September 15, 1995
View Full PaperIntracoronary Radiation Before Stent Implantation Inhibits Neointima Formation in Stented Porcine Coronary Arteries
Key Result
Endovascular irradiation before coronary stenting significantly reduced intimal area compared to stent alone (1.98 mm2 with 192Ir and 2.53 mm2 with 90Sr/Y vs 3.82 mm2; P<.005).
Study Design
Type
RCT (n=12)
Randomization
random assignment
Structured PICO
Does endovascular irradiation before stent implantation reduce neointima formation in a porcine coronary artery model?
P
Population
12 normolipemic pigs undergoing coronary stenting, evaluated at 28 days.
I
Intervention
Endovascular irradiation (14 Gy using 192Ir or 90Sr/Y source) followed immediately by 3.5-mm tantalum stent implantation. Animals received aspirin 325 mg daily.
C
Comparator
Stent implantation only without prior irradiation (control arteries)
O
Outcome
Intimal area at 28 dayssurrogate
Endovascular radiation before coronary stenting significantly reduces neointima formation in a porcine model, suggesting a potential strategy to reduce in-stent restenosis.
Main Result
Absolute Event Rate: 1.98% vs 3.82%
p-value: p=<.005
Abstract
BACKGROUND: Stent implantation has been shown to reduce restenosis by establishing a larger lumen but not by reducing neointima formation. We have previously shown that ionizing radiation reduced neointima formation after balloon injury in a swine model of restenosis. The purpose of this study was to determine whether endovascular irradiation of the coronary artery before stent implantation would affect neointima formation. METHODS AND RESULTS: Nine normolipemic pigs underwent coronary angiography, and segments of the left anterior descending and left circumflex arteries were chosen as targets for stenting. A high-activity 192Ir source was used to deliver 14 Gy by random assignment to one of the vessels. After this, 3.5-mm tantalum stents were implanted in both arteries. Three additional pigs were treated with a 90Sr/Y source (a pure beta-emitter) delivering 14 Gy to five segments of coronary vessels that were stented immediately after irradiation. Stent-to-artery ratio was similar in the radiated and the control arteries. Animals received aspirin 325 mg daily and were killed at 28 days. The intimal area was significantly reduced in the irradiated stented arteries compared with control arteries treated with stent only (1.98 mm2 with 192Ir and 2.53 mm2 with 90Sr/Y versus 3.82 mm2 in the control stented arteries, P < .005). CONCLUSIONS: Endovascular radiation before coronary stenting reduces neointima formation and may further reduce the restenosis rate after stent implantation.