The pattern of restenosis and vascular remodelling after cold-end radioactive stent implantation

Background: Edge restenosis is a major problem after radioactive stenting. The cold-end stent has a radioactive mid-segment (15.9 mm) and non-radioactive proximal and distal 5.7 mm segments. Conceptually this may negate the impact of negative vascular remodelling at the edge of the radiation. Method and Results: ECG-gated intravascular ultrasound with three-dimensional reconstruction was performed poststent implantation and at the 6-month follow-up to assess restenosis within the margins of the stent and at the stent edges in 16 patients. Angiographic restenosis was witnessed in four patients, all in the proximal in-stent position. By intravascular ultrasound in-stent neointimal hyperplasia, with a >50% stented cross-sectional area, was seen in eight patients. This was witnessed proximally (n=2), distally (n=2) and in both segments (n=4). Echolucent tissue, dubbed the 'black hole' was seen as a significant component of neointimal hyperplasia in six out of the eight cases of restenosis. Neointimal hyperplasia was inhibited in the area of radiation: Δ neointimal hyperplasia=3.72 mm³ (8.6%); in-stent at the edges of radiation proximally and distally Δ neointimal hyperplasia was 7.9 mm³ (19.0%) and 11.4 mm³ (25.6%), respectively (P=0.017). At the stent edges there was no significant change in lumen volume. Conclusions: Cold-end stenting results in increased neointimal hyperplasia in in-stent non-radioactive segments.