Stents Are Not The Answer
But Dr. Kalra and nephrologist Stephen C. Textor, MD, disagreed with Dr. White. “Renal stents are not the preferred treatment for most patients with renal artery disease and hypertension,” said Dr. Textor, of the Division of Nephrology and Hypertension at the Mayo Clinic, Rochester, Minn. Many in the kidney world are not enamored with renal artery stents,” he said. “They offer marginal benefit and substantial risks, and they do not address the comorbid disease process.”
While postprocedure deterioration of renal function and stent thrombosis are concerns, the primary issue is the “questionable benefit” of stents in an age of effective medical therapies for atherosclerotic disease, Dr. Textor said.
“It is questionable now, how much we gain by revascularizing the kidney,” he commented.
Two trials are addressing the issue, and preliminary findings suggest the two approaches may be equivalent.
The Angioplasty and Stent for Renal Artery Lesions (ASTRAL) is comparing medical treatment to medical treatment plus stenting in a randomized trial of 806 patients. Early data suggest there is no difference between the arms in terms of salvaging renal function, renal events (acute renal failure, dialysis, transplant, nephrectomy, renal death), BP control, cardiovascular outcomes and mortality. Five-year survival is about 60% per arm, Dr. Kalra reported.
The overall findings were mirrored in the subgroup with the most severe anatomical disease, where results were similar between the arms.
“It is important to recognize that these patients have a very high risk for other conditions,” Dr. Textor pointed out, “including new coronary artery disease, heart failure, stroke, and death—things that do not change much with renal revascularization.”
ASTRAL also showed that revascularization carries its own risks, including major peri- and post-operative complications in 6.4% and minor complications in 15%, Dr. Kalra said. But mortality was just 8% per year, which is lower than observed in previous trials of ARVD patients. This demonstrates that “modern medical therapies” are effective and may help explain the similarities between the arms, he added.
Dr. White pointed out that the ASTRAL trial only enrolled patients about whom clinicians were uncertain as to the best treatment for ARVD. “It did not include patients whom the doctors ‘knew’ needed a stent,” Dr. White said. “Thus, the population was pretty unlikely to benefit from stenting at the start.” A significant bias against treatment benefit was built in, he added, as many of these patients would not be treated with renal stents in the United States.
Additionally, Dr. White noted, only 80% of the patients in the ASTRAL trial who were randomized to receive renal stents actually received them. “When 20% of the randomized group doesn’t get the treatment being assessed, it seriously weakens any conclusion based upon intention to treat and raises concerns over the quality of the interventionalists performing the procedure.”
The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) study, which is currently recruiting more than 1,000 patients, will also examine the benefit of adding revascularization to intensive medical therapy for the prevention of cardiovascular and renal events.
While awaiting the results of these studies, Dr. Kalra said he has “no doubts” that renal revascularization is overused. “But I make the concession that some patients do benefit from it,” he added. “The skill is in being able to identify them.”