BACKGROUND: Repeat drug-eluting stenting is superior to balloon angioplasty for prevention of recurrent in-stent restenosis (ISR), but carries a potential disadvantage of multiple layers of stent. The safety and effectiveness of a sirolimus drug-eluting balloon as an alternative has not been assessed. STUDY DESIGN AND METHODS: The SELUTION4ISR trial is a prospective, multi-center, single-blinded, randomized, controlled trial. A total of 418 subjects with bare metal or drug-eluting stent (DES) ISR with up to 2 previous stent procedures at the target lesion, lesion length <
26 mm and reference diameter ≥2.0 mm - ≤4.5 mm will be randomized 1:1 to treatment with either the SELUTION SLR™ DEB (SLR DEB) or standard of care (SOC), which includes either repeat DES or balloon angioplasty without drug coating. A subset of subjects will undergo planned angiographic and optical coherence tomography follow-up. The primary endpoint will be target lesion failure, defined as cardiac death, target vessel myocardial infarction, or clinically-driven target lesion revascularization at 12 months follow-up. The study will sequentially assess non-inferiority of the SLR DEB to SOC in the overall cohort, followed by non-inferiority then superiority of the SLR DEB to DES in the cohort with only 1 previous stent at the target lesion. TRIAL REGISTRATION: The trial is registered at Clinicaltrials.gov (NCT04280029). CURRENT STATUS: The trial completed enrollment in July 2024. CONCLUSION: The SELUTION4ISR study will evaluate the safety and effectiveness of SLR DEB in a prospective, randomized, international, multi-center trial for treatment of coronary ISR.