Two-year clinical follow-up of ⁹⁰Sr/⁹⁰ Y β-radiation versus placebo control for the treatment of in-stent restenosis

Background: It is an ongoing concern that intracoronary brachytherapy may possibly just delay the problem of in-stent restenosis ("late catch up"). For γ-radiation, 3 placebo-controlled studies have shown the maintenance of the initially positive effect after 2 years, but similar data do not exist for β-radiation. STents And Restenosis Trial (START) was the first placebo-controlled randomized trial for in-stent restenosis with β-radiation; herein, we report the 2-year clinical follow-up. Methods and Results: Two hundred and forty-four patients were randomized to active treatment, 232 patients to placebo (nonactive source train) treatment. The primary end point of efficacy was target vessel revascularization (TVR); primary safety end point was any major adverse cardiac event (MACE) at 8 months and 2 years. Two-year clinical outcome in patients receiving brachytherapy was based on 195 of 244 original patients (79.9%) and in the placebo arm on 183 of 232 original patients (78.9%). TVR was significantly reduced by 25%; from 36.6% (placebo) to 27.5% (brachytherapy) remained significant after 2 years (RR. 7 [.57-.98], 95% CI -9.2 [-17.5-0.8]). The Kaplan-Meier analysis for TVR and MACE showed improvement beginning approximately 90 days after radiation and remained almost constant for the 2 following years. Freedom from TVR was significantly increased from 62.4% ± 3.8% to 71.6% ± 3.3% (P = .027) and freedom from MACE from 58.9% ± 3.7% to 68.0% ± 3.4% (P = .035). Conclusions: The START trial shows for the first time that the initial beneficial effects of intracoronary brachytherapy with β-radiation using ⁹⁰Sr/⁹⁰Y are maintained at 2-year clinical follow-up period.