Whether reopening narrowed kidney arteries benefits patients is a $1.7 billion question a North American study hopes to answer.
One to three million Americans, most over age 50 and with uncontrolled high blood pressure, have narrowed renal arteries that can reduce kidney function, causing even more blood pressure problems.
"If you have peripheral vascular disease, if you have uncontrolled hypertension, there is a possibility you also are going to have renal artery stenosis," says Dr. Harold Szerlip, nephrologist at the Medical College of Georgia. "The problem is we don't know what to do about it if you do."
Despite the lack of hard evidence about the benefit, about 50,000 times a year, cardiologists and interventional radiologists opt to use stents to reopen renal arteries with significant blockages.
The question remains whether drugs that better control blood pressure and reduce cholesterol work as well or maybe even better.
"We want to know, if we open up these blockages, do we protect their kidneys in the long term? Do we improve their blood pressure control?" says Dr. Deepak Kapoor, interventional cardiologist.
The MCG doctors have joined the Cardiovascular Outcomes in Renal Atherosclerotic Lesions or CORAL study to help find answers.
The National Institutes of Health-funded study, led by the University of Toledo, is enrolling 1,100 patients at nearly 100 sites in the U.S. and Canada to compare medical management versus medicines coupled with stents, stainless steel scaffolds inserted into blood vessels and best known for their use in coronary arteries.
In fact, oftentimes during routine cardiac catheterization while physicians are maneuvering through the body's major arterial highway, the aorta, from the groin area to the heart, incidental narrowing of the renal arteries are found and may be stented.
While Dr. Kapoor believes the extra step of also visualizing the renal arteries doesn't add significant risk to the procedure, the jury is still out on the risk versus benefit of stenting. "We make the kidneys look beautiful, but do we help the patient?" he says.
"There are data out there that suggest you will help maybe 20 percent, hurt 20 percent and in 60 percent it won't do anything," says Dr. Szerlip. "The question is if you are hurting as many people as you are helping, who needs this procedure? This study is designed to answer that question."
For the study, patients suspected to have renal artery disease because of uncontrolled blood pressure, mild renal failure and peripheral vascular disease, will have a renal angiography study, the gold standard for visualizing renal arteries.
A single artery will have to be at least 60 percent blocked for patients to qualify. Participants will be randomized to stenting or medical therapy. They will be followed for three to six years. Lipid lowering and anti-hypertensive medications will be provided to all patients at no costs.
"I have been working with this problem for years, not knowing what to do with my patients," says Dr. Szerlip. "I am thrilled there is now a multi-center, nationally funded trial to give me answers so I can tell my patients."
"Based on the current evidence, we don't have an answer," echoes Dr. Kapoor. "I think this is going to give us one."
For more information about the CORAL study at MCG, call Barbara Lightfoot, study coordinator, at 706-721-9546.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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