Stenting for atherosclerotic renal artery stenosis: One poorly designed trial after another

WILL CORAL GIVE US THE ANSWER?

The CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) trial is under way.¹⁹ Enrollment was to have ended on January 31, 2010, and it will be several years before the data are available for analysis.

CORAL, a multicenter study funded in 2004 by the National Institutes of Health, will have randomized more than 900 patients with greater than 60% stenosis to optimal medical therapy alone or optimal medical therapy plus renal artery stenting. Inclusion criteria are a documented history of hypertension on two or more antihypertensive drugs or renal dysfunction, defined as stage 3 or greater chronic kidney disease based on the National Kidney Foundation classification (estimated glomerular filtration rate < 60 mL/min/1.73 m² calculated by the modified Modification of Diet in Renal Disease [MDRD] formula) and stenosis of 60% or greater but less than 100%, as assessed by a core laboratory. The primary end point is survival free of cardiovascular and renal adverse events, defined as a composite of cardiovascular or renal death, stroke, myocardial infarction, hospitalization for congestive heart failure, progressive renal insufficiency, or need for permanent renal replacement therapy.

We hope this trial will give us a clear answer to the question of whether renal artery stenting is beneficial in the patient population studied. One note of caution: recruitment for this trial was difficult and slow. Thus, there were a number of protocol amendments throughout the trial in order to make recruitment easier. Hopefully, this will not be a problem when analyzing the results.

WE ALL AGREE ON THE INDICATIONS FOR STENTING

So, are we really so far apart in our thinking? And is it really “time to be less aggressive” if we follow the precepts below?

All renal arteries with stenosis do not need to be (and should not be) stented.

There must be a good clinical indicationandhemodynamically significant stenosis. This means the degree of stenosis should be more than 70% on angiography or intravascular ultrasonography.

Indications for stenting. Until more data from compelling randomized trials become available, adherence to the American College of Cardiology/American Heart Association guidelines on indications for renal artery stenting is advised³:

• Hypertension: class IIa, level of evidence B. Percutaneous revascularization is reasonable for patients with hemodynamically significant renal artery stenosis and accelerated hypertension, resistant hypertension, and malignant hypertension.
• Preservation of renal function: class IIa, level of evidence B. Percutaneous revascularization is reasonable for patients with renal artery stenosis and progressive chronic kidney disease with bilateral renal artery stenosis or a stenosis to a solitary functioning kidney.
• Congestive heart failure: class I, level of evidence B. Percutaneous revascularization is indicated for patients with hemodynamically significant renal artery stenosis (ie, > 70% stenosis on angiography or intravascular ultrasonography) and recurrent, unexplained congestive heart failure or sudden, unexplained pulmonary edema.