and Reinhart T. Grundmann2
(1)
Department of Vascular Medicine, University Heart and Vascular Center at University Clinics Hamburg–Eppendorf, Hamburg, Germany
(2)
Former Medical Director, Community Hospital Altoetting-Burghausen, Burghausen, Germany
5.1 Guidelines
5.1.1 American College of Cardiology Foundation/American Heart Association
For diagnostic studies to identify clinically significant renal artery stenosis (RAS) the following Class I recommendations are given (Anderson et al. 2013):
- 1.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with the onset of hypertension before the age of 30 years (Level of Evidence: B).
- 2.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with the onset of severe hypertension after the age of 55 years (Level of Evidence: B).
- 3.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with the following characteristics: (a) accelerated hypertension (sudden and persistent worsening of previously controlled hypertension); (b) resistant hypertension (defined as the failure to achieve goal blood pressure in patients who are adhering to full doses of an appropriate 3-drug regimen that includes a diuretic); or (c) malignant hypertension (hypertension with coexistent evidence of acute end-organ damage, i.e., acute renal failure, acutely decompensated congestive heart failure, new visual or neurological disturbance, and/or advanced [grade III to IV] retinopathy) (Level of Evidence: C).
- 4.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with new azotemia or worsening renal function after the administration of an ACE inhibitor or an angiotensin receptor blocking agent (Level of Evidence: B).
- 5.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with an unexplained atrophic kidney or a discrepancy in size between the two kidneys of greater than 1.5 cm (Level of Evidence: B).
- 6.
The performance of diagnostic studies to identify clinically significant RAS is indicated in patients with sudden, unexplained pulmonary edema (especially in azotemic patients) (Level of Evidence: B).
For renal revascularization these guidelines recommend:
Asymptomatic Stenosis:
- 1.
Percutaneous revascularization may be considered for treatment of an asymptomatic bilateral or solitary viable kidney with a hemodynamically significant RAS (Class IIb recommendation/Level of Evidence: C).
- 2.
The usefulness of percutaneous revascularization of an asymptomatic unilateral hemodynamically significant RAS in a viable kidney is not well established and is presently clinically unproven (Class IIb recommendation/Level of Evidence: C).
Hypertension:
- 1.
Percutaneous revascularization is reasonable for patients with hemodynamically significant RAS and accelerated hypertension, resistant hypertension, malignant hypertension, hypertension with an unexplained unilateral small kidney, and hypertension with intolerance to medication (Class IIa recommendation/Level of Evidence: B).
Preservation of Renal Function:
- 1.
Percutaneous revascularization is reasonable for patients with RAS and progressive chronic kidney disease with bilateral RAS or a RAS to a solitary functioning kidney (Class IIa recommendation/Level of Evidence: B).
- 2.
Percutaneous revascularization may be considered for patients with RAS and chronic renal insufficiency with unilateral RAS (Class IIb recommendation/Level of evidence: C).
Impact of RAS on Congestive Heart Failure and Unstable Angina:
- 1.
Percutaneous revascularization is indicated for patients with hemodynamically significant RAS and recurrent, unexplained congestive heart failure or sudden, unexplained pulmonary edema (Class I recommendation/Level of Evidence: B).
- 2.
Percutaneous revascularization is reasonable for patients with hemodynamically significant RAS and unstable angina (Class IIa recommendation/Level of Evidence: B).
Endovascular Treatment for RAS:
- 1.
Renal stent placement is indicated for ostial atherosclerotic RAS lesions that meet the clinical criteria for intervention (Class I recommendation/Level of Evidence: B).
- 2.
Balloon angioplasty with bailout stent placement, if necessary, is recommended for fibromuscular dysplasia lesions (Class I recommendation/Level of Evidence: B).
Surgery for RAS:
- 1.
Vascular surgical reconstruction is indicated for patients with fibromuscular dysplastic RAS with clinical indications for interventions (same as for percutaneous transluminal angioplasty), especially those exhibiting complex disease that extends into the segmental arteries and those having macroaneurysms (Class I recommendation/Level of Evidence: B).
- 2.
Vascular surgical reconstruction is indicated for patients with atherosclerotic RAS and clinical indications for intervention, especially those with multiple small renal arteries or early primary branching of the main renal artery (Class I recommendation/Level of Evidence: B).
- 3.
Vascular surgical reconstruction is indicated for patients with atherosclerotic RAS in combination with pararenal aortic reconstructions (in treatment of aortic aneurysms or severe aortoiliac occlusive disease) (Class I recommendation/Level of Evidence: C).
5.1.2 European Society of Cardiology (ESC)
Recommendations for diagnostic strategies for RAS (Tendera et al. 2011):
Duplex ultrasonography is recommended as the first-line imaging test to establish the diagnosis of RAS (Class I recommendation/Level of Evidence: B).
In patients with a creatinine clearance >60 mL/min, CTA (computed tomography angiography) is recommended to establish the diagnosis of RAS (Class I recommendation/Level of Evidence: B).
In patients with a creatinine clearance > 30 mL/min, MRA (magnetic resonance angiography) is recommended to establish the diagnosis of RAS (Class I recommendation/Level of Evidence: B).
When the clinical index of suspicion is high and the results of non-invasive tests are inconclusive, DSA (digital subtraction angiography) is recommended as a diagnostic test (prepared for intervention) to establish the diagnosis of RAS (Class I recommendation/Level of Evidence: C).
Captopril renal scintigraphy, selective renal vein renin measurements, plasma renin activity, and the captopril test are not recommended as useful screening tests to establish the diagnosis or RAS (Class III recommendation/Level of Evidence: B).
The therapeutic recommendations of the ESC include medical, endovascular, and surgical therapy. They differ only slightly from those of the AHA, and are framed more cautiously in regard to surgical and endovascular treatment. Whereas the AHA rates a therapy as indicated, the ESC deems it “worth considering”.
Medical therapy:
ACE inhibitors, angiotensin II receptor antagonists, and calcium channel blockers are effective medications for treatment of hypertension associated with unilateral RAS (Class I recommendation/Level of Evidence: B).
ACE inhibitors and angiotensin II receptor blockers are contraindicated in bilateral severe RAS and in the case of RAS in single functional kidney (Class III recommendation/Level of Evidence: B).
Endovascular therapy:
Angioplasty, preferably with stenting, may be considered in the case of >60% symptomatic RAS secondary to atherosclerosis (Class IIb recommendation/Level of Evidence: A).
In the case of indication for angioplasty, stenting is recommended in ostial atherosclerotic RAS (Class I recommendation/Level of Evidence: B).
Endovascular treatment of RAS may be considered in patients with impaired renal function (Class IIb recommendation/Level of Evidence: B).
Treatment of RAS, by balloon angioplasty with or without stenting, may be considered for patients with RAS and unexplained recurrent congestive heart failure or sudden pulmonary oedema and preserved systolic left ventricular function (Class IIb recommendation/Level of Evidence: C).
Surgical therapy:
Surgical revascularization may be considered for patients undergoing surgical repair of the aorta, patients with complex anatomy of the renal arteries, or after a failed endovascular procedure (Class IIb recommendation/Level of Evidence: C).
5.1.3 Revascularization for Renal Artery Fibromuscular Dysplasia (FMD)
5.1.3.1 Scientific Statement from the American Heart Association
The AHA has published a statement regarding renal artery revascularization in patients with renal artery FMD (Olin et al. 2014). The authors found that randomized, controlled trials of revascularization versus medical therapy in patients with renal artery FMD have not been performed. The negative trials on stent implantation for atherosclerotic renal artery disease do not apply to patients with FMD given the differing pathophysiology and natural history of these two vascular disorders.
Indications for renal artery revascularization in patients with FMD are as follows:
Resistant hypertension
Hypertension of short duration with the goal of a cure of hypertension
Renal artery dissection; rarely is intervention needed, but if so, stenting is generally the procedure of choice
Renal artery aneurysm(s); surgical resection, endovascular coiling, or placement of a covered stent is usually used
Branch renal artery disease and hypertension; some lesions can be treated with PTA, but if this is not possible, surgical revascularization may be required, often with bench repair
Preservation of renal function in the patient with severe stenosis, especially in the pediatric population with perimedial or intimal fibroplasia.
In younger patients with recent onset of hypertension, percutaneous angioplasty may be considered first-line therapy with the goal of cure of hypertension. PTA offers many advantages over traditional surgical repair. It is less invasive and less expensive, has a lower morbidity, can be performed on an outpatient basis in many cases, and has a markedly reduced recovery time. Consequently, PTA of the renal artery is the procedure of choice for patients with renal artery FMD and hypertension in the appropriate clinical setting. However, there are patients in whom the expected outcome from surgery may be better than that expected with PTA. Examples include patients with small renal arteries (<4 mm), branch disease, especially when associated with aneurysms, or extensive intimal or perimedial fibroplasia. Secondary surgical repair after failed PTA should be considered early in the decision process before chronic ischemia leads to loss of cortical thickness.
5.1.3.2 European Consensus on the Diagnosis and Management of Fibromuscular Dysplasia
In hypertensive patients with FMD-related RAS, revascularization is recommended (Persu et al. 2014):
- 1.
In the case of hypertension of recent onset, as a first-line treatment to normalize blood pressure.
- 2.
In cases of medical treatment failure (drug resistance or intolerance).
- 3.
In case of renal insufficiency or deterioration of renal function especially after administration of an angiotensin converting enzyme inhibitor, an angiotensin II receptor blocker or a renin inhibitor.
- 4.
In case of renal size reduction downstream of the stenosis.
The two options available for renal artery revascularization are balloon PTA and renal artery surgery. It is impossible to reliably compare the results of both revascularization techniques because they are not performed in patients with similar characteristics. Furthermore, surgical revascularization has been performed for a longer time than PTA revascularization, and the assessment methods therefore also differ in series using surgery or PTA.
In view of its less invasive character and of the large experience acquired, PTA without stenting is currently the first-line revascularization technique in FMD-related RAS. Indeed, there is no evidence of superiority of renal artery PTA followed by stenting vs. PTA alone in FMD patients. Furthermore, several cases of stent fracture have been reported in patients with renal FMD, possibly owing to an increased kinetic stress related to severe kidney ptosis. Accordingly, stenting is not indicated after primary PTA unless needed because of a significant per-procedural dissection.
Surgery remains the primary approach for patients with complex lesions of arterial bifurcation or branches, stenoses associated with complex aneurysms, or following PTA failure.
Cutting balloons, proposed by some authors as an alternative to surgery in case of PTA failure, are not recommended in patients with FMD because of the risk of renal artery rupture and subsequent pseudoaneurysm formation.
5.1.4 Addendum
The 2015 Canadian Hypertension Education Program recommendations for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension are (Daskalopoulou et al. 2015):
- 1.
Renal artery stenosis (RAS) should be primarily managed medically.
- 2.
Renal artery angioplasty and stenting could be considered for patients with RAS and complicated, uncontrolled hypertension.
Expert consensus statement for renal artery stenting appropriate use by the Society for Cardiovascular Angiography and Interventions (SCAI) (Parikh et al. 2014). Appropriate care of significant RAS:
Cardiac Disturbance Syndromes (Flash Pulmonary Edema or acute coronary syndrome (ACS)) with severe hypertension.
Resistant HTN (Uncontrolled hypertension with failure of maximally tolerated doses of at least three antihypertensive agents, one of which is a diuretic, or intolerance to medications).
Ischemic nephropathy with chronic kidney disease (CKD) with eGFR < 45 cc/min and global renal ischemia (unilateral significant RAS with a solitary kidney or bilateral significant RAS) without other explanation.
5.2 Results
5.2.1 Endovascular Therapy
5.2.1.1 Systematic Reviews/Meta-analyses
Riaz et al. (2014) performed a meta-analysis to compare the efficacy of revascularization versus medical therapy in patients with atherosclerotic renal artery stenosis. Two thousand, one-hundred and thirty-nine patients were included in the final analysis. Angioplasty with or without stenting was not superior to medical therapy with respect to any outcome. The incidence of nonfatal myocardial infarction was 6.74% in both the stenting and medical therapy group, and incidence of renal events in stenting population was found to be 19.58% versus 20.53% in medical therapy population. In conclusion, PTA +/− stent placement did not improve outcomes compared with medical therapy in patients with atherosclerotic RAS. Jenks et al. (2014) addressed the same question. They updated a Cochrane review first published in 2003. Eight randomized controlled trials, involving 2111 participants, 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 6 months were included in this meta-analysis. They stressed that the available data are insufficient to conclude that revascularization in the form of balloon angioplasty, with or without stenting, is superior to medical therapy for the treatment of atherosclerotic RAS 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.
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