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.