The benefit of renal artery stenting in patients with atheromatous renovascular disease and advanced chronic kidney disease

Improving outcomes in atherosclerotic renovascular disease: importance of clinical presentation and multi-disciplinary review

BACKGROUND AND OBJECTIVES

Atherosclerotic renal artery stenosis may cause hypertension, chronic kidney disease and heart failure, but large randomized control trials to date have shown no major additional benefit of renal revascularization over optimal medical management. However, these trials did not consider outcomes specifically in relation to clinical presentations. Given that atherosclerotic renal artery stenosis is a heterogenous condition, measures of success likely differ according to the clinical presentation. Our retrospective study objectives were to determine the effects of revascularization when applied to specific clinical presentations and after careful multi-disciplinary team review.

METHODS

All patients presenting to our centre and its referring hospitals with radiological findings of at least one renal artery stenosis > 50% between January 2015 and January 2020 were reviewed at the renovascular multi-disciplinary team meeting with revascularization considered in accordance with international guidelines, notably for patients with anatomically significant renal artery stenosis, adequately sized kidney and presentations with any of; deteriorating kidney function, heart failure syndrome, or uncontrollable hypertension. Optimal medical management was recommended for all patients which included lipid lowering agents, anti-platelets and anti-hypertensives targeting blood pressure ≤ 130/80 mmHg. The effect of revascularization was assessed according to the clinical presentation; blood pressure and number of agents in those with renovascular hypertension, delta glomerular filtration rate in those with ischaemic nephropathy and heart failure re-admissions in those with heart failure syndromes.

RESULTS

During this 5-year period, 127 patients with stenosis ≥ 50% were considered by the multidisciplinary team, with 57 undergoing revascularization (17 primarily for severe hypertension, 25 deteriorating kidney function, 6 heart failure syndrome and 9 for very severe anatomical stenosis). Seventy-nine percent of all revascularized patients had a positive outcome specific to their clinical presentation, with 82% of those with severe hypertension improving blood pressure control, 72% with progressive ischaemic nephropathy having attenuated GFR decline, and no further heart failure admissions in those with heart failure. Seventy-eight percent of patients revascularized for high grade stenosis alone had better blood pressure control with 55% also manifesting renal functional benefits.

CONCLUSIONS

Multi-disciplinary team discussion successfully identified a group of patients more likely to benefit from revascularization based on 3 key factors: clinical presentation, severity of the renal artery lesion and the state of the kidney beyond the stenotic lesion. In this way, a large proportion of patients can clinically improve after revascularization if their outcomes are considered according to the nature of their clinical presentation.

Endovascular treatments of atherosclerotic renovascular disease: a narrative review and literature search

In recent years, endovascular treatments have become more common in patients with renal artery stenosis and aneurysm. Although the treatment algorithms are not universally accepted, endovascular therapy can be readily utilized for the appropriate indications in the context of surgical treatment for renovascular diseases. The most important factor to consider is that the correct indication is applied for such treatment. Although the applied procedures are believed to have minimal risk, any complications that occur may result in major problems. Moreover, the pathology that is being treated (e.g., hypertension, high serum creatinine concentration, or low glomerular filtration rate) must be well defined. As stent and balloon technologies continue to be developed, more positive results are expected in the coming years. In the present study, we reviewed the endovascular treatment algorithms for atherosclerotic renovascular disease and performed a narrative review of the current literature.

The Maintained Glycemic Target Goal and Renal Function Are Associated with Cardiovascular and Renal Outcomes in Diabetic Patients Following Stent-Supported Angioplasty for Renovascular Atherosclerotic Disease

Patients with type 2 diabetes mellitus (T2DM) constitute a large proportion of patients with atherosclerotic renal artery stenosis (ARAS). However, the mechanism of impaired renal function and hypertension in this subset of patients is multifactorial. We aimed to investigate whether, in diabetic patients, renal function (RF), systolic (SBP) and diastolic blood pressure (DBP) values following stent-supported angioplasty (PTA) for ARAS have an impact on cardiovascular and renal outcomes. Methods: The study group included 93 patients with T2DM and resistant hypertension who underwent PTA for ARAS. The pre- and post-procedure (6 to 12, and 24 months) values of SBP, DBP, eGFR and glycaemia were obtained. The prospective follow-up of median 44 months was performed for combined outcome: major cardiac and cerebral events (MACCE) and progression to renal replacement therapy (RRT). Results: MACCE-RRT occurred in 46 (49.5%) patients, with higher incidence in patients with higher values of SBP (147.8 ± 25.8 vs. 136.7 ± 15.8 mmHg, p = 0.006), DBP (80.8 ± 13.3 vs. 74.4 ± 12.3 mmHg, p = 0.009), chronic kidney disease in stages 3B to 5 (p = 0.029) and those who have not obtained target glycemic goals compared to well-maintained T2DM (p = 0.007) at 24-months. On multivariate Cox analysis, well-maintained T2DM targets [Hazard Ratio (HR):0.27; 95% Confidence Interval (CI):0.13−0.57; p < 0.001], eGFR below 45 mL/min/m2 (HR: 2.20; 95%CI: 1.20−4.04; p = 0.011), previous stroke (HR:2.52; 95%CI:1.19−5.34; p = 0.015) retained their associations with MACCE-RRT, while BP values were not associated with the outcome. Conclusions: The post-procedural RF, maintained glycemic target goal and previous stroke are vital for the outcome in patients undergoing PTA for renovascular disease in diabetic patients.

[Treatment of renal artery stenosis in the year 2021]

Severe arteriosclerotic stenosis of the renal artery with at least 60-70% narrowing of the lumen can lead to various diseases: in the case of unilateral stenosis it can lead to renovascular hypertension, in the case of bilateral narrowing (or in a stenotic solitary kidney) also to an often progressive renal insufficiency (ischemic kidney disease) and/or to acute pulmonary edema (pulmonary flash edema). Renal artery stenosis may be treated by revascularization using either percutaneous (balloon angioplasty with or without stenting) or less commonly open surgical procedures, both with excellent primary patency rates of over 90%; however, randomized trials of catheter-based interventions have failed to demonstrate a longer term benefit with respect to blood pressure control and renal function as well as improved overall survival over optimal medicinal management alone. Due to improved clinical outcomes interventional revascularization is justified in cases with critical stenoses and clinical sequelae, such as pulmonary flash edema and progressive renal failure. Careful patient selection is essential to maximize a potential clinical benefit.

Contrast-Enhanced Ultrasound Assessment of Renal Parenchymal Perfusion in Patients with Atherosclerotic Renal Artery Stenosis to Predict Renal Function Improvement After Revascularization

Background

Identifying patients with atherosclerotic renal artery stenosis (ARAS) who will be improved in renal function after percutaneous transluminal renal artery stenting (PTRAS) is crucial since most patients show no worthwhile benefit of PTRAS. Although the assessment of renal parenchymal perfusion is useful for the identification, few studies predict the renal functional improvement by evaluating the characteristics of renal perfusion.

Objective

The aim of this study was to assess the renal parenchymal perfusion in ARAS patients with contrast-enhanced ultrasonography (CEUS) and predict the benefits of renal function after PTRAS utilizing time-intensity curve (TIC) parameters.

Methods

Thirty-eight kidneys in 30 ARAS patients received PTRAS in this study. They were divided into moderate stenosis group (n=25) and severe stenosis group (n=13) and mild dysfunction group (n=14) and moderate dysfunction group (n=24) according to the degree of renal stenosis and radioisotope glomerular filtration rate (rGFR). The baseline assessment of renal function and renal parenchymal perfusion were performed for all patients. rGFR was repeated to evaluate the renal outcome at 4 months after PTRAS. The outcome of PTRAS was classified as improved, stable, or deteriorated compared to the baseline. Time-intensity curve (TIC) parameters obtained from CEUS were analyzed to evaluate the predictive accuracy.

Results

TIC parameters (AUC and PI) were positively correlated with renal function (r=0.617, 0.663; P<0.05) but weakly and negatively correlated with the stenosis (r=−0.360, −0.435; P<0.05). Baseline rGFR was not accurate in predicting improved renal function after PTRAS (0.670). The accuracy of the combined prediction model of baseline AUC and PI (0.889) was higher than the individual indicators (baseline AUC: 0.855 and PI: 0.782).

Conclusion

CEUS could accurately assess renal parenchymal perfusion and identify ARAS patients with potential benefit after PTRAS. The combination of TIC parameters (AUC and PI) is valuable in the prediction of improved renal function after PTRAS.

Renal Artery Stenosis in the Patient with Hypertension: Prevalence, Impact and Management

Atherosclerosis is the primary cause of renal artery stenosis. Atherosclerotic renal artery stenosis (ARAS) is associated with three clinical problems: renovascular hypertension, ischemic nephropathy and cardiac destabilization syndrome which pose huge healthcare implications. There is a significant rate of natural disease progression with worsening severity of renal artery stenosis when renal revascularization is not pursued in a timely manner. Selective sub-groups of individuals with ARAS have had good outcomes after percutaneous renal artery stenting (PTRAS). For example, individuals that underwent PTRAS and had improved renal function were reported to have a 45% survival advantage compared to those without improvement in their renal function. Advances in the imaging tools have allowed for better anatomic and physiologic measurements of ARAS. Measuring translesional hemodynamic gradients has allowed for accurate assessment of ARAS severity. Renal revascularization with PTRAS provides a survival advantage in individuals with significant hemodynamic renal artery stenosis lesions. It is important that we screen, diagnosis, intervene with invasive and medical treatments appropriately in these high-risk patients.

Current Concepts in the Treatment of Renovascular Hypertension

Renovascular disease (RVD) remains a major cause of secondary and treatment-resistant hypertension. Most cases are related either to fibromuscular or atherosclerotic lesions, but a variety of other causes including arterial dissection, stent occlusion, and embolic disease can produce the same syndrome. Recent studies emphasize the kidney's tolerance to moderate flow reduction during antihypertensive drug therapy and the relative safety of medical therapy to control blood pressure. Several prospective trials in moderate RVD fail to identify major benefits from endovascular revascularization for moderate atherosclerotic disease. However, high-risk and progressive renovascular syndromes are recognized to be relatively refractory to medical therapy only and respond better to combining renal revascularization with ongoing medical therapy. Clinicians caring for complex hypertension should be familiar with pathogenic pathways, imaging techniques, and a rational approach to managing renovascular hypertension in the current era.

Primary Prevention of Stroke in Chronic Kidney Disease Patients: A Scientific Update

BACKGROUND

Although chronic kidney disease (CKD) is an independent risk factor for stroke, official recommendations for the primary prevention of stroke in CKD are generally lacking.

SUMMARY

We searched PubMed and ISI Web of Science for randomised controlled trials, observational studies, reviews, meta-analyses and guidelines referring to measures of stroke prevention or to the treatment of stroke-associated risk factors (cardiovascular disease in general and atrial fibrillation (AF), arterial hypertension or carotid artery disease in particular) among the CKD population. The use of oral anticoagulation in AF appears safe in non-end stage CKD, but it should be individualized and preferably based on thromboembolic and bleeding stratification algorithms. Non-vitamin K antagonist oral anticoagulants with definite dose adjustment are generally preferred over vitamin K antagonists in mild and moderate CKD and their indications have started being extended to severe CKD and dialysis also. Aspirin, but not clopidogrel, has limited indications for reducing the risk for atherothrombotic events in CKD due to its increased bleeding risk. Carotid endarterectomy has shown promising results for stroke risk reduction in CKD patients with high-grade symptomatic carotid stenosis. The medical treatment of arterial hypertension in CKD often fails to efficiently lower blood pressure values, but recent data regarding the use of interventional procedures such as renal denervation, baroreflex activation therapy or renal artery stenting are encouraging. Key Messages: In the absence of clear guidelines and protocols, primary prevention of stroke in CKD patients remains a subtle art in the hands of the clinicians. Nevertheless, refraining CKD patients from standard therapies often worsens their prognosis.

Atherosclerotic renovascular disease - epidemiology, treatment and current challenges

The neutral results of recent large randomized controlled trials comparing renal revascularization with optimal medical therapy in patients with atherosclerotic renovascular disease (ARVD) have cast doubt on the role of revascularization in the management of unselected patients with this condition. However, these studies have strengthened the evidence base for the role of contemporary intensive medical vascular protection therapy and aggressive risk factor control in improving clinical outcomes in ARVD. Patients presenting with ‘high-risk’ clinical features such as uncontrolled hypertension, rapidly declining renal function or flash pulmonary oedema are underrepresented in these studies; hence these results may not be applicable to all patients with ARVD. In this ‘high-risk’ subgroup, conservative management may not be sufficient in preventing adverse events, and indeed, observational evidence suggests that this specific patient subgroup may gain benefit from timely renal revascularization. Current challenges include the development of novel diagnostic techniques to establish haemodynamic significance of a stenosis, patient risk stratification and prediction of post-revascularization outcomes to ultimately facilitate patient selection for revascularization. In this paper we describe the epidemiology of this condition and discuss treatment recommendations for this condition in light of the results of recent randomized controlled trials while highlighting important clinical unmet needs and challenges faced by clinicians managing this condition.

Kidney volume to GFR ratio predicts functional improvement after revascularization in atheromatous renal artery stenosis

BACKGROUND

Randomized controlled trials (RCT) have shown no overall benefit of renal revascularization in atherosclerotic renovascular disease (ARVD). However, 25% of patients demonstrate improvement in renal function. We used the ratio of magnetic resonance parenchymal volume (PV) to isotopic single kidney glomerular filtration rate (isoSKGFR) ratio as our method to prospectively identify "improvers" before revascularization.

METHODS

Patients with renal artery stenosis who were due revascularization were recruited alongside non-ARVD hypertensive CKD controls. Using the controls, 95% CI were calculated for expected PV:isoSK-GFR at given renal volumes. For ARVD patients, "improvers" were defined as having both >15% and >1ml/min increase in isoSK-GFR at 4 months after revascularization. Sensitivity and specificity of PV:isoSK-GFR for predicting improvers was calculated.

RESULTS

30 patients (mean age 68 ±8 years), underwent revascularization, of whom 10 patients had intervention for bilateral RAS. Stented kidneys which manifested >15% improvement in function had larger PV:isoSK-GFR compared to controls (19±16 vs. 6±4ml/ml/min, p = 0.002). The sensitivity and specificity of this equation in predicting a positive renal functional outcome were 64% and 88% respectively. Use of PV:isoSK-GFR increased prediction of functional improvement (area under curve 0.93). Of note, non-RAS contralateral kidneys which improved (n = 5) also demonstrated larger PV:isoSK-GFR (15.2±16.2 ml/ml/min, p = 0.006).

CONCLUSION

This study offers early indicators that the ratio of PV:isoSK-GFR may help identify patients with kidneys suitable for renal revascularization which could improve patient selection for a procedure associated with risks. Calculation of the PV:isoSK-GFR ratio is easy, does not require MRI contrast agent.

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.

Renal Arterial Disease and Hypertension

Renal artery disease produces a spectrum of progressive clinical manifestations ranging from minor degrees of hypertension to circulatory congestion and kidney failure. Moderate reductions in renal blood flow do not induce tissue hypoxia or damage, making medical therapy for renovascular hypertension feasible. Several prospective trials indicate that optimized medical therapy using agents that block the renin-angiotensin system should be the initial management. Evidence of progressive disease and/or treatment failure should allow recognition of high-risk subsets that benefit from renal revascularization. Severe reductions in kidney blood flow ultimately activate inflammatory pathways that do not reverse with restoring blood flow alone.

Renal artery stent in solitary functioning kidneys: 77% of benefit: A systematic review with meta-analysis

BACKGROUND

Solitary functioning kidney (SFK) is tough issue to address in clinical, mostly developed from renal artery stenosis (RAS) in adults. Although renal artery stent is widely used to help SFK patients, the efficacy of the stent is still disputable. This study is aimed at reviewing a series of SFK cases to draw a conclusion about the efficacy of renal artery stent.

METHODS

All related papers published in PubMed, Web of Science, EMBASE, and Cochrane Library were searched. Studies or subsets were included only if they satisfied certain criteria. The benefit rate which equaled the rate of improvement subjoining the rate of stabilization was calculated. All analyses were conducted with Stata version 12.0 (Stata Corporation, College Station, TX).

RESULTS

According to 7 papers on the efficacy of renal artery stent, 253 SFK patients were included. The result revealed that the renal artery stent could help SFK patients to improve or stabilize their renal function (RF). The benefit rate was 0.77, with 95% confidence interval between 0.72 and 0.83.

CONCLUSIONS

With proper patient selection, renal artery stent could benefit SFK patients with a percentage odd of 0.77 to improve or stabilize the RF.

To Stent or Not to Stent? Update on Revascularization for Atherosclerotic Renovascular Disease

Renal artery stenosis (RAS) is increasingly encountered in clinical practice. The two most common etiologies are fibromuscular dysplasia (FMD) and atherosclerotic renal artery disease (ARAS), with the latter accounting for the vast majority of cases. Significant RAS activates the renin-angiotensin-aldosterone system and is associated with three major clinical syndromes: ischemic nephropathy, hypertension, and destabilizing cardiac syndromes. Over the past two decades, advancements in diagnostic and interventional techniques have led to improved detection and the widespread use of endovascular renal artery revascularization strategies in the management of ARAS. However, renal artery stenting for ARAS remains controversial. Although several studies have demonstrated some benefit with renal artery revascularization, this has not been to the extent anticipated or predicted. Moreover, these trials have significant flaws in their study design and are hampered with inherent bias which make their interpretation challenging. In this review, we evaluate the existing body of evidence and offer an approach to the management of patients with ARAS in light of the current literature. From the data provided, identification of subgroup of patients, namely, those with a hemodynamically significant RAS in the context of progressive renal insufficiency and/or deteriorating arterial hypertension, seems possible and may derive clinical benefit from ARAS stent revascularization. Appropriate patient selection is therefore the key and more robust studies are required.

Update on intervention versus medical therapy for atherosclerotic renal artery stenosis

Atherosclerotic renal artery stenosis is known to be one of the most common causes of secondary hypertension, and early nonrandomized studies suggested that renal artery stenting (RASt) improved outcomes. The vascular community embraced this less invasive treatment alternative to surgery, and RASt increased in popularity during the late 1990s. However, recent randomized studies have failed to show a benefit regarding blood pressure or renal function when RASt was compared with best medical therapy, creating significant concerns about procedural efficacy. In the wake of these randomized trial results, hypertension and renal disease experts along with vascular interventional specialists now struggle with how to best manage atherosclerotic renal artery stenosis. This review objectively analyzes the current literature and highlights each trial's design weaknesses and strengths. We have provided our recommendations for contemporary treatment guidelines based on our interpretation of the available empirical data.

Management of atherosclerotic renovascular disease after Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL)

Many patients with occlusive atherosclerotic renovascular disease (ARVD) may be managed effectively with medical therapy for several years without endovascular stenting, as demonstrated by randomized, prospective trials including the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial, the Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) trial and the Stent Placement and Blood Pressure and Lipid-Lowering for the Prevention of Progression of Renal Dysfunction Caused by Atherosclerotic Ostial Stenosis of the Renal Artery (STAR) and ASTRAL. These trials share the limitation of excluding subsets of patients with high-risk clinical presentations, including episodic pulmonary edema and rapidly progressing renal failure and hypertension. Although hemodynamically significant, ARVD can reduce renal blood flow and glomerular filtration rate; adaptive mechanisms preserve both cortical and medullary oxygenation over a wide range of vascular occlusion. Progression of ARVD to severe vascular compromise eventually produces cortical hypoxia, however, associated with active inflammatory cytokine release and cellular infiltration of the renal parenchyma. In such cases ARVD produces a loss of glomerular filtration rate that no longer is reversible simply by restoring vessel patency with technically successful renal revascularization. Each of these trials reported adverse renal functional outcomes ranging between 16 and 22% over periods of 2-5 years of follow-up. Blood pressure control and medication adjustment may become more difficult with declining renal function and may prevent the use of angiotensin receptor blocker and angiotensin-converting enzyme inhibitors. The objective of this review is to evaluate the current management of ARVD for clinical nephrologists in the context of recent randomized clinical trials and experimental research.

Reversible dialysis-dependent renal failure due to undiagnosed renovascular disease

Renovascular disease (RVD) can present with resistant hypertension, acute or rapidly progressive renal failure and occasionally nephrotic proteinuria. Revascularization plays an important role in controlling blood pressure and preserving renal function. It is widely believed that delay in revascularization would result in irreversible loss of renal function. However, we report a favorable outcome despite delayed revascularization in two patients of RVD- one presenting with recurrent flash pulmonary edema and other with progressive renal failure. The former's serum creatinine returned to normal despite 3 months of anuria and the latter became dialysis-independent despite 2 months of progressive decline in renal function. Both remain dialysis-free 3 years after surgery.

Percutaneous revascularization for ischemic nephropathy: the past, present, and future

Occlusion of the renal arteries can threaten the viability of the kidney when severe, in addition to accelerating hypertension and circulatory congestion. Renal artery stenting procedures have evolved from a treatment mainly for renovascular hypertension to a maneuver capable of recovering threatened renal function in patients with “ischemic nephropathy” and improving management of congestive heart failure. Improved catheter design and techniques have reduced, but not eliminated hazards associated with renovascular stenting. Expanded use of endovascular stent grafts to treat abdominal aortic aneurysms has introduced a new indication for renal artery stenting to protect the renal circulation when grafts cross the origins of the renal arteries. Although controversial, prospective randomized trials to evaluate the added benefit of revascularization to current medical therapy for atherosclerotic renal artery stenosis until now have failed to identify major benefits regarding either renal function or blood pressure control. These studies have been limited by selection bias and have been harshly criticized. While studies of tissue oxygenation using blood oxygen level dependent (BOLD) MR establish that kidneys can adapt to reduced blood flow to some degree, more severe occlusive disease leads to cortical hypoxia associated with microvascular rarefication, inflammatory injury and fibrosis. Current research is directed toward identifying pathways of irreversible kidney injury due to vascular occlusion and to increase the potential for renal repair after restoring renal artery patency. The role of nephrologists likely will focus upon recognizing the limits of renal adaptation to vascular disease and identifying kidneys truly at risk for ischemic injury at a time point when renal revascularization can still be of benefit to recovering kidney function.

Renal intervention to treat hypertension

Renal artery intervention to treat hypertension is one of the frontiers of ongoing research in combating this epidemic. This article focuses on recent data regarding PTRS and catheter-based renal sympathetic denervation. Despite progress in this field large multicenter, randomized trials that compare these treatment modalities with medical therapy for hypertension are lacking.

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.