Renovascular disease: effect of ACE gene deletion polymorphism and endovascular revascularization

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.

Renal artery stenosis - an update

Renal artery stenosis (RAS) is a common form of peripheral arterial disease. The most common cause of RAS is atherosclerosis. It is predominantly unilateral. The pathophysiologic mechanism stems from renal underperfusion resulting in the activation of the renin- angiotensin-aldosterone pathway. Even though the majority of patients with RAS are asymptomatic, it can clinically present with hypertension, nephropathy and congestive heart failure. This progressive disease can lead to resistant hypertension and end stage kidney failure. Screening patients for RAS with either Doppler ultrasonography, computed tomographic angiography, or magnetic resonance angiography is preferred. Adequate blood pressure control, goal-directed lipid-lowering therapy, smoking cessation, and other preventive measures form the foundation of management of patients with RAS. Catheter-based percutaneous revascularization with angioplasty and stenting showed modest clinical benefit for patients in small retrospective studies, but data from randomized clinical trials failed to confirm these beneficial results. The current ongoing Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial may provide more concrete data regarding the role of stenting in RAS. Surgical revascularization is considered only if catheter-based revascularization is unsuitable or unsuccessful. The American College of Cardiology/American Heart Association guidelines on evaluation and management of patients with RAS provide the framework for determining individualized assessment and treatment plans for patients with RAS.

Efficacy of percutaneous transluminal renal angioplasty with stent in elderly male patients with atherosclerotic renal artery stenosis

OBJECTIVES

Percutaneous transluminal renal angioplasty with stent implantation (PTRAS) has become the treatment of choice for atherosclerotic renal artery stenosis (ARAS). This study evaluates the long-term effects of PTRAS on hypertension and renal function in elderly patients with ARAS.

METHODS

We conducted a retrospective cohort study of all patients who underwent PTRAS in the geriatric division of a tertiary medical center during the period 2003-2010. The clinical data were extracted from the medical records of each patient. Changes in blood pressure, antihypertensive treatment, and estimated glomerular filtration rate were analyzed before and after PTRAS.

RESULTS

Eighty-six stents in 81 elderly patients were placed successfully. The average age of the patients was 76.2 years (65-89 years). Mean follow-up was 31.3 months (range 12 -49 months). There was a significant decrease in both systolic and diastolic blood pressure at the third day after the PTRAS procedure and the reduction in blood pressure was constant throughout the follow-up period until 36 months after PTRAS. However, there was no marked benefit to renal function outcome during the follow-up period. The incidence of contrast-induced nephropathy was 9.9% in this study group. The rate of renal artery restenosis was 14.8%. The survival rate was 96.3% for 4 years after the procedure.

CONCLUSION

It is beneficial to control blood pressure in elderly patients with ARAS up to 36 months after a PTRAS procedure. However, their renal function improvement is limited.

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.

Clinical practice. Renal-artery stenosis

A 73-year-old former smoker with a history of hypertension and dyslipidemia presents to the emergency department with shortness of breath. His blood pressure is 160/75 mm Hg, heart rate 60 beats per minute, and respiratory rate 24 breaths per minute. Chest auscultation reveals diffuse rales, and there is 1+ pitting edema. The serum creatinine level is 1.4 mg per deciliter (124 µmol per liter) (estimated glomerular filtration rate, 52 ml per minute), and urinalysis shows 1+ protein. His condition improves after treatment with intravenous diuretics, but his systolic blood pressure remains elevated, at 170 mm Hg. Magnetic resonance angiography (MRA) reveals a diseased aorta, a high-grade ostial lesion of the left renal artery that is consistent with atherosclerotic stenosis, and a normal right renal artery. How should he be further evaluated and treated?

The role of percutaneous revascularization for renal artery stenosis

Renal artery stenosis (RAS) is usually caused by atherosclerosis or fibromuscular dysplasia. RAS leads to activation of the renin-angiotensin-aldosterone system and may result in hypertension, ischemic nephropathy, left ventricular hypertrophy and congestive heart failure. Management options include medical therapy and revascularization procedures. Recent studies have shown angiotensin receptor blockers (ARB) and angiotensin converting enzyme inhibitors (ACE-I) to be highly effective in treating the hypertension associated with RAS and in reducing cardiovascular events; however, they do not correct the underlying RAS and loss of renal mass may continue. Renal artery angioplasty was first performed by Gruntzig in 1978. The routine use of stents has increased technical success rates compared with angioplasty, and surgery is now only rarely performed. Although numerous case series claimed benefit in terms of blood pressure control, no adequately powered randomized, controlled, prospective study of renal artery interventions has reported their effect on cardiovascular morbidity or mortality. The CORAL trial, an ongoing study of renal artery stent placement and optimal medical therapy (OMT) funded by the National Institutes of Health, is the first study to attempt to do so. Until the CORAL trial results are in, physicians will continue to be faced with difficult choices when determining the optimal management for RAS patients and deciding which, if any, patients should be offered revascularization.

Stent revascularization for the prevention of cardiovascular and renal events among patients with renal artery stenosis and systolic hypertension: rationale and design of the CORAL trial

BACKGROUND

Atherosclerotic renal artery stenosis is a problem with no consensus on diagnosis or therapy. The consequences of renal ischemia are neuroendocrine activation, hypertension, and renal insufficiency that can potentially result in acceleration of atherosclerosis, further renal dysfunction, myocardial infarction, heart failure, stroke, and death. Whether revascularization improves clinical outcomes when compared with optimum medical therapy is unknown.

METHODS

CORAL is a randomized clinical trial contrasting optimum medical therapy alone to stenting with optimum medical therapy on a composite cardiovascular and renal end point: cardiovascular or renal death, myocardial infarction, hospitalization for congestive heart failure, stroke, doubling of serum creatinine, and need for renal replacement therapy. The secondary end points evaluate the effectiveness of revascularization in important subgroups of patients and with respect to all-cause mortality, kidney function, renal artery patency, microvascular renal function, and blood pressure control. We will also correlate stenosis severity with longitudinal renal function and determine the value of stenting from the perspectives of quality of life and cost-effectiveness. The primary entry criteria are (1) an atherosclerotic renal stenosis of > or = 60% with a 20 mm Hg systolic pressure gradient or > or = 80% with no gradient necessary and (2) systolic hypertension of > or = 155 mm Hg on > or = 2 antihypertensive medications. Randomization will occur in 1080 subjects. The study has 90% power to detect a 28% reduction in primary end point hazard rate.

CONCLUSIONS

CORAL represents a unique opportunity to determine the incremental value of stent revascularization, in addition to optimal medical therapy, for the treatment of atherosclerotic renal artery stenosis.

Predictive Factors of In-Stent Restenosis in Renal Artery Stenting: A Retrospective Analysis

PURPOSE

To retrospectively evaluate the role of clinical and procedural factors in predicting in-stent restenosis in patients with renovascular disease treated by renal artery stenting.

METHODS

From 1995 to 2002, 147 patients underwent renal artery stenting for the treatment of significant ostial atherosclerotic stenosis. Patients underwent strict clinical and color-coded duplex ultrasound follow-up. Ninety-nine patients (111 stents), with over 6 months of continuous follow-up (mean 22+/-12 months, range 6-60 months), were selected and classified according to the presence (group A, 30 patients, 32 lesions) or absence (group B, 69 patients, 79 lesions) of significant in-stent restenosis. A statistical analysis was performed to identify possible preprocedural and procedural predictors of restenosis considering the following data: sex, age, smoking habit, diabetes mellitus, hypertension, serum creatinine, cholesterol and triglyceride levels, renal artery stenosis grade, and stent type, length and diameter.

RESULTS

Comparing group A and B patients (chi(2) test), a statistically significant relation was demonstrated between stent diameter and length and restenosis: the risk of in-stent restenosis decreased when the stent was >/=6 mm in diameter and between 15 and 20 mm in length. This finding was confirmed by multiple logistic regression analysis. Stent diameter and length were proved to be significantly related to in-stent restenosis also when evaluating only patients treated by Palmaz stent (71 stents).

CONCLUSION

Although it is based on a retrospective analysis, the present study confirms the importance of correct stent selection in increasing long-term patency, using stents of at least 6 mm in diameter and with a length of approximately 15-20 mm.

Current endovascular management of atherosclerotic renal artery stenosis

The recent advances in stent technology and renal endovascular management have provided a technically reproducible method of percutaneously treating atherosclerotic renal artery stenosis (RAS). In many centers, this has resulted in endovascular management being the primary therapy for atherosclerotic RAS. Although still controversial, it appears that endovascular management of RAS by primay stent deployment provides better blood pressure control than that afforded by best medical management. The impact on renal function is less than that found for hypertension, but there is evidence to suggest that the use of protection devices and primary stenting may enhance renal function outcomes. Whether the ultimate benefit of enhanced survival follows remains an important question and should be the subject of future prospective studies.