Positive Geometric Vascular Remodeling Is Seen After Catheter-Based Radiation Followed by Conventional Stent Implantation but Not After Radioactive Stent Implantation

Background —Recent reports demonstrate that intracoronary radiation affects not only neointimal formation but also vascular remodeling. Radioactive stents and catheter-based techniques deliver radiation in different ways, suggesting that different patterns of remodeling after each technique may be expected. Methods and Results —We analyzed remodeling in 18 patients after conventional stent implantation, 16 patients after low-activity radioactive stent implantation, 16 patients after higher activity radioactive stent implantation, and, finally, 17 patients who underwent catheter-based radiation followed by conventional stent implantation. Intravascular ultrasound with 3D reconstruction was used after stent implantation and at the 6-month follow-up to assess remodeling within the stent margins and at its edges. Preprocedural characteristics were similar between groups. In-stent neointimal hyperplasia (NIH) was inhibited by high-activity radioactive stent implantation (NIH 9.0 mm 3 ) and by catheter-based radiation followed by conventional stent implantation (NIH 6.9 mm 3 ) compared with low-activity radioactive stent implantation (NIH 21.2 mm 3 ) and conventional stent implantation (NIH 20.8 mm 3 ) ( P =0.008). No difference in plaque or total vessel volume was seen behind the stent in the conventional, low-activity, or high-activity stent implantation groups. However, significant increases in plaque behind the stent (15%) and in total vessel volume (8%) were seen in the group that underwent catheter-based radiation followed by conventional stent implantation. All 4 groups demonstrated significant late lumen loss at the stent edges; however, edge restenosis was seen only in the group subjected to high-activity stent implantation and appeared to be due to an increase in plaque and, to a lesser degree, to negative remodeling. Conclusions —Distinct differences in the patterns of remodeling exist between conventional, radioactive, and catheter-based radiotherapy with stenting.