Prospective evaluation of aggressive medical therapy for atherosclerotic renal artery stenosis, with renal artery stenting reserved for previously injured heart, brain, or kidney

Outcomes after stenting of renal artery stenosis in patients with high-risk clinical features

BACKGROUND

In patients with renal artery stenosis, revascularization was seen as a mean to improve outcomes, but large studies failed to show significant benefit in general population. However, data on benefits of renal artery stenting in patients with high-risk features, such as rapidly declining renal function and cardiac destabilization syndromes, are limited, as they were excluded from trials. In this descriptive study, we aimed to evaluate short- and long-term outcomes in high-risk patients with renal artery stenosis, treated by angioplasty and stenting. We have retrospectively interrogated our local databases for renal artery percutaneous interventions; patients at high-risk (rapidly declining renal function; stable chronic renal failure and bilateral renal artery disease; severe hypertensive crisis) were selected for the current analysis.

RESULTS

Of 30 patients undergoing renal artery stenting, 18 patients were deemed "high-risk." On short term, good in-hospital control of hypertension and cardiac stabilization were obtained in all patients. Renal function improved significantly only in patients admitted with rapidly declining renal function, with significant creatinine level fall from median 3.98 mg/dL to 2.02 mg/dL, p = 0.023. However, for the whole group, creatinine change was non-significant (- 0.12 mg/dL, p = NS). On the long term, five patients (27.8%) ended-up on chronic hemodialysis and six patients died (33.3%) after a median of 20 months. No death occurred during the first year after the procedure.

CONCLUSIONS

Percutaneous procedures are feasible and safe in patients with high-risk renal artery stenosis, especially in those with rapidly declining renal function, probably saving some of them from the immediate need for renal replacement therapy, but long-term results are negatively influenced by the precarious general and cardio-vascular status of these patients and by the pre-existing significant renal parenchymal disease, non-related to the renal artery stenosis.

Renal artery stenosis

Renal artery stenosis is the most common secondary cause of hypertension and predominantly caused by atherosclerosis. In suspected patients, a non-invasive diagnosis with ultrasound is preferred. Asymptomatic, incidentally found RAS does not require revascularization. In symptomatic patients requiring revascularization, renal artery stenting is the preferred therapy. Selecting appropriate patients for revascularization requires careful consideration of lesion severity and is optimized with a multidisciplinary team. All patients with atherosclerotic RAS should be treated with guideline-directed medical therapy, including hypertension control, diabetes control, statins, antiplatelet therapy, smoking cessation and encouraging activity.

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.

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.

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.

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 process, renovascular disease and outcomes from bench to bedside

PURPOSE OF REVIEW

Atherosclerotic renal artery stenosis has become an important cause of secondary hypertension and renal dysfunction in the aging population. Its presence increases cardiovascular morbidity and mortality independent of other atherosclerotic risk factors. Therefore, novel renoprotective strategies are needed to decrease the impact of this disease.

RECENT FINDINGS

Although medical therapy can be effective in patients with atherosclerotic renal artery stenosis and mild renal dysfunction, revascularization is desirable for patients with target-organ injury. Technical developments (such as drug-eluting or low-profile stents and distal protection devices) have increased the safety and effectiveness of renal revascularization, but in a significant proportion of patients renal function is not fully restored. Recent experimental evidence suggests that atherosclerotic renal artery stenosis is associated with the activation of intrarenal fibrogenic and inflammatory pathways, oxidative stress, and microvascular remodeling, and blocking these mechanisms can improve renal hemodynamics and function.

SUMMARY

Despite significant advances in revascularization techniques, it remains unclear why the kidney affected by atherosclerotic renal artery stenosis often does not improve or even progressively deteriorates. In addition to the restoration of blood flow, targeted interventions to attenuate injurious intrarenal mechanisms should probably become part of a comprehensive management plan to preserve the ischemic kidney.

Clinical insights into the diagnosis and management of atherosclerotic renal artery disease

Atherosclerotic renovascular disease (ARVD) is an increasingly common contributor to hypertension and renal failure. However, not all patients with an identified obstructive atherosclerotic renal artery stenosis will have clinical improvement, even after successful percutaneous intervention. As such, there remains extensive controversy regarding optimal diagnostic and treatment strategies. Part of this controversy is the result of a paucity of well-designed prospective, randomized clinical trials, but the complex nature of the disorder and the heterogeneity of patients presenting with possible ARVD make simple diagnostic and treatment paradigms difficult to develop. This narrative review describes the latest observations concerning the prevalence, pathogenesis, natural history, diagnostic studies, and treatment options for suspected ARVD. Hopefully, this knowledge will improve the ability of clinicians to weigh risks and benefits and determine the best strategy in individual patients.