Use of localised intracoronary β radiation in treatment of in-stent restenosis:: the INHIBIT randomised controlled trial

Background In-stent restenosis is a major limitation of intracoronary stenting. lonising gamma radiation has been shown to reduce recurrence of restenosis after stent placement. We aimed to compare the effects of intracoronary beta radiation treatment with those of placebo for clinical and angiographic outcomes of patients with diffuse in-stent restenosis. Methods 332 patients with in-stent restenosis underwent successful coronary intervention, and were then randomly allocated to intracoronary beta radiation with a phosphorus-32 source (n=166) or placebo (166) delivered into a centreing balloon catheter through an automatic afterloader. Longer lesions (>22 mm of dilated length) were treated with tandem positioning of the study wire. The primary safety endpoint was major adverse cardiac events, defined as death, myocardial infarction, and repeat target-lesion revascularisation at 9 months. The primary efficacy endpoint was binary angiographic restenosis rate in the analysis segment during 9-months' follow-up. Analysis was by intention to treat. Findings Procedural success, and in-hospital and 30-day complications were similar among the two groups. 24 (15%) patients in the radiated group had the primary safety endpoint of death, myocardial infarction, or repeat target-lesion revascularlsation over 290 days compared with 15 (31%) in the placebo group (difference 16% [95% CI 7-25], p=0.0006). Binary angiographic restenosis rate was lower in the radiated group than the placebo group for the entire analysed segment (difference 25% [14-37], p<0.0001). Interpretation Vascular brachytherapy using pure beta-emitter P-32 delivered into a centreing catheter via an automatic afterloader can be used to reduce overall revascularisation in patients undergoing treatment for diffuse in-stent restenosis.