Year : 2010 | Volume
: 26 | Issue : 4 | Page : 607--608
Revascularisation for atherosclerotic renal artery stenosis: Is it worthwhile?
TJ Nirmal, Shanmugasundaram Rajaian, Nitin S Kekre
Department of Urology, Christian Medical College, Vellore, India
Nitin S Kekre
Department of Urology, Christian Medical College, Vellore
|How to cite this article:|
Nirmal T J, Rajaian S, Kekre NS. Revascularisation for atherosclerotic renal artery stenosis: Is it worthwhile?.Indian J Urol 2010;26:607-608
|How to cite this URL:|
Nirmal T J, Rajaian S, Kekre NS. Revascularisation for atherosclerotic renal artery stenosis: Is it worthwhile?. Indian J Urol [serial online] 2010 [cited 2020 Apr 10 ];26:607-608
Available from: http://www.indianjurol.com/text.asp?2010/26/4/607/74486
This multicenter, randomized trial compared the clinical outcomes of percutaneous revascularization Vs medical therapy for atherosclerotic renal artery stenosis (RAS).  Patients with uncontrolled/ refractory hypertension or unexplained renal dysfunction were screened with relevant imaging and laboratory tests. 806 patients with substantial atherosclerotic stenosis in at least one renal artery were then randomized to medical therapy plus revascularization or medical therapy alone. Primary outcome was renal function, as measured by the reciprocal of the serum creatinine level. Secondary outcomes were effects on blood pressure and number of blood pressure medications, time to renal and major cardiovascular events, and mortality. The median follow-up was 34 months. At one year after randomization, the average number of antihypertensive taken by each patient was slightly higher in the medical therapy group (2.97 versus 2.77, P=0.03). More patients in the revascularization group were receiving renin-angiotension blockers at baseline (47% versus 38%, P=0.02) and at one year (50% versus 43%, P=0.05). The rate of progression of renal impairment, as measured by the mean slope of the reciprocal of the serum creatinine level over time, did not differ significantly between the two groups. The only secondary outcome that differed between the two groups was reduction in diastolic blood pressure, which was better with medical therapy (P=0.03). In total, there were 31 serious complications from revascularization in 23 patients including pulmonary edema, myocardial infarction and peripheral gangrene. There were two deaths. The authors conclude that the risks associated with endovascular revascularization for atherosclerotic renal artery stenosis far outweighed the clinical benefits.
Since renal revascularization was developed in the early 1990s, lack of definitive evidence supporting intervention has fuelled the debate between interventionalists and medical therapists. A recent meta-analysis of five randomized controlled trials including 984 patients failed to show an improvement in renal function but showed improvement in systolic blood pressure at 3-24 months follow-up in patients treated with renal artery revascularization compared to medical therapy alone. 
The ASTRAL (angioplasty and stenting for renal artery lesions) trial is the largest study till date which examines the role of renal artery stenting in atherosclerotic renal artery stenosis. Large numbers, stratified randomization, intention to treat analysis contribute to the strengths of this study. However, the trial has been criticized for its inclusion criteria, which favored enrollment of patients without clinically significant RAS but with other co morbidities. 
Even though 59% had a significant stenosis (>70%), they failed to show clinical benefit from revascularization. This questions the role of intervention in asymptomatic individuals with mild to moderate stenosis and serves to reinforce the guidelines laid down by the American Heart Association for stenting in RAS.  These results also imply the futility of screening for renal artery stenosis among those with atherosclerosis and chronic kidney disease or hypertension.
However, one of the drawbacks of this trial is the likely exclusion of the subgroup of patients who may have actually benefitted from revascularization i.e. those presenting with acute kidney injury or flash pulmonary edema.  The rate of serious complications following revascularization was much higher at 6.8% vs. 2%, reported in similar studies conducted in the U.S, casting a doubt on the quality of interventions.
The caveat in the ASTRAL study is that it compared medical therapy with a minimally invasive treatment. Literature is replete with data supporting long term therapeutic efficacy and safety of surgical revascularization in atherosclerotic RAS. Novick et al . have probably the largest series of surgical revascularization. A lower preoperative serum creatinine level and bilateral RAS were significant predictive factors for a favorable renal functional outcome.  Since they did open surgery and had access to renal histology, they were able to show that presence of atherosclerotic renal emboli in the kidney was a poor outcome measure in addition to the other parameters. The authors in the ASTRAL study did not have access to this parameter and hence it is possible that their conclusions could be skewed. Hence the merits of newer forms of therapy such as percutaneous revascularization must be weighed against these results in order to get a more balanced picture of various therapeutic alternatives.
In conclusion, the value of percutaneous revascularization in atherosclerotic RAS is yet to be established and results from ongoing long term randomized trials such as the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions)  may help settle the debate.
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