Introduction:
Saphenous vein grafts (SVGs) have high rates of both early (≤ 1 year) and late failure following coronary arterial bypass graft surgery (CABG).
Hypothesis:
Endothelial shear stress (ESS) is a critical determinant of the natural history of coronary atherosclerosis, but the influence on the structural changes of SVGs has not been studied. We evaluated the effect of ESS on the serial anatomic outcomes of SVGs assessed by optical coherence tomography (OCT) during the first postoperative year.
Methods:
We performed 3-dimensional SVG reconstruction in 8 SVGs using fusion of angiographic and OCT data 5-7 days after surgery (baseline) and at 12-month follow-up. Baseline ESS was assessed using computational fluid dynamics. The reconstructed SVGs were divided in consecutive 3-mm segments (n=181), and we assessed the association of baseline ESS with the anatomic outcomes in the corresponding segments at follow-up: change in lumen area and plaque burden, and neointimal area at follow-up. Baseline ESS was categorized according to the tertiles of the ESS frequency distribution.
Results:
Median baseline ESS in SVGs was 0.48 Pa [IQR: 0.37-0.61 Pa]). Baseline low ESS was associated with: (i) the largest decrease in lumen area (low ESS category: -8.72±0.95 mm2 vs. moderate ESS category: -5.67±0.95 mm2 vs. high ESS category: -3.64±0.95 mm2; p<0.001 low vs moderate and high ESS category), (ii) the largest increase in plaque burden (low ESS category: 24.3±3.4% vs. moderate ESS category: 22.6±3.4% vs. high ESS category: 20.9±3.4%; p=0.011 low vs high ESS category), and (iii) the largest neointimal area at 12 months (low ESS category: 4.02±0.45 mm2 vs. moderate ESS category: 3.65±0.45 mm2 vs. high ESS category: -3.57±0.45 mm2; p=0.020 low vs moderate ESS category, and p=0.009 low vs high ESS category).
Conclusions:
SVG areas with the lowest local ESS develop the largest lumen constriction, plaque burden increase and neointima formation. These findings provide important insights into the pathogenesis of early SVG failure.
Editorial: Non-pharmacologic Sustained Endothelial Shear Stress: An Evolving Clinical Paradigm
