INTRACORONARY RADIATION BEFORE STENT IMPLANTATION INHIBITS NEOINTIMA FORMATION IN STENTED PORCINE CORONARY-ARTERIES

Background Stent implantation has been shown to reduce restenosis by e stablishing a larger lumen but not by reducing neointima formation. We have previously shown that ionizing radiation reduced neointima forma tion 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 form ation. Methods and Results Nine normolipemic pigs underwent coronary a ngiography, and segments of the left anterior descending and left circ umflex arteries were chosen as targets for stenting. A high-activity I r-192 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 Sr-90/Y source (a pure beta-emitter) delivering 14 Gy to five segments of coronary vess els that were stented immediately after irradiation. Stent-to-artery r atio was similar in the radiated and the control arteries. Animals rec eived aspirin 325 mg daily and were killed at 28 days. The intimal are a was significantly reduced in the irradiated stented arteries compare d with control arteries treated with stent only (1.98 mm(2) with Ir-19 2 and 2.53 mm(2) with Sr-90/Y versus 3.82 mm(2) in the control stented arteries, P<.005). Conclusions Endovascular radiation before coronary stenting reduces neointima formation and may further reduce the reste nosis rate after stent implantation.