title: Reduction in thrombotic events with heparin-coated Palmaz-Schatz stents in normal porcine coronary arteries.
abstract: 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.
  
  
  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 < .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 microns, P < .01), but at 12 weeks the thickness was similar (152 +/- 61 and 198 +/- 49 microns, 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.
authors.affiliation: Department of Cardiology, Thoraxcenter, Erasmus University Rotterdam, The Netherlands.
authors.forename: P A
authors.initials: PA
authors.lastname: Hårdhammar
authors.forename: H M
authors.initials: HM
authors.lastname: van Beusekom
authors.forename: H U
authors.initials: HU
authors.lastname: Emanuelsson
authors.forename: S H
authors.initials: SH
authors.lastname: Hofma
authors.forename: P A
authors.initials: PA
authors.lastname: Albertsson
authors.forename: P D
authors.initials: PD
authors.lastname: Verdouw
authors.forename: E
authors.initials: E
authors.lastname: Boersma
authors.forename: P W
authors.initials: PW
authors.lastname: Serruys
authors.forename: W J
authors.initials: WJ
authors.lastname: van der Giessen
mesh_terms: D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D001241:Aspirin / Q000008:administration & dosage; D017023:Coronary Angiography; D003328:Coronary Thrombosis / Q000517:prevention & control*; D003331:Coronary Vessels / Q000473:pathology; D004867:Equipment Design; D005500:Follow-Up Studies; D006493:Heparin / Q000008:administration & dosage*; D006965:Hyperplasia; D015607:Stents; D013552:Swine; D017539:Tunica Intima / Q000473:pathology
chemical_list: D006493:Heparin; D001241:Aspirin