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.

OBJECTIVE

The 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.

METHODS

Forty-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 x 15 mm) or larger femoral arteries (4.0 x 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.

RESULTS

One 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 mm(2) at 28, 90, and 180 days, respectively, and 5.20 +/- 0.97, 3.11 +/- 0.53, and 5.10 +/- 0.80 mm(2) 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).

CONCLUSIONS

The 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.