BACKGROUND: Radioactive stents have been reported to reduce in-stent neointimal thickening. An unexpected increase in neointimal response was observed, however, at the stent-to-artery transitions, the so-called "edge effect." To investigate the factors involved in this edge effect, we studied stents with 1 radioactive half and 1 regular nonradioactive half, thereby creating a midstent radioactive dose-falloff zone next to a nonradioactive stent-artery transition at one side and a radioactive stent-artery transition at the other side. METHODS AND RESULTS: Half-radioactive stents (n=20) and nonradioactive control stents (n=10) were implanted in the coronary arteries of Yucatan micropigs. Animals received aspirin and clopidogrel as antithrombotics. After 4 weeks, a significant midstent stenosis was observed by angiography in the half-radioactive stents. Two animals died suddenly because of coronary occlusion at this mid zone at 8 and 10 weeks. At 12-week follow-up angiography, intravascular ultrasound and histomorphometry showed a significant neointimal thickening at the midstent dose-falloff zone of the half-radioactive stents, but not at the stent-to-artery transitions at both extremities. Such a midstent response (mean angiographic late loss 1.0 mm) was not observed in the nonradioactive stents (mean loss 0.4 to 0.6 mm; P< 0.01). CONCLUSIONS: The edge effect of high-dose radioactive stents in porcine coronary arteries is associated with the combination of stent injury and radioactive dose falloff.

Additional Metadata
Keywords Animals, Blood Vessel Prosthesis Implantation, Coronary Angiography, Coronary Vessels/pathology/*radiation effects/surgery, Disease Models, Animal, Disease Progression, Dose-Response Relationship, Radiation, Drug Implants, Female, Graft Occlusion, Vascular/*etiology/pathology/*prevention & control, Implants, Experimental, Phosphorus Radioisotopes/*administration & dosage, Research Support, Non-U.S. Gov't, Stents/*adverse effects, Swine, Miniature, Tunica Intima/pathology/radiation effects, Vascular Patency/radiation effects, angioplasty, radioisotopes, restenosis, stents
Persistent URL dx.doi.org/10.1161/hc4301.097873, hdl.handle.net/1765/9781
Journal Circulation (Baltimore)
Citation
van der Giessen, W.J, Harteveld, M.S, Coen, V.L.M.A, Bhagwandien, R.E, Au, A, Ligthart, J.M.R, … Boersma, H. (2001). "Edge Effect" of 32P Radioactive Stents Is Caused by the Combination of Chronic Stent Injury and Radioactive Dose Falloff. Circulation (Baltimore), 104(18), 2236–2241. doi:10.1161/hc4301.097873