Reduction in thrombotic events with heparin-coated Palmaz-Schatz stents in normal porcine coronary arteries.
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.
Hårdhammar
P A
PA
Department of Cardiology, Thoraxcenter, Erasmus University Rotterdam, The Netherlands.
van Beusekom
H M
HM
Emanuelsson
H U
HU
Hofma
S H
SH
Albertsson
P A
PA
Verdouw
P D
PD
Boersma
E
E
Serruys
P W
PW
van der Giessen
W J
WJ
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
D006493:Heparin; D001241:Aspirin