Reduction in thrombotic events with heparin-coated Palmaz-Schatz stents in normal porcine coronary arteries
Hårdhammar, P.A.; van Beusekom, H.M.; Emanuelsson, H.U.; Hofma, S.H.; Albertsson, P.A.; Verdouw, P.D.; Boersma, E.; Serruys, P.W.; van der Giessen, W.J.
Circulation 93(3): 423-430
1996
ISSN/ISBN: 0009-7322 PMID: 8565158 Document Number: 460555
Background: The use of stents improves the result after balloon coronary angioplasty. Thrombogenicity of stents is, however, a concern. In the present study, we compared stents with an antithrombotic coating with regular stents. Methods and Results: Regular stents were placed in coronary arteries of pigs receiving no aspirin (group 1; n=8) or aspirin over 4 weeks (group 2, n=10) or 12 weeks (group 3, n=9). Stents coated with heparin (antithrombin III uptake, 5 pmol/ stent) were placed in 7 pigs that did not receive aspirin (group 4). The other animals received aspirin and coated stents with a heparin activity of 12 pmol antithrombin III/stent (group 5, n=10) or 20 pmol/stent (group 6, n = 10; group 7, n = 10). Quantitative arteriography was performed at implantation and after 4 (groups 1, 2, and 4 through 6) or 12 weeks (groups 3 and 7). In an additional 5 animals, five regular and five coated stents (20 pmol/stent) were placed and explanted after 5 days for examination of the early responses to the implants. Thrombotic occlusion of the regular stent occurred in 9 of 27 in groups 1 through 3. However, in 0 of 30 of the animals receiving high-activity heparin-coated stents (groups 5 through 7), thrombotic stent occlusion was observed (P lt .001). Histological analysis at 4 weeks showed that the neointima in group 6 was thicker compared with its control group 2 (259+- 104 and 117 +- 36 mu-m, P lt .01), but at 12 weeks the thickness was similar (152+-61 and 198+-49 mu-m, respectively). Comparison at 5 days suggested delayed endothelialization of the coating. Conclusions: High-activity heparin coating of stents eliminates subacute thrombosis in porcine coronary arteries.