The “Chicken Little” of Renal Stent Trials: The CORAL Trial in Perspective

How should we define appropriate patients for percutaneous transluminal renal angioplasty treatment?

Renovascular hypertension (RVH) is one of the most common causes of secondary hypertension and can result in resistant hypertension. RVH is associated with an increased risk for progressive decline in renal function, cardiac destabilization syndromes including "flash" pulmonary edema, recurrent congestive heart failure, and cerebrocardiovascular disease. The most common cause of renal artery stenosis (RAS) is atherosclerotic lesions, followed by fibromuscular dysplasia. The endovascular technique of percutaneous transluminal renal angioplasty (PTRA) with or without stenting is one of the standard treatments for RAS. Randomized controlled trials comparing medical therapy with PTRA to medical therapy alone have failed to show a benefit of PTRA; however, the subjects of these randomized clinical trials were limited to atherosclerotic RAS patients, and patients with the most severe RAS, who would be more likely to benefit from PTRA, might not have been enrolled in these trials. This review compares international guidelines related to PTRA, reevaluates the effects of PTRA treatment on blood pressure and renal and cardiac function, discusses strategies for the management of RVH patients, and identifies factors that may predict which patients are most likely to benefit from PTRA.

[Can the pre-dialysis period in stage IV chronic kidney disease be prolonged?]

Analysed herein are the results of treating a total of 29 patients presenting with stage IV chronic kidney disease (CKD) induced by ischaemic nephropathy. All patients had renal artery stenosis more than 80%, decreased glomerular filtration rate (GFR) below 30 ml/min/1.73m2 and were regarded by the nephrologists as potential candidates for programmed haemodialysis. After preparation aimed at preventing contrast-induced nephropathy all patients underwent stenting of the stenosed renal arteries. In the early postoperative period, 21 patients were found to have stabilization of the GFR with a tendency to increase. One woman developed acute renal failure requiring renal replacement therapy by means of haemodialysis. During the follow-up period from 1 to 5 years, 26 patients showed no progression of azotemia. CKD changed to stage III in 15 patients (p<0.005). Twenty-three (84%) patients during the follow-up period developed no new cardiovascular events. Hence, performing renal revascularization for renal artery stenosis >80% revealed in patients with stage IV CKD promotes prolongation of the dialysis-free period.

Factors Associated with Outcomes of Percutaneous Transluminal Renal Angioplasty in Patients with Renal Artery Stenosis: A Retrospective Analysis of 50 Consecutive Cases

Background

The results of recent trials have brought some confusion to the treatment strategy for renal artery stenosis (RAS). To evaluate the applicability of percutaneous transluminal renal angioplasty (PTRA) for RAS, we extracted the factors that may affect the effectiveness of PTRA from cases experienced at a hypertension center.

Methods and Results

We retrospectively assessed the blood pressure (BP) lowering effects and renoprotective effects in 50 consecutive patients that had hemodynamically significant RAS and had undergone PTRA and stenting during 2001–2005. Subjects were diagnosed with atherosclerotic RAS (42), fibromuscular dysplasia (6), or Takayasu disease (2). After PTRA, BP significantly lowered from 152.3/80.3 mmHg to 132.6/73.2 mmHg (p < 0.05), but the estimated glomerular filtration rate (eGFR) did not change significantly. There were no factors associated with the BP lowering effects of PTRA. The baseline resistive index (RI) was negatively correlated with the change in eGFR (p < 0.05). After correction for age, sex, BMI, and the dose of contrast medium, the association of RI with change in eGFR remained significant.

Conclusion

In cases with hemodynamically significant RAS, PTRA lowered BP but was not effective in improving renal function. Higher baseline RI may be a factor for predicting poor clinical course of renal function after PTRA.

Predictors of cardiac benefits of renal artery stenting from a multicentre retrospective registry

OBJECTIVES

There have been limited data regarding the prediction of cardiac benefits after renal artery stenting for patients with atherosclerotic renal artery disease (ARAD). The aim of this multicentre retrospective study was to identify clinical or echocardiographic factors associated with improvements of cardiac symptoms after renal artery stenting.

METHODS

We enrolled 58 patients with de novo ARAD undergoing successful renal artery stenting for heart failure, angina or both between January 2000 and August 2015 at 13 hospitals.

RESULTS

Improvement of cardiac symptoms was observed in 86.2% of patients during a mean follow-up of 6.0±2.7 months. Responders demonstrated significantly lower New York Heart Association functional class, higher estimated glomerular filtration rate, lower serum creatinine and lower interventricular septal wall thickness (IVS), lower left ventricular mass index, lower left atrial dimension and lower E-velocity than non-responders. Backward stepwise multivariate analysis identified IVS as an independent predictor of improvement of cardiac symptoms (OR 0.451, 95% CI 0.209 to 0.976; p=0.043). According to receiver operating characteristic curve analysis, an IVS cut-off of 11.9 mm provided the best predictive value, with sensitivity of 71.4%, specificity of 75.5% and accuracy of 73.5%. The positive predictive value was 74.5% and the negative predictive value was 72.5%.

CONCLUSIONS

This multicentre retrospective study shows that the echocardiographic index of IVS is an independent predictor for improvement of cardiac symptoms after renal artery stenting.

Renal artery stenosis: if and when to intervene

PURPOSE OF REVIEW

Atherosclerotic renovascular disease remains highly prevalent and presents an array of clinical syndromes. Recent prospective trials have dampened enthusiasm for revascularization generally, but clinicians recognize the need to identify patients likely to benefit from vascular intervention.

RECENT FINDINGS

This article highlights the inflammatory nature of vascular occlusive disease and the limits of the kidney to adapt to reduced blood flow. Although moderate reductions can be tolerated, severe impairment of renal perfusion leads to tissue hypoxia and activates inflammatory injury within the kidney. Hence, assessment of kidney viability and potential tools to modify mitochondrial and inflammatory damage may be important to identify patients for whom clinical intervention should be undertaken.

SUMMARY

Clinicians must recognize clinical syndromes that identify 'high-risk' groups and apply revascularization in those likely to benefit. Future efforts to protect the kidney (e.g., mitochondrial protection) or cell-based therapy may amplify clinical recovery when combined with restoring renal blood flow.

Treatment of In-Stent Restenosis in Patients with Renal Artery Stenosis

PURPOSE

To determine clinical outcomes of patients treated for renal artery in-stent restenosis (ISR) with atherosclerotic renal artery stenosis.

MATERIALS AND METHODS

A retrospective review was performed of the clinical data of all patients who underwent renal artery stent placement for atherosclerotic renal artery stenosis from 1996 to 2009. Medical records of patients were reviewed for relevant clinical history, including blood pressure, antihypertensive medications, and renal function data before and after an intervention. In 1,052 patients, 1,090 renal artery stent placements were performed. Of these, 101 stents in 79 patients developed ISR, which was treated with either percutaneous transluminal angioplasty (PTA) or repeat stent placement. Procedural details, including modality of intervention, stent diameter, and time to restenosis, were recorded. Hypertensive agent and use of statins were recorded. Univariate analysis was performed to identify risk factors associated with restenosis after treatment of ISR.

RESULTS

Patients treated with repeat stent placement were 6.89 times more likely to lose patency after treatment than patients treated with PTA (P < .01). No additional clinical or procedural factor, including smoking history; presence of cardiac, renal, or metabolic disease; use of statin at time of ISR treatment; or diameter of treatment (stent or PTA), had a significant association with duration of stent or angioplasty patency.

CONCLUSIONS

Treatment of renal artery ISR with PTA among patients with atherosclerotic renal artery stenosis has a lower rate of subsequent ISR compared with repeat stent placement.

Renovascular heart failure: heart failure in patients with atherosclerotic renal artery disease

Atherosclerotic renal artery disease presents with a broad spectrum of clinical features, including heart failure as well as hypertension, and renal failure. Although recent randomized controlled trials failed to demonstrate renal artery stenting can reduce blood pressure or the number of cardiovascular or renal events more so than medical therapy, increasing attention has been paid to flash pulmonary edema and congestive heart failure associated with atherosclerotic renal artery disease. This clinical entity "renovascular heart failure" is diagnosed retrospectively. Given the increasing global burden of heart failure, this review highlights the background and catheter-based therapeutic aspects for renovascular heart failure.

Atherosclerotic renal artery stenosis and revascularization

Atherosclerotic renovascular disease is the most common cause of secondary hypertension. The patients with renovascular disease are at increased risk for adverse cardiac outcomes. Recent trials comparing medical therapy alone to medical therapy with stenting are flawed, but lay to rest any existing debate that unselected revascularization is unwarranted; however, revascularization may be appropriate in high-risk populations. Defining an appropriate population for revascularization is an area of ongoing study. Furthermore, delivery of optimal medical therapy in this population is inadequate. This review describes recent developments in renal artery revascularization.

Management of Renal Arterial Disease

Severe atherosclerotic renal artery stenosis can manifest as treatment-resistant hypertension, ischemic nephropathy and/or cardiac disturbance syndromes of recurrent flash pulmonary edema and refractory angina. Renal artery revascularization can dramatically impact patient outcome. However, patient selection for revascularization can be challenging. Renal artery stenting is most commonly used for renal revascularization and is a safe procedure when performed in carefully selected patients. This review addresses the pathophysiology of renal artery stenosis and the data supporting revascularization in such patients.