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Early Remodeling Of Lower Extremity Vein Grafts: Modulation Of Hemodynamic Adaptation By Systemic Inflammation

Christopher D. Owens, Nicole Wake, Andres Schanzer, Cristos Ifantides, Frank J. Rybicki, Amanda G. Whitmore, Dimitrios Mitsouras, Marie D. Gerhard-Herman, Michael Belkin, Mark A. Creager, Michael S. Conte ∙ Brigham & Women's Hospital, Boston, MA

Objective: The remodeling of vein grafts following arterialization is incompletely understood. We sought to examine the hypothesis that systemic inflammation influences the early adaptation of lower extremity vein bypass grafts. Methods: Prospective observational study of patients (N=147) undergoing lower extremity bypass using autogenous vein. A baseline plasma sample was obtained on the morning of surgery for high-sensitivity C-reactive protein (hsCRP) assay. In an imaging substudy, patients underwent serial ultrasound (US @ 0, 1 month; N=86 pts) and 2D high-resolution (390 micron in-plane, 4 mm slice thickness) magnetic resonance (MRI @ 1 month; N=30 pts) imaging of a defined segment of the graft. Ultrasound pulse wave velocity measurements were used to assess changes in graft stiffness. Results: Among the overall cohort, patients with an elevated baseline hsCRP (≥5 mg/L) experienced an increased incidence of graft-related events over a mean follow-up period of 16.7 months (p=.036, log-rank-test). US data demonstrated that lumen diameter changes from 0-1 month (27% mean diameter increase) were correlated with initial shear stress (Table). Despite similar initial vein diameter and shear stress values, grafts in the elevated hsCRP group demonstrated significantly less positive remodeling from 0-1 month (13.5% vs 40.9%, p=.007). By regression analysis, hsCRP was inversely correlated with 0-1 month lumen diameter change (r=.37, p=.018). Early positive remodeling was also greater among patients on statins (30% vs 11%, p=.02). Graft wall thickness at one month, as assessed by T2-weighted MRI, was not different between hsCRP risk groups (0.75 vs 0.72 mm, p=NS). Grafts in the high hsCRP group tended to be stiffer at one month, as reflected by a higher calculated elastic modulus (E=50.4 vs 25.1 Mdynes/cm2, p=.07). Conclusions: Early positive remodeling of vein grafts is a shear-dependent response that is significantly modulated by systemic inflammation. In contrast, wall thickness at one month does not appear to be correlated with hsCRP, although material properties (E) of the wall appear divergent. These findings suggest that the relationship between baseline hsCRP and clinical graft events may be related to alterations in the early outward remodeling response.