Surgery Not Always Best for Narrowed Kidney Arteries
WEDNESDAY, Nov. 11 -- People suffering from blocked renal arteries fare just as well when treated with medication as they do by having the narrowed artery opened and a stent implanted, British researchers report.
"In asymptomatic people with chronic kidney disease -- people with severe hypertension -- there is no benefit from subjecting them to a risky procedure of revascularization," or restoring the blood flow via artery-opening surgery, said Dr. Philip A. Kalra, a consultant nephrologist at Salford Royal Hospital Trust and the University of Manchester in England and a co-author of the study, published Nov. 12 in the New England Journal of Medicine.
Taking a combination of blood-pressure-lowering drugs, cholesterol-lowering drugs such as statins, and aspirin or another anti-clotting drug can control the condition without the risks associated with revascularization surgery, the researchers said.
For the study, the researchers randomly assigned 806 people with atherosclerotic renovascular disease to have revascularization surgery plus medical treatment or medical treatment alone.
In the next five years, the study found no difference between the groups in blood pressure control or kidney function. The groups had a similar number of kidney and heart problems, and the death rates were also found to be similar.
"There was no difference in renal function in the two arms of the study," Kalra said.
In both groups, blood pressure fell by 7 mmHg, on average, after one year and about 12 mmHg after five years, he noted. About 50 percent of the people in each group had a major cardiovascular event, Kalra said, and 40 percent of those in each group died.
However, 23 people who had revascularization surgery experienced serious side effects. This included two people who died and three who had toes or legs amputated, the study noted.
The most common cause of atherosclerotic renovascular disease is the build-up of plaque on the inside of the arteries that supply blood to the kidneys, causing them to narrow and stiffen, or harden. This can lead to high blood pressure and, eventually, severe kidney damage.
Kalra said, though, that certain people can benefit from revascularization, including those with heart failure and people whose kidney function is rapidly worsening.
Dr. Ajay Singh, clinical director of the renal division and director of dialysis at Brigham and Women's Hospital in Boston and an associate professor of medicine at Harvard Medical School, said that renal artery stenosis, or narrowing of the arteries, is thought to be present in 1 percent to 2 percent of the 25 million Americans with high blood pressure.
Data from 2000 show that nearly 20,000 renal angioplasties, the artery-opening surgeries, are performed each year in the United States at a cost of more than $200 million -- a figure that is "likely to be much higher now, nine years later," Singh said.
But he said only limited information exists on whether angioplasties actually make a difference in preserving kidney function and controlling blood pressure.
"This study would suggest not," he said. "While we are awaiting a bigger study from the U.S. National Institutes of Health, called CORAL, all the evidence so far points to treating patients with blood pressure medications rather than balloon angioplasty."
However, Dr. Arif Asif, director of interventional nephrology at the University of Miami Miller School of Medicine, said that the study had a limitation that makes it difficult to really decide which treatment is best.
The limitation was that people were enrolled based on their doctor's discretion, he said. Because of that, Asif said, people who doctors felt would benefit from angioplasty were excluded from the study and underwent surgery.
Considering this limitation, "then, really, we are back to point zero," Asif said. "We truly don't understand if you take that limitation out whether angioplasty and stenting is best or medical therapy is best."
But because of the high complication rate associated with angioplasty, he said, it might be best to start people whose blood pressure is controllable on medical therapy, based on this study.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases as more on renal artery stenosis.
Posted: November 2009