To Stent or Not to Stent? This is the Renal Artery Stenosis Question
Authors: Doumas Michael , Tziomalos Konstantinos , Athyros Vasilios G. 
Published: February 2014

A few days ago (Nov 18, 2013) the results of the large
prospective 􀀃􀀇􀀑􀀉􀀌􀀐􀀕􀀇􀀒􀀈􀀔􀀍􀀇􀀑􀀁 􀀅􀀔􀀓􀀈􀀐􀀎􀀊􀀒􀀁 􀀌􀀏􀀁 􀀆􀀊􀀏􀀇􀀍􀀁 􀀂􀀓􀀋􀀊􀀑􀀐􀀖
􀀒􀀈􀀍􀀊􀀑􀀐􀀓􀀌􀀈􀀁 􀀄􀀊􀀒􀀌􀀐􀀏􀀒􀀁 􀀗􀀃􀀅􀀆􀀂􀀄􀀘􀀁 􀀓􀀑􀀌􀀇􀀍 were presented and published.
CORAL enrolled 947 participants who had atherosclerotic
renal artery stenosis (ARAS), 􀀂 60% and either
uncontrolled systolic hypertension despite treatment with 􀀂 2
anti-hypertensive drugs or stage 3 chronic kidney disease
(CKD) [1]. CORAL randomly assigned patients to medical
therapy plus renal-artery stenting or medical therapy alone.
The median follow-up period was 43 months and the primary
endpoint was a composite of death from cardiovascular
disease (CVD) or renal causes, myocardial infarction (MI),
stroke, congestive heart failure, progression of renal insufficiency,
or need for renal replacement therapy. Results
showed that the addition of renal-artery stenting to thorough
multifactorial medical therapy did not contribute a significant
clinical benefit with respect to the prevention of CVD
events or renal function deterioration. Adverse CVD or renal
events occurred in 35.1% of patients who received stenting
and 35.8% of those on medical therapy alone (p=0.58) [1].
Thus, the authors concluded that renal artery stenting was
not superior to optimal medical therapy alone for moderately
severe ARAS [1].
The results of CORAL have a direct impact on clinical
practice questioning the need for renal artery stenting in patients
managed with optimal medical therapy. The message
seems to be very simple. If patients have ARAS and high
blood pressure, they need a very aggressive comprehensive
medical therapy before considering any interventional procedure.
A recent meta-analysis investigated CVD outcome in patients
with ARAS treated either with renal angioplasty or
antihypertensive drug therapy [2]. Pooled data from 5 studies
(n=1,159 patients) showed that during the 2-year follow-up
there were no significant clinical outcome differences between
angioplasty and medical therapy [2], both in patients with or without CKD. In another study [3] it was shown that
patients with ARAS and normal or near normal renal function
(creatinine 􀀁2.0 mg/dl) can be safely treated with effective
drug treatment, with a small decrease in GFR. For patients
who have atherosclerotic MI, stroke or renal impairment,
renal artery stenting may further reduce blood pressure
and delay the deterioration or even improve renal function
[3].
The Angioplasty and Stenting for Renal Artery Lesions
(ASTRAL) trial (n =867) [4], although criticised by some for
methodological issues [5], results showed that there were no
meaningful clinical benefit from revascularization in patients
with ARAS; however considerable risks were present [4].
On the other hand, in patients with renovascular hypertension
due to fibromuscular dysplasia (RAFMD) and/or the
combination of RAFMD with ARAS, angioplasty is the
method of choice and has favourable short- and long-term
CVD and renal clinical outcomes [6].

The take away message from all the above is that prior
trials showed similar results in mild ARAS; this study established
the futility of stenting for a higher severity (moderate
severity) of the disease. Substantially severe forms of ARAS
will probably have to undergo renal angioplasty with stenting,
especially when flash pulmonary oedema occurs [7-9].