Renal and cardiovascular outcomes similar to those of medical therapy alone.
PHILADELPHIA—Placing renal artery stents in patients with atherosclerotic renovascular disease is not associated with improved outcomes when compared with optimal medical therapy alone, researchers reported here at the American Society of Nephrology's Renal Week conference.
The findings come from the Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) study, the largest randomized trial of patients with atherosclerotic renovascular disease. Conducted at 58 centers in the United Kingdom, Australia, and New Zealand, the trial recruited 806 patients between 2000 and 2007.
Patients (mean age 71 years, 63% male) were randomized to receive medical treatment alone or to undergo revascularization in addition to medical treatment. The mean percent of stenosis was 76%. Subjects had a mean glomerular filtration rate of 40 mL/min/1.73 m2 and mean BP of 150/76 mm Hg. Measured outcomes included kidney function, BP, major kidney events, major cardiovascular events, and death.
The two groups showed no significant differences in any of the outcome measures. For example, after a mean follow-up of 33 months (range 12 months to seven years), 100 patients in the medical-treatment-only group and 83 in the revascularization group experienced 132 and 109 cardiovascular events, respectively.
Forty-one patients who received medical treatment alone and 43 revascularized patients experienced 53 and 51 renal events, respectively. The four-year mortality rate was 32% in both groups.
Lead nephrologist for the trial, Philip Kalra, MD, told Renal & Urology News that these findings should make physicians carefully consider whether renal revascularization might benefit their patients before undertaking such procedures. “If you have asymptomatic patients who have anatomical severe disease with renal artery stenosis, then there is no benefit with revascularizing them over medical therapy. Medical therapy is just as good,” said Dr. Kalra, a consultant nephrologist and lead researcher at Salford Royal Hospitals and University of Manchester, in the U.K.
“You need to also consider the expense of the angioplasty and stent procedure, and of course, there is a definite small risk to the patients associated with revascularization. At least 10% are likely to have some complication, and about 2% or 3% will have a serious complication, like blocking off [of] a kidney artery or tearing of a vessel. So revascularization should not be performed with impunity.” He did wish to point out that “there are likely to be sub-groups of patients who do benefit from revascularization, and the current need is to find ways of identifying this minority of patients.”
Keith Wheatley, MD, professor of medical statistics at the Birmingham Clinical Trials Unit at the University of Birmingham in the U.K., and principal investigator for ASTRAL, observed: “We were disappointed because you always start off a trial hoping that the treatment you are investigating will turn out to be better and therefore improve patient outcome.”
“Renal stenting is a commonly performed procedure in the U.K and the results from ASTRAL will now mean that there will be fewer performed,” Dr. Wheatley said. “We do need to have longer term follow-up. So, it is not impossible that there might be a longer- term benefit that might start to emerge, but at the moment there is no real sign of that. Cardiovascular events are common in this population, so we are following up long-term to look at heart attacks, strokes, and other vascular events, as well as blood pressure control and long-term survival.”
A previous study conducted by Dr. Kalra and colleagues on the Medicare population has shown that approximately 16% of all patients in the United States who are diagnosed with atherosclerotic renovascular disease are subjected to renal stenting, which translates to at least 20,000 patients a year.