Comparison of the vascular responses to balloon-expandable stenting in the coronary and peripheral circulations: Long-term results in an animal model using the TriMaxx stent

ObjectiveThe clinical results after stenting in the coronary and peripheral circulations are vastly different. Possible explanations for this discrepancy include generally longer and more complex lesions in the periphery, variable vascular responses to injury according to anatomic location, disparate blood flow rates, and impedance in coronary vs skeletal smooth muscle beds, or phenotypic differences in neointimal hyperplasia and remodeling. This study examined the long-term results (6 months) after implantation of phosphorylcholine-coated balloon-expandable stents in a porcine model of experimental in-stent coronary and peripheral arterial restenosis.MethodsForty-eight stainless steel-tantalum-stainless steel composite balloon-expandable stents coated with phosphorylcholine (TriMaxx stent, Abbott Laboratories, Abbott Park, Ill) were implanted in the coronary (3.0 × 15 mm) or larger femoral arteries (4.0 × 38 mm) of Yorkshire crossbred swine to achieve a 1.1:1 stent-to-artery ratio. After 28, 90, or 180 days, the arteries were excised, perfusion-fixed at 100 mm Hg, sectioned, and stained with hematoxylin and eosin for morphometric evaluation.ResultsOne animal did not survive to euthanasia; all arteries in surviving animals were patent. No significant differences were found in mean injury or inflammation scores among the groups or time points. The larger femoral arteries generated more neointimal area over time than the coronary arteries. The neointimal area in coronary arteries was 2.76 ± 0.71, 1.75 ± 0.42, and 1.83 ± 0.19 mm2 at 28, 90, and 180 days, respectively, and 5.20 ± 0.97, 3.11 ± 0.53, and 5.10 ± 0.80 mm2 in the femoral arteries (P < .05 coronary vs femoral at 180 days). This led to statistically significantly increased percent area stenosis at 180 days (coronary 27% ± 4% vs femoral 45% ± 5%; P < .05).ConclusionsThe vascular response to balloon-expandable stenting in the coronary and peripheral circulations is different. After 6 months, neointimal hyperplasia and stent-induced stenosis were increased in peripheral porcine arteries compared with coronary arteries.

Clinical RelevanceAtherosclerotic vascular disease and its sequelae remain the single greatest killers in the world. Significant advances have been made in the development of endovascular techniques for both coronary and peripheral interventions. Although endovascular intervention is highly effective in the coronary and iliac arterial system, it has been shown to be less effective in the infrainguinal circulation. In this study, we tested the hypothesis that the post-stenting neointimal and remodeling responses of normal porcine peripheral arteries was different than that of the coronary arteries receiving identical stents and that inherently less favorable remodeling in the periphery might help to explain the seemingly disparate clinical results of endovascular intervention.