Low-energy gamma-emitting stents inhibit intimal hyperplasia with minimal "edge effects" in a pig coronary artery model.
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.
Kutryk
Michael J B
MJ
Roy and Ann Foss Interventional Cardiology Research Program, Terrence Donnelly Heart Center, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
Kuliszewski
Michael A
MA
Jaffe
Ronen
R
Tio
Fermin O
FO
Janicki
Christian
C
Sweet
William L
WL
Sparkes
John D
JD
Strauss
Bradley H
BH
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*
D011868:Radioisotopes; D010165:Palladium