In the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) study, 947 patients who had atherosclerotic renal artery stenosis and either systolic hypertension while taking two or more antihypertensive medications or chronic kidney disease were evaluated. It was a multi-center, open-label, randomized, controlled trial. Patients were randomized to either medical therapy plus renal artery stenting or medical therapy alone .
Previous randomized trials on renal angioplasty had failed to show significant benefit in control of blood pressure [2,3]. Another two randomized trials checking the effect of renal artery stenting in atherosclerotic renal artery stenosis did not show any benefit with respect to kidney function [4.5].
Adverse cardiovascular and renal events were checked in the CORAL study. Composite end point was death from cardiovascular or renal causes, myocardial infarction, stroke, hospitalization for congestive heart failure, progressive renal insufficiency or need for renal replacement therapy. Median follow up period in the trial was 43 months . There were no significant differences in all cause mortality or the individual components of the primary composite endpoint between the study and control groups. There was a modest decrease of systolic blood pressure in the stenting group (mean 2.3 mm Hg). Final data reported was from 931 participants, after excluding one center due to quality issues.
Authors were considering whether the medical therapy given to CORAL participants can be replicated in clinical practice to reap similar benefits. The medical therapy in the study included angiotensin receptor blocker with or without a thiazide diuretic and amlodipine for control of blood pressure. The patients received antiplatelet agents and atorvastatin also . The trial had enrolled patients with renal artery stenosis of 60% or more. Though this might be considered as a limitation, there was no benefit among the participants with more than 80% stenosis either. Another potential issue was the 210 patients excluded by the physicians. It is likely that physicians felt that they may benefit from stenting due to the severity of the disease.
CORAL study complements the findings of ASTRAL  and STAR  trials, which did not find a benefit on kidney function from renal artery stenting in atherosclerotic renal artery stenosis.