Jorg Hausleiter, Adnan Kastrati, Julinda Mehilli, Helmut Schuhlen, Franz Dotzer, Christoph Goos, Gisela Pogatsa-Murray, Michael Vogeser, Martin Breuer, Josef Dirschinger, Albert Schomig, The OSIRIS Study Group, German Heart Center Munich, Munich, Germany, 1. Medizinische Klinik, Klinikum rechts der Isar, Munich, GermanySirolimus coated stents are a promising new therapy for restenosis in de-novo coronarylesions. Except for the promising results achieved with brachytherapy, the treatment ofrecurrent in-stent-restenosis (ISR) remains a challenging clinical issue. Given the effi-cacy of systemic administration of Sirolimus to prevent neointimal hyperplasia in animalmodels and to halt and even reverse the progression of allograft vasculopathy, it seemsreasonable to consider this drug as a good option for oral treatment to prevent recurrentISR. This randomized, double-blind, placebo-controlled study is aimed at evaluating theefficacy of 2 different regimens of oral Sirolimus in patients with ISR treated with repeatPTCA. We enrolled 300 patients with ISR in native coronary arteries who were randomlyassigned to one of three treatment arms: usual-dose Sirolimus, high-dose Sirolimus andplacebo. All patients in the two treatment arms received Sirolimus loading two days priorto and the day of intervention followed by maintenance therapy for 7 days. The differencebetween usual- and high-dose arms was in the amount of pre-treatment, 8 mg in theusual-dose Sirolimus arm and 24 mg in the high-dose Sirolimus arm. The maintenancetherapy after intervention consisted of 2mg/d for 7 days in both arms. Angiographicbinary restenosis at 6-months angiography was the primary end point of the study. Sam-ple size was estimated to give sufficient power to the trial for detecting a 25 and 50%reduction of the binary restenosis with the two Sirolimus doses. Angiographic and 1-yearclinical follow-up is in progress and will be completed in January 2004. The final studyresults will be presented.