RESUMEN
BACKGROUND: Intracoronary gamma-radiation reduces recurrent in-stent restenosis. Late thrombosis (>30 days after radiation therapy) is identified as a serious complication. The Washington Radiation for In-Stent Restenosis Trial (WRIST) PLUS, which involved 6 months of treatment with clopidogrel and aspirin, was designed to examine the efficacy and safety of prolonged antiplatelet therapy for the prevention of late thrombosis. METHODS AND RESULTS: A total of 120 consecutive patients with diffuse in-stent restenosis in native coronary arteries and vein grafts with lesions <80 mm underwent percutaneous coronary transluminal angioplasty, laser ablation, and/or rotational atherectomy. Additional stents were placed in 34 patients (28.3%). After the intervention, a closed-end lumen catheter was introduced into the artery, a ribbon with different trains of radioactive (192)Ir seeds was positioned to cover the treated site, and a dose of 14 Gy to 2 mm was prescribed. Patients were discharged with clopidogrel and aspirin for 6 months and followed angiographically and clinically. All patients but one tolerated the clopidogrel. The late occlusion and thrombosis rates were compared with the gamma-radiation-treated (n=125) and the placebo patients (n=126) from the WRIST and LONG WRIST studies (which involved only 1 month of antiplatelet therapy). At 6 months, the group receiving prolonged antiplatelet therapy had total occlusion and late thrombosis rates of 5.8% and 2.5%, respectively; these rates were lower than those in the active gamma-radiation group and similar to those in the placebo historical control group. CONCLUSIONS: Six months of clopidogrel and aspirin and a reduction in re-stenting for patients with in-stent restenosis treated with gamma-radiation is well tolerated and associated with a reduction in the late thrombosis rate compared with a similar cohort treated with only 1 month of clopidogrel and aspirin.