Completing a randomized multicenter study is a bit like writing a screenplay in that it takes about the same amount of time, Ziv Haskal, MD, FSIR, told Medical Device Daily.

That was one of the many lessons Haskal learned while working on a recently published study of 190 patients at 13 centers that has shown the benefit of stent grafts over balloon angioplasty for maintaining function of dialysis access grafts in kidney failure patients who undergo dialysis. At six months, the stent grafts allowed dialysis patients to continue life-saving treatment with significantly fewer interruptions and invasive procedures, according to the study, which was published in the Feb. 11 issue of the New England Journal of Medicine. Until now, no other therapy has proven more effective than angioplasty for these patients.

"This is part of seven years of work, from concept to feasibility to finding an industry partner to designing a trial to educating the FDA that this was a high-need population that had an issue . . . and finally the editorial process [in the NEJM]," said Haskal, vice chair of strategic development and chief of vascular and interventional radiology at the University of Maryland Medical Center (Baltimore).

Haskal said that when he started the study it was "incredibly controversial."

"The idea that you could put a stent graft in this area, the hallowed space where only surgeries could occur, was really a bit of an educational battle," he said.

Hemodialysis is the leading treatment for more than 340,000 U.S. patients with end-stage renal disease or kidney failure, the researchers noted.

"Stent grafts are a game changer for dialysis patients, especially for those who suffer due to the repeated need for invasive procedures to maintain their ability to get dialysis," Haskal said. "This study – the first large prospective controlled study of its kind – shows that this novel therapy [stent grafts] provides clear improvement over balloon angioplasty by prolonging the function of a patient's bypass without surgery – helping individuals avoid additional invasive procedures and time in the hospital."

Haskal, who is also professor of radiology and surgery at the University of Maryland School of Medicine, was the lead investigator and co-author of "Stent Graft Versus Balloon Angioplasty for Failing Dialysis-access Grafts."

"Stent grafts overwhelmingly performed better than balloon angioplasty for maintaining access in dialysis patients, providing superior patency and freedom from repeat interventions. What we've done is arguably supersede the results of surgery by improving the flow dynamics beyond those achievable with an operation."

Thirteen participating sites – including academic, community-based, inpatient and freestanding outpatient dialysis centers – enrolled 190 patients (69 men, 121 women) with failing arteriovenous grafts in this study. Ninety-seven patients received stent grafts, while 93 underwent balloon angioplasty (percutaneous transluminal angioplasty or PTA). There were no significant differences between graft and PTA groups with respect to demographics or relevant medical history, the authors noted. Nearly 51% of dialysis accesses treated with stent grafts remained open at six months, as compared to just 23% of those treated with balloon angioplasties. Treating physicians had a nearly 94% success rate at implanting the stent grafts. There were no differences in adverse events between the two approaches.

"Interventional radiologists work to keep access to the circulatory system open to ensure that patients with end-stage renal disease can continue to receive regular life-saving dialysis," said Brian Stainken, MD, FSIR, president of the Society of Interventional Radiology (Fairfax, Virginia). "This study is another example of the way in which interventional radiologists pioneer advances to improve health care for patients – in this case, specifically for kidney failure patients." Stainken is an interventional radiologist who is also president of the Imaging Network of Rhode Island and chair of the diagnostic imaging department at Roger Williams Medical Center (Providence, Rhode Island).

When kidneys fail – called chronic kidney or end-stage renal disease – treatment in the form of regular dialysis (or hemodialysis) is needed to replace the kidney's job of ridding the body of toxic waste products to maintain fluid, electrolyte and acid-base balance. Before dialysis can begin, patients often have a vascular access graft surgically placed in the arm to provide a high-flow site. This prosthetic fistula (or passageway) works by connecting a patient's vein with an artery in his or her forearm, allowing high flow of blood from the artery into the vein.

Over time, the accesses narrow and block off (occlude) due to buildup of scar tissue. Failing or occluded dialysis access grafts cause considerable morbidity, discomfort and inconvenience for dialysis patients due to the need for invasive procedures to reestablish access flow or to graft abandonment and reoperation. When failure occurs, an interventional radiologist normally performs a balloon angioplasty to reopen the fistula and regain access for dialysis.

Other co-authors of the study were Scott Trerotola, MD, FSIR, of the Hospital of the University of Pennsylvania (Philadelphia); Bart Dolmatch, MD, FSIR, of the University of Texas/Southwestern Medical Center (Dallas); Earl Schuman, MD, of Oregon Surgical Consultants (Portland); Sanford Altman, MD, of the Open Access Vascular Access Center (Miami, Florida); Samuel Mietling, MD, of the Vascular Access Center (Augusta, Georgia); Scott Berman, MD, of Vascular Surgery (Tucson Arizona); Gordon McLennan, MD, FSIR, of the Indiana University School of Medicine (Indianapolis); Clayton Trimmer of the University of Texas/Southwestern Medical Center; John Ross, MD, of the Bamberg County Hospital and Nursing Center (Bamberg, South Carolina); and Thomas Vesely, MD, FSIR, of the Vascular Access Center of Frontenac Grove (Frontenac, Missouri).

"The surprising, or great, outcome [of the study] is not just that it controlled that area, but it really turns down or mutes the stimulus to growing the next narrowing," Haskal said. He added that he does not receive any royalties from sales of the device used in the study.

An accompanying editorial, written by Robert Kerlan, Jr., MD, and Jeanne LaBerge, MD, called "Fistula First, Stent Graft Second," says the superiority of autogenous arteriovenous fistulas as compared with prosthetic artiovenous grafts is well established. Fistulas have a far lower risk of failure and a reduced requirement for revision as compared with prosthetic grafts, Kerlan and LaBerge wrote.

"We absolutely agree [with the editorial]," Haskal said. "But for those patients who may prove to be inadequate candidates for a fistula . . . a stent graft becomes a much more durable and more suitable" option.

Haskal told MDD that he and his fellow researchers are currently enrolling patients in a longer-term, multicenter follow-up study, RENOVA, which will look at long-term outcomes of treating dialysis patients with stent grafts over balloon angioplasty.

Amanda Pedersen, 229-471-4212;
amanda.pedersen@ahcmedia.com