Optimizing dosimetry with high-dose intracoronary gamma radiation (21 Gy) for patients with diffuse in-stent restenosis.

Abstract Background The efficacy of intracoronary gamma radiation (IRT-γ) in reducing recurrent in-stent restenosis (ISR) is well established using doses of 14–18 Gy. We sought to examine whether an escalation in dose to 21 Gy is safe and confers additional benefit in reducing repeat revascularization and major adverse cardiac events (MACE) in patients with diffuse ISR. Methods Forty-seven patients with diffuse ISR (lesion length 20–80 mm) in native coronary arteries ( n =25) and saphenous vein grafts ( n =22) underwent percutaneous transluminal coronary angioplasty and/or additional stents followed by IRT-γ using the Checkmate system (Cordis) with a dose of 21 Gy. All patients were discharged with clopidogrel for 12 months and aspirin indefinitely. Six-month angiographic and 12-month clinical outcomes of these patients were compared to 120 patients treated with 18 Gy using the same system. Results At baseline, patients in the 21-Gy group had more multivessel, vein graft disease and history of prior myocardial infarctions and coronary artery bypass grafts ( P P Conclusions IRT-γ therapy for diffuse ISR lesions with a 21-Gy dose is clinically safe and feasible with marked reduction in late loss but does not confer additional benefit with regard to repeat revascularization and MACE when compared to a dose of 18 Gy.