Gamma II Localized Radiation Therapy to Inhibit Restenosis - GAMMA II


Safety and efficacy registry of Ir-192 (14 Gray) to treat in-stent restenosis


A simplified treatment regimen using gamma-radiation brachytherapy is effective in reducing recurrent in-stent restenosis

Study Design

Study Design:

Patients Enrolled: 125
Mean Follow Up: 9 months

Patient Populations:

Angina or myocardial ischemia In-stent restenosis >60% Reference vessel diameter 2.75-4.0mm Lesion length <45 mm Successful intervention on restenotic lesion

Primary Endpoints:

Composite endpoint of death, MI, and TLR at 9 months

Drug/Procedures Used:

Patients wtih in-stent restenosis were treated with gamma-radiation using a manually-driven afterloader with Ir-192 seed ribbons with a noncentered closed end lumen catheter. Source trained lengths of 23, 39, and 55 mm (6,10,and 14 seeds) were used. Unlike the Gamma I trial, a fixed dosimetry model of 14 gy at 2mm radius was used in Gamma II. Primary endpoints were clinical events at 9 months and angiographic results at 6 months. The average lesion length was 19.08 0.36 mm and the reference vessel diameter was 2.7 0.5 mm. All the data was analysed at an independent core lab.

Principal Findings:

9 month angiographic follow up is available in 86% of the patients with 52% decrease in in-stent restenosis (p 0.001)compared to the placebo arm of the Gamma I study and 40% decrease in the in-lesion restenosis (p 0.001). The 9 month MACE decreased by 36% compared to the placebo arm of the Gamma I study (p = 0.009) and decrease in TLR by 48% (p = 0.001). Similar 6% late stent closure was noted.


The Gamma II trial is a registry of patients who receive brachytherapy. It was conducted in follow-up to the Gamma I trial. The Gamma II registry gathered data regarding restenosis rates associated with slightly higher fixed dose regimen of gamma intracoronary radiation therapy. This registry experience was compared in a non-randomized fashion to the Gamma I placebo arm. This non-randomized analysis suggested improved 6 month angiographic and 9 month clinical results with this simplified fixed dosing regimen.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Stable Ischemic Heart Disease, Chronic Angina

Keywords: Coronary Restenosis, Iridium Radioisotopes, Brachytherapy, Stents

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