Timothy P Murphy, Vascular Disease Research Center, Rhode Island Hospital, Providence, USA, and one of the investigators on the CORAL study, told delegates at CIRSE 2016 in Barcelona, Spain, that a low urine albumin:creatinine ratio could be used to help identify a large group of patients with renal artery stenosis who might benefit from stenting.
“These patients might experience improved event-free and overall survival after renal artery stent placement plus optimal medical therapy compared with optimal medical therapy alone,” he said.
“Randomised clinical trials that have used various clinical endpoints have not shown an additional clinical benefit for renal artery stent placement over optimal medical therapy alone. We sought to examine the effect of baseline albuminuria on clinical outcomes after renal artery stent placement,” Murphy explained.
The CORAL (Cardiovascular outcomes in renal atherosclerotic lesions) study was a multicentre, open-label, randomised, controlled trial that compared 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.
The study randomised 947 patients with ≥60% renal artery stenosis to receive medical therapy only or medical therapy plus stenting. Enrolled patients, whose average age was 69 years, had renal artery stenosis and either systolic blood pressure of 150mmHg or higher while taking two or more drugs or stage three (moderate) chronic kidney disease. The primary endpoint was a composite of major cardiovascular or renal events (death from renal or cardiovascular causes, stroke, myocardial infarction, hospitalisation for heart failure, progressive renal insufficiency, and permanent renal replacement therapy).
In 2014, results from the study, published in the New England Journal of Medicine, showed that stenting of the renal artery appears to offer no significant improvement when added to medication-based therapy.
The investigators stratified the CORAL study population (n=826) based on the median baseline urine albumin/creatinine ratio and analysed for the five-year incidence of the primary composite endpoint (myocardial infarction, hospitalisation for congestive heart failure, stroke, renal replacement therapy, progressive renal insufficiency, or cardiovascular- or kidney disease-related death) and overall survival. They compared longitudinal systolic blood pressure between the treatment groups.
Murphy and colleagues found that when baseline urine albumin/creatinine ratio was less than, or equal to, the median value (22.5mg/g), renal artery stenting was associated with a significantly better event-free survival with respect to the primary composite endpoint (73% vs. 59% at five years, p=0.02), cardiovascular disease-related death (93% vs. 85%, p=<0.01), progressive renal insufficiency (91% vs. 77%, p=0.03), and overall survival (89% vs. 76%, p=<0.01). They also reported that there was no benefit with stenting when baseline urine albumin/creatinine ratio was greater than the median value.
The investigators further found no significant difference in longitudinal systolic blood pressure based on the treatment group for baseline urine albumin/creatinine greater than 22.5mg/g, but borderline significance favouring stent treatment was observed when the ratio was less than 22.5mg/g (p=0.052).
“These data raise the question about whether millions of people with atherosclerotic renal artery stenosis could benefit from renal artery stent placement,” Murphy told Interventional News.