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Reference: N Engl J Med 2014 Jan 2;370(1):13-22 (level 2 [mid-level] evidence)
Renal artery stenosis (RAS) may cause hypertension and worsening kidney function. Stenting of renal arteries has been proposed to decrease deterioration of kidney function and help control hypertension in patients with renal artery stenosis. It is hoped that this will decrease the risk of developing cardiac events such as myocardial infarction. However, randomized control trials have failed to show substantial benefit to blood pressure control or kidney function and there has been no study with the primary outcome being adverse cardiovascular or renal events.
The Cardiovascular Outcome in Renal Atherosclerotic Lesions (CORAL) trial was a multicenter, open-label, randomized, controlled trial to test the hypothesis that stenting for atherosclerotic RAS can prevent adverse cardiovascular and renal events. 947 participants (mean age 69 years) were randomly assigned to 2 groups: 467 participants in the stent plus medical therapy group and 480 participants in the medical therapy alone group. All patients had severe atherosclerotic renal artery stenosis and either systolic hypertension on 2 or more anti-hypertensive medications or an estimated glomerular filtration rate (GFR) of < 60 ml/min/1.73 m2. Medications used included candesartan with or without hydrochlorothiazide and combined atorvastatin-amlodipine. Blood pressure goal was less than140/90 in patients with no coexisting conditions and 130/80 in patients with diabetes mellitus or chronic kidney disease. The participants were followed for a median 43 months. The primary end point was a composite of death from any cardiovascular or renal cause and occurrence of major cardiovascular or renal events. Major cardiovascular events included myocardial infarction, stroke, or congestive heart failure requiring hospitalization for at least 12 hours with the need for intravenous therapy (vasodilators, diuretics, or inotropes) during hospitalization. Renal events included the need for permanent renal-replacement therapy and progressive renal insufficiency which is defined as 30% or more reduction in GFR for at least 60 days with no other attributable cause. Secondary clinical end points were the individual components of the primary outcome.
The primary outcome rates were not statistically different between groups. The primary composite outcome occurred in 35.1% in stent plus medications group compared to 35.8% in medical therapy alone group (P=0.58). In addition, no individual component of the primary composite outcome was statistically different between groups. Furthermore, there was no significant difference in all-cause mortality between groups.
The trial had some limitations. Severe stenosis was defined as either stenosis of at least 80% but less than 100% or stenosis of at least 60% but less than 80% plus 20 mm hg systolic pressure gradient. However, there is no consensus on the degree of stenosis for which intervention is recommended. Another limitation is this study cannot be applied to patients with fibromuscular dysplasia as these patients were excluded from the study.
In brief, superiority of stenting of stenotic atherosclerotic renal arteries plus medical therapy over medical therapy alone for prevention of cardiovascular and renal events in patients with renal artery stenosis was not demonstrated. Per the American College of Cardiology (ACC) and American Heart Association (AHA) recommendations, revascularization is indicated for patients with significant renal artery stenosis and either unexplained heart failure or unexplained pulmonary edema. Also, revascularization may be an option in patients with progressive chronic kidney disease with bilateral RAS or in patients with RAS and inadequately controlled hypertension. However, these recommendations may need to be modified given the CORAL study results.
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