Dose-response effects of 32P radioactive stents in an atherosclerotic porcine coronary model.
BACKGROUND
Experimental studies have demonstrated that 32P radioactive stents reduce neointimal formation at 28 days in porcine iliac and coronary arteries. Our objective was to determine the long-term dose-response effects of 1.0- to 12.0-microCi 32P radioactive stents in a porcine atherosclerotic coronary model.


RESULTS
Control (n=19) and 1.0- to 12.0-microCi 32P radioactive (n=43) stents (total, n=62) were implanted in the coronary arteries of 31 miniature swine at 28 days after creation of a fibrocellular plaque by overstretch balloon injury and cholesterol feeding. Angiography and histomorphometry were performed at 6 months. Stent thrombosis occurred in 3 radioactive (7.7%) and no control stents (P=0.54). On histology, the mean neointimal area and the percent in-stent stenosis correlated positively with increasing stent activity (r=0.64, P<0.001). The mean neointimal area (mm2) for the stents with >/=3.0 microCi 32P (3.57+/-1.21) was significantly greater than that for the nonradioactive stents (1.78+/-0.68, P<0.0001). The neointima of the stents with >/=3.0 microCi 32P was composed of smooth muscle cells, matrix proteoglycans, calcification, foam cells, and cholesterol clefts.


CONCLUSIONS
Continuous low-dose-rate irradiation delivered by high-activity (32)P radioactive stents promotes the formation of an "atheromatous" neointima after 6 months in this experimental model. These data may be useful for predicting late tissue responses to radioactive stents in human coronary arteries.
Carter
A J
AJ
Cardiology Research Foundation, Washington Hospital Center, Walter Reed Army Medical Center, Washington, DC 20100, USA. ajc2@mhg.edu
Scott
D
D
Bailey
L
L
Hoopes
T
T
Jones
R
R
Virmani
R
R
D000818:Animals; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000628:therapy*; D003328:Coronary Thrombosis / Q000209:etiology; D003331:Coronary Vessels / Q000473:pathology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D009131:Muscle, Smooth, Vascular / Q000000981:diagnostic imaging* / Q000473:pathology; D010761:Phosphorus Radioisotopes / Q000627:therapeutic use*; D015607:Stents / Q000009:adverse effects; D013552:Swine; D013556:Swine, Miniature
D010761:Phosphorus Radioisotopes