Study: Stenting, Medication Equally Effective at Treating Renal Artery Stenosis

Renal artery stenting is no better than optimal medical therapy alone for treating moderately severe renal artery stenosis, the clinical trial shows.

Adverse cardiovascular or renal events occurred in 35.1 percent of stented patients and 35.8 percent of those on medication alone during three and one-half years of follow-up (P=0.58), Christopher J. Cooper, M.D., of the University of Toledo, Ohio, and colleagues found in the National Institutes of Health-funded Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial. A subgroup analysis in severe renal artery stenosis of 80 percent or greater likewise showed no advantage to stenting.

The results could change treatment for the condition by convincing doctors to attempt medical therapy before stenting, said study co-author Michael Jaff, D.O., a vascular medical specialist and chair of the Massachusetts General Hospital Institute for Heart, Vascular, and Stroke Care in Boston. “The message is very simple: If someone has renal artery stenosis and high blood pressure, they need a very aggressive comprehensive trial of medical therapy before considering any other interventional procedure,” he told MedPage Today. “CORAL clearly defines that the first line therapy for these patients must be comprehensive medical therapy.”

The NIH-funded CORAL trial enrolled patients with at least 60 percent atherosclerotic stenosis of the renal artery plus hypertension despite two or more anti-hypertensive drugs or stage 3 chronic kidney disease. Such patients “should not undergo renal-artery stenting, because the only tangible consequence is the procedure-related risk of bleeding or vascular complications,” argued John A. Bittl, M.D., an interventional cardiologist at Munroe Regional Medical Center in Ocala, Fla..

The trial randomized 947 such individuals to medical therapy with candesartan (Atacand), with or without a thiazide diuretic, and amlodipine/atorvastatin (Caduet) either as the sole management strategy or plus renal artery stenting.

While Bittl noted that inclusion of a thiazide diuretic “might rankle some practitioners,” Jaff said it was a cheap combination regimen with infrequent dosing through the day to maximize compliance.

Over a median follow-up period of 43 months, stenting yielded a hazard ratio of 0.94 for the primary composite endpoint compared with medical therapy alone (95 percent CI 0.76-1.17).

None of the components — death from cardiovascular or renal causes, myocardial infarction, stroke, hospitalization for congestive heart failure, progressive renal insufficiency, and the need for renal-replacement therapy — showed a significant difference between treatment groups either.

“An encouraging finding was that medical therapy alone was associated with a 20 percent rate of the primary end point at two years, which was half the expected rate of 40 percent,” Bittl noted. “The favorable results with medical therapy alone suggest, but do not prove, that the individual drugs used in the trial were beneficial.”

Blood pressure levels modestly but consistently favored the interventional approach, with a 2.3 mm Hg difference between the groups (P=0.03).

But Robert Bonow, M.D., a cardiologist at Northwestern Memorial Hospital in Chicago, Ill., and past president of the American Heart Association, suggested this wouldn’t be enough of an advantage to sway the clinical decision. “As far as a renal artery intervention for treating hypertension, it does not appear that stenting a narrow artery is going to be beneficial,” he told MedPage Today.

Renal denervation, on the other hand, remains promising to fight resistant hypertension, he pointed out.

On the cusp of the U.S. pivotal trial results with that technology, Jaff predicted that the results of CORAL would become increasingly important.

“As people start looking for patients eligible for renal denervation — particularly once one device gets approved — they’re going to find renal artery disease just because they are going to be looking a lot more for it,” he said, noting that a normal renal artery is a requirement for the ablation procedure.