Vascular morphometric changes after radioactive stent implantation: a dose-response analysis.
OBJECTIVE
The goal of this study was to evaluate the dose-dependency of morphometric changes in the coronary arterial wall after radioactive stenting.


BACKGROUND
Radioactive stents have been found to reduce intrastent intimal hyperplasia (IIH) but lead to a characteristic type of restenosis occurring predominantly at the stent edges.


METHODS
Fifteen patients underwent intravascular ultrasound (IVUS) examination after implantation of a P-32 radioactive stent and at the six-month follow-up. The post-stent IVUS measurements on seven predefined locations of each lesion were subjected to a computer algorithm for the development of dose-volume histograms (DVH). Thus, we derived the radiation doses delivered to at least 10% and 90% of the adventitia (DV10, DV90). The IIH and vascular remodeling at follow-up were correlated with the doses in each segment.


RESULTS
The IIH was most pronounced at the stent edges and lowest in the stent-body, whereas we detected a significant expansive remodeling within the stent body. The delivered doses correlated with a decreased IIH (r = 0.52, p < 0.001 for DV10 and r = 0.62, p < 0.001 for DV90) and with expansive remodeling (r = 0.48, p = 0.009 for DV10 and r = 0.50, p = 0.006 for DV90). A DV10 >90 Gy or a DV90 >15 Gy reduced IIH and induced expansive remodeling. Plaque growth was not reduced by radioactive stents.


CONCLUSIONS
The DVH analysis reveals a dose-dependent increase of external elastic lamina area behind radioactive stents, whereas plaque growth is not reduced but inverted into an outward direction from the stent. A DV10 >90 Gy or a DV90 >15 Gy results in a beneficial long-term outcome after radioactive stenting.
Wexberg
Paul
P
Division of Cardiology, Department of Internal Medicine II, University of Vienna, Vienna, Austria. paul.wexberg@akh-wien.ac.at
Kirisits
Christian
C
Gyöngyösi
Mariann
M
Gottsauner-Wolf
Michael
M
Ploner
Meinhard
M
Pokrajac
Boris
B
Pötter
Richard
R
Glogar
Dietmar
D
D001158:Arteries / Q000000981:diagnostic imaging / Q000528:radiation effects / Q000601:surgery; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000209:etiology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000528:radiation effects / Q000601:surgery; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006965:Hyperplasia / Q000209:etiology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015607:Stents; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional