AVF Treatment Leaves a Great IMPRESSION

The first data from a randomized controlled trial looking into the treatment of arteriovenous fistula (AVF) stenosis was announced today by Tan Chieh Suai, Clinical Associate Professor and Head of the Department of Renal Medicine at Singapore General Hospital (Singapore). A nephrologist by training, Dr Tan has a special interest in interventional nephrology, and his subspecialty in renal medicine focuses specifically on access dysfunction in dialysis patients.

The trial in question is IMPRESSION (SIroliMus coated angioplasty versus plain balloon angioplasty in the tREatment of dialySis access dysfunctION),¹ which was initiated 3 years ago. It was necessary because the mid- to long-term patency of the current standard treatment, plain balloon angioplasty (PBA), was far from satisfactory. “What was frustrating for me, and is also the case for most patients, is that when you have a dysfunctional access, the patency from PBA post-intervention is at most 50% at 6 months,” he told LINC Today. “If half of the patients that you treat are back in 6 months, it’s a never-ending cycle.”

Although paclitaxel-coated balloons have been shown to be more effective than PBA, the now well-known meta-analysis from a few years ago questioned the safety profile of paclitaxel.

“Of course, now we have clarified the doubts about paclitaxel, but at the time this trial was being conceptualized, there was an association with death,” noted Dr Tan. Therefore, Dr Tan focused on a sirolimus-coated balloon (SCB), which seemed more acceptable, particularly to his specialty. “Nephrologists are very comfortable with sirolimus because they already use it as an immunosuppression medication to prevent organ rejection,” he explained. “Now that it could be coated onto a balloon, it was a very attractive alternative to paclitaxel.”

To that end, his group trialed the MagicTouch SCB (Concept Medical) following pilot studies that had shown encouraging results.^2–4 In IMPRESSION, the results have been extremely positive: “We found that about 70% of patients with dysfunctional access that we treated with an SCB will remain patent, meaning that only 30% come back within 6 months,” said Dr Tan. “And hopefully we’re affording them a better quality of life.

“We are very excited that we finally have an alternative to paclitaxel. We found that in patients who have had high-quality PBA, the addition of an SCB helps improve patency.”

IMPRESSION is unique in that Dr Tan and his fellow investigators, including Drs Tan Ru Yu, Chong Tze Tec, Tay Kiang Hiong, Edward Choke and Ho Pei, did not restrict drug-coated treatment to single target lesions, as is the case in many trials. “In this study we designed it so that all stenoses in the circuit are treated, because in this part of the world, many of our patients have multiple lesions,” he explained. “And that’s what is exciting about the whole study.

“We have shown that if you treat like this, these patients are not going to come back within 6 months. That is the main thrust of the study—to be as close to real life as possible.”

Dr Tan disagrees that using cutting or high-pressure balloons before applying the SCB has influenced the study results in some way. But the IMPRESSION protocol does mirror what he does in real-world situations. “When we have a resistant lesion that is not amenable to PBA, we will use a cutting balloon or ultra-high-pressure balloon to efface the stenosis.”

Because the study was conducted in Singapore with a predominantly Asian cohort, the plan is now to extend to an investigational device exemption study via the Food and Drug Administration in the US, and further afield.

Adding his take-home message, he remarked: “If you perform good-quality angioplasty and add on an SCB, you’re going to get much more mileage compared to what you’re doing currently.”

References

1. Pang SC, Tan RY, Choke E, et al. SIroliMus coated angioPlasty versus plain balloon angioplasty in the tREatment of dialySis acceSs dysfunctION (IMPRESSION): study protocol for a randomized controlled trial. Trials. 2021;22(1):945. 

2. Tang TY, Soon SXY, Yap CJQ, et al. Early (6 months) results of a pilot prospective study to investigate the efficacy and safety of sirolimus coated balloon angioplasty for dysfunctional arterio-venous fistulas: MAgicTouch Intervention Leap for Dialysis Access (MATILDA) Trial. PLoS ONE. 2020;15(10): e0241321.

3. Tan CW, Tan RY, Pang SC, et al. Single-center prospective pilot study of sirolimus drug-coated balloon angioplasty in maintaining the patency of thrombosed arteriovenous graft. J Vasc Interv Radiol. 2021;32(3):369–375.

4. Tang TY, Soon SX, Yap CJ, et al. Endovascular salvage of failing arterio-venous fistulas utilising sirolimus eluting balloons: Six months results from the ISABELLA trial. J Vasc Access. 2023;24(5):1008–1017.