RADAR - A randomised, multi-centre, prospective study comparing best medical treatment versus best medical treatment plus renal artery stenting in patients with haemodynamically relevant atherosclerotic renal artery stenosis

A randomized, multi-center, prospective study comparing best medical treatment versus best medical treatment plus renal artery stenting in patients with hemodynamically relevant atherosclerotic renal artery stenosis (RADAR) - one-year results of a pre-maturely terminated study

BACKGROUND

The indications for conservative "best medical treatment" (BMT) versus additional renal artery stenting are a matter of ongoing debate. The RADAR study aimed to evaluate the impact of percutaneous renal artery stenting on the impaired renal function in patients with hemodynamically significant atherosclerotic renal artery stenosis (RAS).

METHODS

RADAR is an international, prospective, randomized (1:1) controlled study comparing BMT alone versus BMT plus renal artery stenting in patients with duplex sonographic hemodynamically relevant RAS. Follow-up assessments were at 2, 6, and 12 months and at 3 years. The primary endpoint was change in estimated glomerular filtration rate (eGFR) at 12 months.

RESULTS

Due to slow enrollment, RADAR was terminated early after inclusion of 86 of the scheduled 300 patients (28.7%). Change in eGFR between baseline and 12 months was 4.3 ± 15.4 ml/min/1.73 m² (stent group) and 3.0 ± 14.9 ml/min/1.73 m² (BMT group), p > 0.999. Clinical event rates were low with a 12-month composite of cardiac death, stroke, myocardial infarction, and hospitalization for congestive heart failure of 2.9% in the stent and 5.3% in the BMT group, p = 0.526, and a 3-year composite of 14.8% and 12.0%, p = 0.982. At 3 years, target vessel (re-)vascularization occurred in one patient (3.0%) in the stent group and in 8 patients (29.4%) in the BMT group.

CONCLUSION

In RADAR, outcomes of renal artery stenting were similar to BMT. These results have to be interpreted with the caveat that the study did not reach its statistically based sample size.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT00640406. Registered on 17 March 2008.

Endovascular Management of Atherosclerotic Renal Artery Stenosis: Post-Cardiovascular Outcomes in Renal Atherosclerotic Lesions Era Winner or False Alarm?

Renal artery stenosis (RAS) is frequently associated with severe comorbidities such as reduced renal perfusion, hypertension, and end-stage renal failure. In approximately 90% of patients, renal artery atherosclerosis is the main cause for RAS, and it is associated with an increased risk for fatal and non-fatal cardiovascular and renal complications. Endovascular management of atherosclerotic RAS (ARAS) has been recently evaluated by several randomized controlled trials that failed to demonstrate benefit of stenting. Furthermore, the Cardiovascular Outcomes in Renal Atherosclerotic Lesions study did not demonstrate any benefit over the revascularization approach. In this review, we summarized the available data from retrospective, prospective and randomized trials on ARAS to provide clinicians with sufficient data in order to produce useful conclusions for everyday clinical practice.

Balloon angioplasty, with and without stenting, versus medical therapy for hypertensive patients with renal artery stenosis

BACKGROUND

Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Balloon angioplasty with stenting is widely used for the treatment of hypertensive patients with renal artery stenosis but the effectiveness of this procedure in treating hypertension, improving renal function and preventing adverse cardiovascular and renal events remains uncertain. This is an update, to include the results of recent, important large trials, of a review first published in 2003.

OBJECTIVES

To compare the effectiveness of balloon angioplasty (with and without stenting) with medical therapy for the treatment of atherosclerotic renal artery stenosis in patients with hypertension. The following outcomes were compared: blood pressure control, renal function, frequency of cardiovascular and renal adverse events, presence or absence of restenosis of the renal artery, side effects of medical therapy, numbers and defined daily doses of antihypertensive drugs.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2014) and CENTRAL (2014, Issue 4). Bibliographies were also reviewed and trial authors were contacted for more information.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing balloon angioplasty with medical therapy in hypertensive patients with haemodynamically significant renal artery stenosis (greater than 50% reduction in luminal diameter) and with a minimum follow-up of six months.

DATA COLLECTION AND ANALYSIS

Data were extracted independently on trial design, participants, interventions and outcome measures. A formal meta-analysis was completed to assess the effect on blood pressure, renal function and cardiovascular and renal adverse events. Peto's odds ratios (ORs) and corresponding 95% confidence intervals (CI) for dichotomous outcomes and mean differences (MD) and corresponding 95% CIs for continuous variables were calculated.

MAIN RESULTS

Eight RCTs involving 2222 participants with renal artery stenosis were included in the review. The overall quality of evidence included in this review was moderate. Limited pooling of results was possible due to the variable presentation of some of the trial outcomes. Meta-analysis of the four studies reporting change in diastolic blood pressure (BP) found a small improvement in diastolic BP in the angioplasty group (MD -2.00 mmHg; 95% CI -3.72 to -0.27) whilst the meta-analysis of the five studies reporting change in systolic BP did not find any evidence of significant improvement (MD -1.07 mmHg; 95% CI -3.45 to 1.30). There was no significant effect on renal function as measured by serum creatinine (MD -7.99 µmol/L; 95% CI -22.6 to 6.62). Meta-analysis of the three studies that reported the mean number of antihypertensive drugs found a small decrease in antihypertensive drug requirements for the angioplasty group (MD -0.18; 95% CI -0.34 to -0.03). Repeat angiography was only performed on a small number of participants in a single trial and it was therefore not possible to comment on restenosis of the renal artery following balloon angioplasty. Based on the results of the seven studies that reported cardiovascular and renal clinical outcomes there were no differences in cardiovascular (OR 0.91; 95% CI 0.75 to 1.11) or renal adverse events (OR 1.02; 95% CI 0.75 to 1.38) between the angioplasty and medical treatment groups. A small number of procedural complications of balloon angioplasty were reported (haematoma at the site of catheter insertion (6.5%), femoral artery pseudoaneurysm (0.7%), renal artery or kidney perforation or dissection (2.5%) as well as peri-procedural deaths (0.4%)). No side effects of medical therapy were reported.

AUTHORS' CONCLUSIONS

The available data are insufficient to conclude that revascularisation in the form of balloon angioplasty, with or without stenting, is superior to medical therapy for the treatment of atherosclerotic renal artery stenosis in patients with hypertension. However, balloon angioplasty results in a small improvement in diastolic blood pressure and a small reduction in antihypertensive drug requirements. Balloon angioplasty appears safe and results in similar numbers of cardiovascular and renal adverse events to medical therapy.

Clinical outcome of renal artery stenting for hypertension and chronic kidney disease up to 12 months in the J-RAS Study – prospective, single-arm, multicenter clinical study

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) causes renovascular hypertension (HTN) and impairs renal function, leading to chronic kidney disease (CKD). The J-RAS study was a prospective, multicenter study to assess the clinical outcome of renal artery stenting for up to 1 year in Japanese patients with ARAS.

METHODS AND RESULTS

One hundred and forty-nine patients were enrolled between November 2010 and January 2013. The patients were classified into an HTN (n=121) group and a CKD (n=108) group in the primary analysis. The primary efficacy endpoints were change in blood pressure for the HTN group and change in estimated glomerular filtration rate (eGFR) for the CKD group at 1 months. The primary safety endpoint was freedom from major cardiovascular or renal events at 12 months. In the HTN group, the mean systolic blood pressure (SBP) significantly decreased from 161.6 ± 21 mmHg at baseline to 137.0 ± 21 mmHg (P<0.0001). In the CKD group, there was no significant difference in eGFR from 40.7 ± 10 ml·min(-1)·1.73 m(-2)at baseline to 40.8 ± 13 ml·min(-1)·1.73 m(-2)(P=0.32). The primary safety endpoint was 89.4% at 12 months.

CONCLUSIONS

In the J-RAS trial, significant SBP reduction was seen in the HTN group, and stabilization of renal function in the CKD group. Renal artery stenting for ARAS is safe and effective in Japanese patients.

Clinical problems in renovascular disease and the role of nuclear medicine

Although renovascular disease remains defined as a stenosis of the main renal artery or its proximal branches (renal artery stenosis [RAS]), its clinical overview has changed dramatically over the last 15-20 years and its management is more controversial than ever before. The clinical problems, not only diagnosis and treatment but also the relative contribution of different pathophysiological mechanisms involved in the progression of kidney disease, have shifted dramatically. This presentation aims to emphasize the paradigm change revisiting the (recent) past focused on renovascular hypertension (RVH) to the current context of preservation or recovery of threatened renal function in patients with progressive atherosclerotic renovascular disease until its last stage of irreversible "ischemic nephropathy." In the past, the foreground was occupied by RVH, a very rare disease, where the activation of the renin-angiotensin-aldosterone system (RAAS) was supposed to play the major, if not only, role in RVH issues. The retrospective RVH diagnosis was established either on the improvement or, more rarely, on the cure of hypertension after revascularization by, most often, a percutaneous transluminal renal angioplasty with or without a stent placement. At this time, captoptril radionuclide renography was an efficient diagnostic tool, because it was a functional (angiotensin-converting enzyme inhibition), noninvasive test aiming to evidence both the RAAS activation and the lateralization (or asymmetry) of renin secretion by the kidney affected by a "hemodynamically significant" RAS. At present, even if captoptril radionuclide renography could be looked upon as the most efficient (and cost effective in selected high-risk patients) noninvasive, functional test to predict the improvement of hypertension after RAS correction, its clinical usefulness is questioned as the randomized, prospective trials failed to demonstrate any significant benefits (either on blood pressure control or on renal function protection) of the revascularization over current antihypertensive therapy. Today many patients with RVH remain undetected for years because they are treated successfully and at low expense with these new blockers of RAAS. In addition to its well-known role in hemodynamics, angiotensin II promotes activations of profibrogenic and inflammatory factors and cells and stimulates reactive oxygen species generation. The "atherosclerotic milieu" itself plays a role in the loss of renal microvessels and defective angiogenesis. After an "adaptative" phase, ischemia eventually develops and induces hypoxia, the substratum of ischemic nephropathy. Because blood oxygen level-dependent MRI may provide an index of oxygen content in vivo, it may be useful to predict renal function outcome after percutaneous transluminal renal angioplasty. New PET tracers, dedicated to assess RAAS receptors, inflammatory cell infiltrates, angiogenesis, and apoptose, would be tested in this context of atherosclerotic renovascular disease.

The Role of Sonography in Renal Artery Stenosis Evaluation and Stent Placement

A literature review has been conducted to demonstrate the role of duplex sonography in evaluating renal artery stenosis (RAS) as a screening method for patients prior to percutaneous transluminal renal artery stent (PTRAS) placement. The review also evaluates the role of ultrasound surveillance following PTRAS and establishes the overall influence of ultrasound on defining stent efficacy for managing hemodynamically significant renovascular disease. Recent studies have narrowed criteria for intervention through duplex sonographic assessment of RAS to better predict patient benefit and response to stent placement. Studies using sonographic parameters evaluating patients for renal artery stenosis, criteria-dependent stent placement, and postintervention follow-up have shown improved patient response, helping ensure effective and appropriate care in RAS management.

Cardiac events in hypertensive patients with renal artery stenosis treated with renal angioplasty or drug therapy: meta-analysis of randomized trials

BACKGROUND

Cardiac outcome in patients with atherosclerotic renal artery stenosis (ARAS) undergoing percutaneous transluminal renal angioplasty (PTRA) or medical therapy is not yet completely clear. The aim of this study was to perform a meta-analysis of randomized controlled trials to compare the effect of PTRA and medical therapy on nonfatal myocardial infarction in patients with ARAS.

METHODS

We searched for articles reporting cardiovascular outcome, including nonfatal myocardial infarction, in patients with renal artery stenosis randomized to PTRA with/without stenting or medical therapy.

RESULTS

Five studies were identified. The pooled population consisted of 1,159 subjects who experienced 56 nonfatal myocardial infarctions. When compared with medical therapy, the overall relative risk (RR) was 0.85 (95% confidence interval (CI) 0.51-1.42), P = 0.55, for PTRA. There was no significant difference between PTRA and medical therapy according to procedural characteristics (with/without stent placement), mean serum creatinine at follow-up (higher or lower than 2.0 mg/dl), and maximum follow-up length (> or <2 years).

CONCLUSIONS

In patients with ARAS and hypertension, there is a lack of evidence supporting the superiority of PTRA over medical therapy in prevention of nonfatal myocardial infarction. Awaiting for results of ongoing trials, our data and previous data suggest that PTRA and drug therapy have a similar impact on cardiovascular risk reduction in patients with renal artery stenosis and hypertension.

Fibromuscular dysplasia--a rare cause of renovascular hypertension. Case study and overview of the literature data

Renal artery stenosis (RAS) is associated with increased cardiovascular mortality and morbidity and may constitute a treatable cause of secondary hypertension. Fibromuscular dysplasia is frequently affecting children as the main cause of RAS, but is very rare in adults. We present the case of a 19-year-old overweight patient, with no known pathological conditions in her medical history or family background, admitted for severe, pulsing headaches during the past 3 months and increased blood pressure (BP) values for about a month (maximum BP 220/140 mmHg). The initial clinical exam and first-line imagistic methods did not provide a high suspicion for RAS. However, the invasive methods established the diagnosis of right renal artery medial dysplasia. Balloon angioplasty was the treatment of choice.

Clopidogrel use before renal artery angioplasty with/without stent placement resulted in tertiary procedure risk reduction

OBJECTIVE

Contrary to coronary artery literature, the effect of preprocedural clopidogrel on renal artery restenosis (RAR) has not been characterized. This study was designed to evaluate the effect of preprocedural clopidogrel on target vessel revascularization (TVR), reintervention, and restenosis for patients who underwent recurrent renal artery angioplasty.

METHODS

A retrospective analysis of patients treated for RAR in a single tertiary center from January 1999 to December 2009 was conducted. Patients were divided into preadmission use of (1) clopidogrel or (2) aspirin only (acetylsalicylic acid [ASA]) for the initial procedure. TVR was defined as occurrence of a tertiary procedure for symptomatic RAR. Rate of freedom from event (ie, tertiary restenosis and TVR) was analyzed using Kaplan-Meier method.

RESULTS

Eighty-eight interventions were performed on 77 patients with RAR; 66% were females with average (mean ± SEM) age and body mass index of 68.8 ± 1.1 and 28.6 ± 0.8, respectively. Comorbidities included 96% chronic hypertension, 33% diabetes, 76% hyperlipidemia, 20% renal insufficiency, 39% tobacco use, 58% coronary artery disease, and 51% peripheral vascular disease. Clopidogrel use increased significantly during the index procedure from admission 35.2% to discharge 97.7% (P < .001, McNemar test). There was a trend toward risk reduction of a tertiary intervention (23%) for patients admitted on clopidogrel compared with ASA (P = .052). Likewise, there was a trend (P = .051) toward increased freedom from a tertiary intervention, with cumulative freedom at 8 years 93.5% for clopidogrel vs 61% for ASA. No differences were found for restenosis.

CONCLUSIONS

The use of preprocedural clopidogrel was associated with a possible risk reduction of TVR reintervention, but this finding needs to be validated in randomized clinical trial.

[Medicinal or instrumental (corrected) therapy of renal artery stenosis?]

Arteriosclerotic renal artery stenosis (RAS) has an increased incidence in patients with cardiovascular risk factors. Clinically RAS presents in some patients as secondary, sometimes resistant arterial hypertension and in others as chronic renal insufficiency, sometimes with acute renal failure and in a third group both symptoms are observed. Doppler ultrasound plays a central role in the diagnosis of RAS. Therapeutically, it is important to identify hemodynamically relevant RAS before interventional therapy is initiated. The therapy of RAS has been under intensive debate since the publication of randomized controlled trials (RCT) which showed that only a subset of RAS can be successfully treated by interventional therapy. Since then the medicinal therapy of RAS has gained more and more impact. The following questions are raised: which forms of RAS can be treated by which therapy? What is the best medicinal therapy to treat RAS? What substances are recommended?

Percutaneous renal artery intervention versus medical therapy in patients with renal artery stenosis: a meta-analysis

AIMS

Patients with renal artery stenosis are treated with percutaneous intervention, but randomised studies are inconclusive. We aimed to compare renal percutaneous revascularisation versus medical therapy.

METHODS AND RESULTS

A systematic search for randomised controlled studies yielded three studies comparing renal angioplasty and two studies comparing renal angioplasty with stenting versus medical therapy, respectively. Six sets of data were extracted focusing on systolic and diastolic blood pressure as well as serum creatinine at follow-up. The five trials included 1,030 patients with renal artery stenosis. There was a trend toward, but no significant improvement in, systolic blood pressure (weighted mean difference [WMD] -2.76 mmHg, 95% confidence interval (CI) -5.71 to 0.18; p=0.07), diastolic blood pressure, (WMD -1.18 mmHg, 95% CI -2.69 to 0.32; p=0.12), or serum creatinine (WMD -7.26 mmol/L, 95% CI -14.99 to 0.47; p=0.07) in the patients who underwent percutaneous intervention compared to the medical therapy group. All but one trial showed at least a moderate overall bias risk.

CONCLUSIONS

We did not find a significant improvement in blood pressure or renal function in patients with renal artery stenosis treated with renal artery revascularisation compared to medical therapy alone. However, trial quality was a limitation.

Randomized trials in angioplasty and stenting of the renal artery: tabular review of the literature and critical analysis of their results

As the incidence of hypertension (HTN) continues to rise, finding the optimal treatment of this multifactorial disease is critical. Renal artery stenosis (RAS) is a known etiology for HTN and is associated with declining renal function. Other than medications, the original gold standard for treatment of HTN from RAS was with an open surgical revascularization or nephrectomy. Since then, endovascular interventions for RAS have been reported to be technically possible, but their efficacy over medications or surgery has yielded conflicting results in case series and randomized trials. This tabular review summarizes the results of randomized trials that compared the outcomes of endovascular renal artery interventions with nonendovascular techniques (including medical and surgical treatments) for the treatment of HTN and renal dysfunction. Based on these data, the strengths and weaknesses of individual trials are critically analyzed to better define the methods to identify and treat patients with RAS.

Renovascular hypertension: screening and modern management

The diagnosis and management of patients with renovascular disease and hypertension continue to elude healthcare providers. The advent of novel imaging and interventional techniques, and increased understanding of the pathways leading to irreversible renal injury and renovascular hypertension, have ushered in commendable attempts to optimize and fine-tune strategies to preserve or restore renal function and control blood pressure. Large randomized clinical trials that compare different forms of therapy, and smaller trials that test novel experimental treatments, will hopefully help formulate innovative concepts and tools to manage the patient population with atherosclerotic renovascular disease.

Validity of Estimated Glomerular Filtration Rates for Assessment of Baseline and Serial Renal Function in Patients With Atherosclerotic Renal Artery Stenosis

Background—

Despite routine use of estimated glomerular filtration rates (GFRs) as major renal end points in clinical trials of renal revascularization, serial GFR estimates have never been validated in patients with renal artery stenosis (RAS). The purpose of this study was to evaluate the validity of GFR estimates in patients with atherosclerotic RAS.

Methods and Results—

Serum creatinine (SCr) and 125 I-iothalamate GFR (I-GFR) were measured in patients with RAS. GFR estimates were calculated from Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Cockroft-Gault (CG) formulas. Using I-GFR as the reference standard, the sensitivity, specificity, and receiver operating characteristic area under the curve (AUC) were determined for MDRD, CKD-EPI, CG, and reciprocal SCr for identifying I-GFR <60 mL/min per 1.73 m 2 and a 20% change in I-GFR over time. Between 1998 and 2007, 541 I-GFR measurements were performed in 254 consecutive patients with RAS. MDRD, CKD-EPI, and CG GFR estimates demonstrated good sensitivity (86% to 95%), modest specificity (67% to 71%), and good reliability (AUC, 0.86 to 0.94) for identifying I-GFR <60 mL/min per 1.73 m 2 . GFR estimates had good specificity (87% to 95%), poor sensitivity (0% to 45%), and poor reliability (AUC, 0.61 to 0.65) for detecting 20% changes in I-GFR over follow-up.

Conclusions—

In patients with RAS, GFR estimates demonstrate good sensitivity and modest specificity for identifying I-GFR <60 mL/min per 1.73 m 2 but poor sensitivity and reliability for detecting 20% changes in I-GFR. GFR estimates should not be used in clinical trials as major end points to assess serial GFR after renal revascularization.

Predictors of clinical outcome after stent placement in atherosclerotic renal artery stenosis: a systematic review and meta-analysis of prospective studies

OBJECTIVE

To determine clinical predictors for blood pressure and/or renal function improvement after renal artery stent placement in atherosclerotic renal artery stenosis (ARAS).

METHODS

We searched PubMed, EMBASE and Cochrane databases for prospective studies investigating clinical predictive variables for renal function and/or blood pressure improvement after stent placement in ARAS. Eleven studies (1552 participants) were selected for our systematic review and meta-analysis. Meta-regression analysis was performed to investigate heterogeneity and to determine independent predictors for the outcome variables. Bias was evaluated by use of the Cochrane risk of bias tool.

RESULTS

Multivariate meta-regression analysis showed no predictors for renal function improvement. High baseline diastolic blood pressure (DBP) and pulse pressure were significantly associated with the decrease in blood pressure after intervention. These results were consistent with the predictors reported by the individual studies. Meta-analysis showed a nonsignificant decline in serum creatinine of 4.7 μmol/l [95% confidence interval (Cl) -13.8 to 4.5]. Overall, systolic blood pressure (SBP) fell by 19.2 mmHg (95% Cl -22.7 to -15.7) and DBP decreased 8.9 mmHg (95% Cl -10.8 to -7.0). Risk of bias was present in the majority of the studies.

CONCLUSIONS

The present review did not find a clinical characteristic that reliably predicts renal function outcome. High baseline pulse pressure predicted a smaller decrease in SBP after intervention and the best clinical predictor for a larger DBP reduction was a high pretreatment DBP.

Atherosclerotic renal artery stenosis: review of pathophysiology, clinical trial evidence, and management strategies

Renal artery stenosis is prevalent and commonly encountered by cardiovascular specialists. Recently published randomized studies have provoked tremendous controversies in the treatment strategy with regard to renal artery stenting. However, these studies are inconclusive because of major study limitations. As such, cardiovascular specialists are uncertain of the indications or utility of renal revascularization, with differing opinions on management by nephrologists and cardiologists. A greater understanding of this disease process, especially with regard to its functional significance and consequence and treatment strategies based on well-designed clinical trials, is sorely needed. Our review focuses on atherosclerotic renal artery stenosis, with an emphasis on indications for revascularization and review of current trial data.

Primary stenting for atherosclerotic renal artery stenosis

INTRODUCTION

Endovascular treatment for atherosclerotic renal artery stenosis (ARAS) was first performed >30 years ago and its use has increased rapidly since then. However, only recently have large randomized trials rigorously evaluated its clinical benefit.

METHODS

We systematically reviewed the controlled studies on primary stenting for atherosclerotic renal artery stenosis. Studies were included if they compared the outcome of stenting with other treatments, or the outcome associated with different stent characteristics or stenting methods.

RESULTS

Stenting is preferred over angioplasty alone and over surgery when revascularization is indicated for ostial ARAS, except in cases of coexistent aortic disease indicating surgery. Randomized controlled trials showed no significant benefit and substantial risk of renal artery stenting over medication alone in patients with atherosclerotic ARAS without a compelling indication. Improvements in the procedure, such as with distal embolic protection devices and coated stents, are not associated with better clinical outcomes after stent placement for ARAS.

CONCLUSION

Recent evidence shows that impaired renal function associated with ARAS is more stable over time than previously observed. Optimal medical treatment should be the preferred option for most patients with ARAS. Only low-level evidence supports compelling indications for revascularization in ARAS, including rapidly progressive hypertension or renal failure and flash pulmonary edema.