title: Low-energy gamma-emitting stents inhibit intimal hyperplasia with minimal "edge effects" in a pig coronary artery model.
abstract: OBJECTIVE
  The objective of this study was to determine the effects of different doses of gamma-emitting radioactive stents on intimal hyperplasia in a porcine coronary stent model at 28 days.
  
  
  METHODS
  Sixty-four bare stents and those coated with palladium-103 [activities of 0 (control), 0.5, 1.0, 2.0, and 4.0 mCi] were implanted in the coronary arteries of 32 pigs. Stented segments were evaluated by histomorphometry at 28 days.
  
  
  RESULTS
  There was significantly more intima in the 0.5- and 1-mCi stents than in controls (4.27+/-0.52 and 4.71+/-1.13 vs. 1.71+/-0.61 mm(2); P<.0001). Neointimal formation in 2-mCi stents was similar to that in controls, while that in 4-mCi stents was reduced compared to that in controls (2.34+/-1.61 and 0.82+/-0.25 vs. 1.71+/-0.61 mm(2); P=NS and P<.05, respectively). Stent margin neointimal response was representative of that within the stent body, with nonsignficant modest increases in intimal area at adjacent nonstented segments in radioactive stent groups. There was a dose-dependent increase in inflammation scores. Radioactive stents had lower intimal smooth muscle and higher fibrin scores. There was an increase in adventitial fibrosis in 1- and 2-mCi stents versus controls (1.26+/-0.99, and 2.25+/-1.27 vs. 0.21+/-0.31; P<.001).
  
  
  CONCLUSIONS
  Dose-response inhibition of in-stent hyperplasia with minimal "edge effects" occurs with low-energy gamma-emitting stents. An increased inflammatory response at higher doses in palladium-103 stents indicates that later follow-up studies are necessary.
authors.affiliation: Roy and Ann Foss Interventional Cardiology Research Program, Terrence Donnelly Heart Center, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Michael J B
authors.initials: MJ
authors.lastname: Kutryk
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuliszewski
authors.forename: Ronen
authors.initials: R
authors.lastname: Jaffe
authors.forename: Fermin O
authors.initials: FO
authors.lastname: Tio
authors.forename: Christian
authors.initials: C
authors.lastname: Janicki
authors.forename: William L
authors.initials: WL
authors.lastname: Sweet
authors.forename: John D
authors.initials: JD
authors.lastname: Sparkes
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Strauss
mesh_terms: D000818:Animals; D001918:Brachytherapy; D023903:Coronary Restenosis / Q000517:prevention & control*; D003331:Coronary Vessels / Q000473:pathology* / Q000528:radiation effects*; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006965:Hyperplasia / Q000532:radiotherapy; D010165:Palladium / Q000627:therapeutic use; D011868:Radioisotopes / Q000627:therapeutic use; D015607:Stents; D034421:Sus scrofa; D016896:Treatment Outcome; D017539:Tunica Intima / Q000473:pathology* / Q000528:radiation effects*
chemical_list: D011868:Radioisotopes; D010165:Palladium