Multicentre RCT comparing paclitaxel-coated, sirolimus-coated balloons to uncoated control in 642 patients with AVF, over 3 years, followed for 1 year. Primary endpoint: time to loss of treatment segment primary patency (TSPP). Secondary endpoints: time to loss of primary patency at any treatment segment, access circuit primary patency, AVF abandonment, total interventions, adverse events, patient quality of life, intima-media thickness, and degree of stenosis. Randomisation minimises by site, previous intervention, AVF location, and treatment segments. Follow-up every 3 months for 1 year, with ultrasound assessments at selected sites. Measures to avoid bias include blinded follow-up and primary endpoint adjudication by independent radiologists. Safety assessed through SAEs related to treatment or access circuit, reported within 24 hours.