PURPOSEAnimal and clinical studies using radioactive 32P stents have showed largely disappointing results for its high rate of edge restenosis . In contrast, a short half-life, high dose-rate ^Y ft emitting stents more closely mimics the deliver dose rate characteristics of clinically effective P - and y -wire and balloon brachytherapy devices. We studied the long-term effect of a new 90Y -emitting coronary stents in canine coronary injure model and its dose-response characteristics.METHODS90Y radioactive stents were made from electronical-deposition method. Nakedonstents and Y radioactive stents with different radiation dose (2.12, 3.30, 5.14 H C) were implanted in normal canine coronary injure model. Thirty-two animals were divided into four groups: nonradioactive controls (n=10), low dose (n=8), middle dose (n=7) and high dose (n=7). Quantitative coronary angiography were performed at 3rd and 6th month. Histologic endpoints were evaluated at 6th month.RESULTSCoronary angiography found no different results between four group at 3rd and 6th month. Histological observation atfer 6 months found that there were4intima proliferation more or less in four groups. Analysis with the use of computer-assisted system showed that luminal stenosis within stent segment was significantly increased in nonradioactive or low-activity group compared with middle and high-activity group (37.7?.2%, 44.9?0.1% versus 24.2 ?.7%, 22.9 ?.9%) . Pathologic evidence of edge restenosis was seen in three radioactive stent groups. The luminal stenosis in adjacent, nonstented coronary segments were obviously higher in low, middle and high activity groups compared with nonradioactive stent group ( 31.0 ?.7%, 35.1?5.6%, 36.9 + 9.4% versus 21.1 ?.2%).CONCLUSIONSAlthough ^Y P -emitting stent has some unique characteristics including short half-life, higher dose-rate, it could not prevent the restenosis after stent implantation in canine coronary artery injure model and has probably an adverse effect on neointimal formation within stent segments and at the edge of stent.