Intracoronary stenting now constitute the majority of coronary interventions, and subsequently in-stent restenosis has become a significant clinical problem. Recently, several studies on intracoronary radiation therapy, in patients with in-stent restenosis, have demonstrated a reduction in binary angiographic restenosis and target lesion revascularization compared with control groups. The effects of beta-radiation therapy on non-stented adjacent segments in in-stent restenosis have not been sufficiently evaluated. beta-radiation therapy for in-stent restenosis was performed with a 188Re-MAG3 filled balloon.

We evaluated, and compared, the effects of beta-radiation therapy on non-stented adjacent segments, in in-stent restenosis, by intravascular ultrasound (IVUS) analysis, between 50 patients who received radiation therapy and 9 controls. The changes (delta: follow-up-post-intervention) of the external elastic membrane (EEM), the lumen and other IVUS variables, were compared between the segments having received radiation therapy and those in the controls.

Significant differences were found between the 2 groups, and were as follows: the delta EEM and delta lumen areas were 0.3mm² and -1.0mm², (p=0.005) and 0.2mm² and -1.3mm², (p<0.001) in those radiated and the controls, respectively.

In conclusion, compared with the changes on the vessel shrinkage of the control group, there was significant vessel enlargement in the non-stented adjacent segments having received radiation therapy.