Drug-coated balloon (DCB) angioplasty has been shown to be superior to POBA in the treatment of stenosis in AVF. This is because the very intervention used to treat underlying stenosis by POBA can induce vascular injury and accelerate intimal hyperplasia, resulting in rapid restenosis and need for repeated procedure to maintain vessel patency. The anti-proliferative drug that is coated on the surface of balloon is released to the vessel wall during balloon angioplasty and blunt the acceleration of intimal hyperplasia response, resulting in improved primary patency after angioplasty. Additionally, unlike stents, DCB does not leave a permanent structure that may impede future surgical revision. Recent randomized control trials (RCT) have shown the superiority of paclitaxel durg-coated balloon (PDCB) over POBA in the treatment of stenosis in AVFs. In a large multicenter RCT, PDCB was demonstrated to result in a 6-month target lesion primary patency of 82.2% compared to 59.5% for POBA. However, concerns had also arisen recently in the use of PDCB. In large lower limb studies involving the use of paclitaxel devices, meta-analysis by Katsanos et al had revealed increased late risk mortality in patient that are treated with PDCB or paclitaxel-coated stent.

Sirolimus drug-coated balloon (SDCB) is the new generation of drug eluting balloons that are available in the market. Compared to paclitaxel, sirolimus is cytostatic in its mode of action with a high margin of safety. It has a high transfer rate to the vessel wall and effectively inhibit neointimal hyperplasia in the porcine coronary model. The effectiveness of SDCB in patients with dialysis access dysfunction has been shown in a small pilot study in AVF stenosis and AVG thrombosis. SAVE AVF registry ams to assess the efficacy and safety of SDCB vs PDCB angioplasty.

Inclusion Criteria:

• Age 21-85 years
• Patient who required balloon angioplasty for dysfunctional or thrombosed AVF
• Successful thrombolysis and angioplasty of the underlying stenosis, defined as less than 30% residual stenosis on Digital Subtraction Angiography (DSA) based on visual assessment of the operator and restoration of thrill in the AVF on clinical examination. For concurrent asymptomatic or angiographically not significant central vein stenosis, patients can be included in no treatment is required.
• received either PDCB or SDCB for the treatment of stenosis.

Exclusion Criteria:

• Patient unable to provide informed consent
• Presence of symptomatic or angiographically significant central vein stenosis who require treatment, with more than 30% residual stenosis post angioplasty
• Patients who had underwent stent placement within the AVF circuit
• Sepsis or active infection
• Recent intracranial bleed or gastrointestinal bleed within the past 12 months.
• Allergy to iodinated contrast media, heparin, paclitaxel or sirolimus
• Pregnancy
• Inadequate treatment of underlying stenosis, defined as >= 30% residual stenosis of the underlying lesions.

Patients with dysfunctional AVFs who have undergone balloon angioplasty or thrombolysis with PDCB or SDCB.