, and statin use are associated with early adaptive remodeling, but the mechanism for these observations are not understood.

Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

“…Gasper et al demonstrated that early remodeling was predictive of late vein graft failure [25]. If translated to the clinical setting, our results suggest that external support is likely to increase long-term graft patency.…”

Vein graft failure

“…To test this hypothesis, we initiated a prospective cohort study to systematically determine remodeling characteristics of lower extremity bypass grafts over the first year of implantation. [20-23] Employing high-resolution ultrasound images, luminal and wall changes were characterized from a defined region of the vein graft. We also employed pulse wave velocity (PWV) analysis to determine stiffness changes in the vein over time.…”

“…[25, 26] Specifically, African American race was associated with less positive remodeling over the first month of implantation and vein grafts implanted in these patients never achieved the diameter of those in Caucasians. [23] Just as importantly diabetes mellitus, hypertension, and hyperlipidemia were not associated with remodeling; none of which have been shown to be associated with reduced patency of lower extremity vein grafts.…”

“…those demonstrating >25% change in lumen diameter, Figure 1. [23] To put this in perspective the use of small veins for bypass only has about a 2.5-fold increased risk of failure at one year[27] suggesting that the remodeling of the vein in the first 30 days is at least as important as vein implantation size.…”

Surgical Intervention for Peripheral Arterial Disease

“…In vein bypass grafts, an early adaptive remodeling occurs in response to increased shear stress and wall tension, resulting in overall vessel enlargement and increased wall thickness. 85,86 If the hyperplastic response continues, or is accompanied by a constrictive fibrosis, stenosis may ensue. Vein graft stenosis is most typically focal, for example, in the perianastomotic regions and at valve sites; more rarely it occurs diffusely throughout the graft.…”