Intervention With Selution SLR™ Agent Balloon for Endovascular Latent Limus Therapy for Failing AV Fistulas (ISABELLA) Trial

The most common problem with haemodialysis arteriovenous fistulas (AVF) and arterio-venous grafts (AVG) is stenosis, which can lead to inadequate dialysis, and eventual access thrombosis. Conventional plain old balloon angioplasty (CBA) is associated with high recurrence rates of stenosis and repeated interventions. The advent of successful drug-eluting technology in the treatment of the coronary vascular bed and subsequent positive accumulating evidence in the peripheral arterial circulation has prompted the use of drug coated balloons (DCB) in the access fistula circuit for venous stenosis and in-stent restenosis. Recent studies suggest that DCBs may significantly reduce re-intervention rates on native and recurrent lesions. The restenosis process is in part or in whole the result of neo-intimal hyperplasia (NIH) and NIH is considered the main culprit in access circuit target lesion stenosis. NIH is the blood vessel's healing response to the barotrauma from the angioplasty process. A critical component of NIH is the cellular proliferative stage with mononuclear leucocytes identified as the primary inflammatory cell type involved. The rationale for drug elution is to block the NIH response with an anti-metabolite such as paclitaxel. It is important to emphasize that the role of drug elution in the treatment of vascular stenosis is not to obtain a good haemodynamic and luminal result but to preserve a good result obtained during POBA from later restenosis due to NIH and minimise reinterventions and readmissions to hospital for what is a frail population of patients.

A meta-analysis performed by Khawaja et al. seemed to suggest that DCBs conferred some benefit in terms of improving target lesion primary patency (TLPP) in AVFs. An updated meta-analysis performed by our own institution recently reinforced that DCB appears to be a better and safe alternative to CBA in treating patients with stenosis within all haemodialysis circuits (fistulas and grafts) based on 6- and 12-months primary patency and increased intervention free period 5. However, this was not reflected in the largest RCT to date of DCB vs CBA in AVF with no superior target lesion patency demonstrated at six months and one and two years follow-up. Another recent meta-analysis found paclitaxel-coated balloons (PCB) showed no statistically significant improvement over conventional balloons in decreasing fistula stenosis in randomized controlled trials but were significant for cohort studies. Hence this shows the heterogeneity of the available data in the literature and the result is dependent on what studies you include in the review. Another reason why the outcome data is variable is that the high-speed blood flow in dialysis access circuits washes a large amount of the paclitaxel away from the target lesion soon after application. A measurement in swine showed that only 20%-30% of paclitaxel was taken up into the coronary artery wall in vivo 15-25minutes after PCB application.

Furthermore, recent attention has been drawn to a possible increase in late mortality signal and lower amputation free survival in patients receiving DCB treatment with paclitaxel for peripheral arterial disease, although this suggestion has not been demonstrated in the data of DCB within the fistula circuit either at 1 or 2 years. In light of these concerns, attention has turned away recently from paclitaxel-based technologies to sirolimus coated platforms. Sirolimus, like paclitaxel, is a potent antiproliferative agent, which has been found to prevent restenosis in the coronary bed and more recently in the peripheral vasculature but to date has not been studied in AVF circuits The aims of the study is to determine the safety and efficacy of the MedAlliance SELUTION SLR 018™ DEB in the treatment of failing AV fistula due to conduit stenosis in patients undergoing renal dialysis.