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

Abstract

Objective: 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 was conducted of 67 patients undergoing lower extremity bypass with autogenous 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 at 0, 1, 3, 6, 9, and 12 months using duplex ultrasound imaging. The imaging substudy analysis included patients with at least two ultrasound assessments.

Results: Patients (55% male) were a median age of 70 years (interquartile range [IQR], 59-76 years), 40% had diabetes mellitus, 49% had critical limb ischemia, 75% were taking a statin, and 91% were taking an antiplatelet medication. Median follow-up was 32 months (IQR, 15-47 months). The median baseline high-sensitivity C-reactive protein level (hsCRP) was 3.2 mg/L (IQR, 1.4-9.7 mg/L). The average intraoperative, postimplantation vein lumen diameter was 3.9±1.0 mm, increasing to 4.7±1.1 mm at 1 month, an average 24%±27% change per patient. By 3 months, the average lumen diameter was 5.1±1.6 mm, with little subsequent change observed to 12 months. Nonwhite race, baseline hsCRP ≥5 mg/L, statin use, and initial lumen diameter were significantly associated with early (0- to 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 (≥5.1 mm) was positively associated with primary patency (log-rank, P=.03). Early (30-day) remodeling behavior was used to divide patients 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 (log-rank, P=.02). A multivariable Cox proportional hazards model showed that modest remodelers (hazard ratio, 3.9; 95% confidence interval, 1.02-15; P=.04) and poor remodelers (hazard ratio, 13; 95% confidence interval; P=.008) had significantly higher hazard ratios for graft failure than robust early remodelers.

Conclusions: Early remodeling of the arterialized vein appears to predict midterm bypass graft patency. In addition to baseline diameter, race, inflammation, hsCRP, and statin use are associated with early adaptive remodeling, but the mechanisms for these observations are not understood.

Figure 1

Changes in vein graft index segment lumen diameter from 0 to 12 months. The average percent change in lumen diameter was +24 ± 27% in the first postoperative month, dropping to approximately 0% change after 3 months.

Figure 2

Vein graft index segment lumen diameter is associated with race and hsCRP level. Values shown represent the mean diameter at each timepoint ±SEM. Over the 12 month study period, vein grafts of non-white subjects had significantly smaller lumen diameters (−.9 mm, 95% CI −1.5 to −.34 mm, P=.002; random-effects model) (A). Similarly, subjects with a baseline CRP ≥5mg/L had significantly smaller vein graft lumen diameters (−.5 mm, 95% CI −.98 to −.012 mm, P=.045; random-effects model) (B).

Figure 2

Vein graft index segment lumen diameter is associated with race and hsCRP level. Values shown represent the mean diameter at each timepoint ±SEM. Over the 12 month study period, vein grafts of non-white subjects had significantly smaller lumen diameters (−.9 mm, 95% CI −1.5 to −.34 mm, P=.002; random-effects model) (A). Similarly, subjects with a baseline CRP ≥5mg/L had significantly smaller vein graft lumen diameters (−.5 mm, 95% CI −.98 to −.012 mm, P=.045; random-effects model) (B).

Figure 3

Index segment lumen diameter based on eventual loss of primary patency. Values shown represent the mean diameter at each timepoint ±SEM. Although starting at a similar size as those that remained patent, vein grafts that eventually lost primary patency had a significantly smaller lumen diameter over time (−.5 mm, 95% CI −1.0 to −.052 mm, P=.03; random-effects model).

Figure 4

Early (0-1 month) remodeling is associated with primary patency, P=.02, log-rank.