Endovascular AVF May Be Viable Option for Vascular Access in Hemodialysis Patients

The recommended method of vascular access is the surgical creation of an arteriovenous fistula (AVF), a technique developed in 1966. At present, only 14% of patients with end-stage renal disease in the United States initiate hemodialysis with an AVF; in addition, prevalent use of AVFs is low in many regions worldwide.

Factors contributing to underuse of AVF include long cumulative waits for surgical consultation and creation of the AVF, a process that can take from 3 to 10 weeks to complete; convenient and time-consuming preoperative visits; patient refusal of surgery; surgical risk; and high early thrombosis of 12% to 26%. Further, maturation of the AVF can be challenging, requiring use of bridging catheters and an average of 1.5 to 3.3 procedures to allow fistula usability.

Using an endovascular approach to create an AVF may reduce vessel trauma and lessen the stimulus for intimal hyperplasia linked with failure of an AVF to mature. Morbidity may also be reduced, improving patient acceptance and fistula use. Charmaine E. Lok, MD, MSc, and colleagues previously reported developmental work regarding a novel magnet-based endovascular technology to create an AVF (endovascular AVF [endoAVF]) at a single-center in a population of young patients with no significant vascular disease.

In the American Journal of Kidney Diseases [http://dx.doi.org/10.1053/j.ajkd.2017.03.026], the researchers reported on results of NEAT (Novel Endovascular Access Trial), an international prospective clinical study designed to assess the safety and efficacy of the technique with multiple operators and in a board population of patients with chronic kidney disease (CKD). The study cohort included consecutive adult non­–dialysis-dependent and dialysis-dependent patients who were referred for creation of vascular access at nine centers in Canada, Australia, and New Zealand. The intervention of interest was use of catheter-based endovascular technology and radiofrequency energy to create an anastomosis between target vessels, resulting in an endoAVF.

A total of 80 patients were enrolled from January 2014 to August 2015. Twelve-month study follow-up was completed by the last participant in August 2016. The current report included data on the 60 patients with full-analysis-set data. Of those 60, mean age at baseline was 59.9 years, 65% were men, 57% had non–dialysis-dependent CKD, and 42% had a central venous catheter in situ. Prior to end point evaluation, one patient died (cardiac causes unrelated to the procedure), and two participants had inadvertent endoAVF sacrifice related to brachial artery complications, yielding evaluable data for 57 participants used for evaluable cohort analysis.

In 98% of cases (59/60), endoAVF creation was successful. In the one unsuccessful case, the investigator used a braided vascular sheath that acted as an energy sink and prevented adequate radiofrequency energy delivery to create the anastomosis.

In the full-analysis-set cohort, the primary efficacy end point (physiologic suitability of the endoAVF for dialysis) was met in 52 of 60 patients (87%; 95% confidence interval [CI}, 75%-94%). In the evaluable cohort, the end point was met in 52 of 57 patients (91%; 95% CI, 81%-97%). Mean brachial artery flow increased from a baseline level of 82 mL/min to 918 mL/min at 3 months (P<.001). There was significant increase in all draining veins from baseline to 3 months (all P<.001). Mean change in vein diameter and mean vein diameters at 3 months (in parenthesis) were: median cubital vein: 1.7 (5.9) mm; cephalic vein: 2.0 (5.2) mm; and basilic vein: 1.8 (6.0) mm.

In patients in the full-analysis set who received dialysis, endoAVF functional usability was 64% (28/44; 95% CI, 48%-78%). Twelve month and cumulative patencies were 69% and 84%, respectively.

There was one adverse event related to the device; most procedural adverse events were related to brachial artery access/exit. Two percent of endoAVFs in the full-analysis-set cohort had thrombosis within 3 months, and 11% within 12 months.

Study limitations cited by the authors included the single-arm design of the study, and the lack of a surgical comparator.

“Endovascular autogenous fistula creation using a radiofrequency magnetic catheter-based system reliably produces fistulas that are physiologically mature and functionally usable for hemodialysis. Functional usability was achieved with few complications, offering patients and clinicians a minimally invasive option for AVF creation,” the researchers said.

Takeaway Points

  1. An endovascular approach to fistula creation without open surgery provides a minimally invasive option for vascular access for patients requiring hemodialysis.
  2. NEAT (Novel Endovascular Access Trial) is a prospective, single-arm, multicenter study designed to assess the safety and efficacy of creating an arteriovenous fistula (AVF) using an endovascular approach (endoAVF).
  3. Results of NEAT demonstrated that an endoAVF can be reliably created using a radiofrequency magnetic catheter-based system.