Background: Intracoronary radiation therapy (IRT) prevents recurrent in-stent restenosis, but its long-term safety and efficacy remain uncertain. In the present study, the long-term clinical outcome of IRT using the rhenium-188 ((188)Re)-filled balloon system was evaluated.
Methods and results: After successful catheter-based treatment of either a de novo or restenotic lesion, 187 patients were randomly assigned to either the radiation (N=104) or the control (N=83) group. The (188)Re-filled balloon system was designed to deliver 17.6 Gy to 1.0-mm tissue depth. Angiographic restenosis was significantly reduced with IRT at 9 months (18.9% vs 45.9%, p<0.001), but the incidence of major adverse cardiac events (MACE) including death, myocardial infarction, and target-vessel revascularization (TVR) by 3 years showed no difference. Lack of clinical benefit might be related to TVR caused by geographic miss (6/22, 28.6%), balloon-induced unhealed dissection (3/22, 13.6%) and late thrombosis (2/22, 9.1%). In the restenotic subgroup (N=39), the MACE rate within 3 years was significantly reduced with IRT (14.3% vs 54.5%, p=0.01).
Conclusions: IRT using the (188)Re -filled balloon system is safe and technically feasible. Although IRT failed to show favorable outcomes for de novo lesion, the clinical benefits for restenotic lesions seem durable for 3 years. Furthermore, preventing geographic miss and dissection might improve long-term outcomes.