Objectives

The CORAL trial compared the incidence of cardiovascular and renal adverse events for medical therapy alone with medical therapy plus renal-artery stenting in patients with atherosclerotic renal-artery stenosis and elevated blood pressure, chronic kidney disease, or both.

Background

Renal-artery stenosis, which is present in 1 to 5% of people with hypertension, often occurs in combination with peripheral arterial or coronary artery disease. Results of community-based screening suggest that the prevalence among persons older than 65 years of age may be as high as 7%. Renal-artery stenosis may result in hypertension, ischemic nephropathy, and multiple long-term complications. Uncontrolled studies performed in the 1990s suggested that renal-artery angioplasty or stenting resulted in significant reductions in systolic blood pressure and in the stabilization of chronic kidney disease. Subsequently, there were rapid increases in the rate of renal-artery stenting among Medicare beneficiaries, with the annual number of procedures increasing 364% between 1996 and 2000. However, three randomized trials of renal-artery angioplasty failed to show a benefit with respect to blood pressure. Two subsequent randomized trials of stenting did not show a benefit with respect to kidney function. At the time of the CORAL trial, no studies had been designed specifically to assess clinical outcomes.

Given the prevalence of atherosclerotic renal-artery stenosis, this condition is an important public health issue. If stenting prevents the progression of chronic kidney disease and lowers blood pressure, it has the potential to prevent serious health consequences, including adverse cardiovascular and renal events. In contrast, if stenting confers neither of these benefits, it is likely to incur substantial cost without a public health advantage. Therefore, CORAL researchers performed a randomized clinical trial to determine the effects of renal-artery stenting on the incidence of important cardiovascular and renal adverse events.

Participants

Individuals with severe renal-artery stenosis were eligible if they had hypertension with a systolic blood pressure of 155 mm Hg or higher while receiving two or more antihypertensive medications. Severe renal-artery stenosis was defined angiographically as stenosis of at least 80% but less than 100% of the diameter or stenosis of at least 60% but less than 80% of the diameter of an artery, with a systolic pressure gradient of at least 20 mm Hg. During the course of enrollment, the criteria was modified so that patients who did not have systolic hypertension but who had renal-artery stenosis could be enrolled if they had chronic kidney disease, which was defined as an estimated glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m2 of body-surface area. Severe renal-artery stenosis could be identified with the use of duplex ultrasonography, magnetic resonance angiography, or computed tomographic angiography. A total of 5322 patients were screened, and 947 were randomly assigned to stenting plus medical therapy (467 subjects) or medical therapy alone (480 subjects).

Design

Subjects were randomly assigned in a 1:1 ratio to either medical therapy alone or stenting plus medical therapy. All participants in both treatment groups received antiplatelet therapy and other protocol-driven medical therapies to control blood pressure and glucose and lipid levels in accordance with guidelines. Unless otherwise contraindicated, the following medications were mandated by the protocol: the angiotensin II type-1 receptor blocker candesartan, with or without hydrochlorothiazide, and the combination agent amlodipine–atorvastatin, with the dose adjusted on the basis of blood pressure and lipid status. Medications were adjusted until the subject reached the blood-pressure goal of less than 140/90 mm Hg in subjects without coexisting conditions, or less than 130/80 mm Hg in subjects with diabetes or chronic kidney disease. Blood pressure was measured three times, 2 minutes apart, in each participant, with the use of an oscillometric device.

Participants in the stent group underwent placement of a Palmaz Genesis stent. All renal arteries with stenoses of 60% or more were treated. In patients with multiple stenoses, stenting could be performed as a single procedure or in intervals of 2 to 4 weeks.

The primary end point was the occurrence of a major cardiovascular or renal event; a composite of death from cardiovascular or renal causes, stroke, myocardial infarction, hospitalization for congestive heart failure, progressive renal insufficiency, or the need for permanent renal-replacement therapy.

Conclusions

Renal-artery stenting did not confer a significant benefit with respect to the prevention of clinical events when added to comprehensive, multifactorial medical therapy in people with atherosclerotic renal-artery stenosis and hypertension or chronic kidney disease.

N Engl J Med. 2014 Jan 2;370(1):13-22. doi: 10.1056/NEJMoa1310753. Epub 2013 Nov 18.

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