Safety and Efficacy of Renal Artery Stenting Following Suboptimal Renal Angioplasty for De Novo and Restenotic Ostial Lesions: Results from a Nonrandomized, Prospective Multicenter Registry

Safety and Efficacy of Renal Denervation in Patients Taking Antihypertensive Medications

BACKGROUND

Renal denervation (RDN) reduces blood pressure (BP) in patients with uncontrolled hypertension in the absence of antihypertensive medications.

OBJECTIVES

This trial assessed the safety and efficacy of RDN in the presence of antihypertensive medications.

METHODS

SPYRAL HTN-ON MED is a prospective, randomized, sham-controlled, patient- and assessor-blinded trial enrolling patients from 56 clinical centers worldwide. Patients were prescribed 1 to 3 antihypertensive medications. Patients were randomized to radiofrequency RDN or sham control procedure. The primary efficacy endpoint was the baseline-adjusted change in mean 24-hour ambulatory systolic BP at 6 months between groups using a Bayesian trial design and analysis.

RESULTS

The treatment difference in the mean 24-hour ambulatory systolic BP from baseline to 6 months between the RDN group (n = 206; -6.5 ± 10.7 mm Hg) and sham control group (n = 131; -4.5 ± 10.3 mm Hg) was -1.9 mm Hg (95% CI: -4.4 to 0.5 mm Hg; P = 0.12). There was no significant difference between groups in the primary efficacy analysis with a posterior probability of superiority of 0.51 (Bayesian treatment difference: -0.03 mm Hg [95% CI: -2.82 to 2.77 mm Hg]). However, there were changes and increases in medication intensity among sham control patients. RDN was associated with a reduction in office systolic BP compared with sham control at 6 months (adjusted treatment difference: -4.9 mm Hg; P = 0.0015). Night-time BP reductions and win ratio analysis also favored RDN. There was 1 adverse safety event among 253 assessed patients.

CONCLUSIONS

There was no significant difference between groups in the primary analysis. However, multiple secondary endpoint analyses favored RDN over sham control. (SPYRAL HTN-ON MED Study [Global Clinical Study of Renal Denervation With the Symplicity Spyral Multi-electrode Renal Denervation System in Patients With Uncontrolled Hypertension in the Absence of Antihypertensive Medications]; NCT02439775).

Renal Artery Revascularization a controversial treatment strategy for Renal Artery Stenosis. A case series and a brief review of current literature

Renal artery stenosis (RAS) may cause secondary hypertension, progressive decline in renal function, and cardiac destabilization syndromes including "flash" pulmonary edema, recurrent congestive heart failure, and cerebro-cardiovascular disease. Atherosclerotic lesions, fibromuscular dysplasia and vasculitides are the pathophysiologic basis of the disease. Common therapeutic pathways for RAS include medical therapy and revascularization with or without stenting. Randomized controlled trials evaluating renal revascularization, did not report any advantage of revascularization over medical therapy alone in terms of renal function improvement or prevention of cardiovascular events. However, mounting clinical experience suggests that the best strategy in RAS management is identifying which patients are most likely to benefit from renal artery stenting and also optimizing the safety and durability of the procedure. This review presents 3 cases of patients who undergone renal revascularization and discusses the available clinical evidence for identification of RAS patients who will potentially respond well to revascularization.

Results of renal artery revascularization in the post-ASTRAL era with 4 years mean follow-up

Purpose: To investigate contemporary results of percutaneous transluminal renal angioplasty (PTRA).Materials and Methods: A multicentre retrospective study analysing all patients treated with PTRA for primary symptomatic renal artery stenosis (RAS) between 2010 and 2013 at four tertiary centres. Procedures during the preceding four years were counted to evaluate for change in PTRA frequency.Results: The number of PTRA procedures decreased by approximately 50% from 2006 to 2013. Patients treated in the post-ASTRAL period (n = 224) had a significant reduction in mean systolic pressure (168 to 146 mmHg, p < 0.01), diastolic pressure (84 to 76 mmHg, p < 0.01), number of anti-hypertensive drugs (3.54 to 3.05, p < 0.01), and anti-hypertensive treatment index (21.75 to 16.92, p < 0.01) compared to before PTRA. These improvements were maintained at one year and at the last clinical evaluation after a mean follow-up of 4.31 years. Renal function increased transiently without sustained improvement, or deterioration, during later follow-up. Thirteen patients (5.8%) eventually required dialysis, nine of these had eGFR <20 ml/min/1.73 m² before PTRA. There was no difference in outcomes between subgroups differentiated by different indications for PTRA.Conclusion: The frequency of PTRA has decreased, indicating a higher threshold for invasive treatment of RAS in recent years. The reduction in blood pressures, the reduced need for anti-hypertensive medication, and stabilization of renal function over time suggest a clinical benefit for most patients who are now being treated with PTRA.

Rationale and design of two randomized sham-controlled trials of catheter-based renal denervation in subjects with uncontrolled hypertension in the absence (SPYRAL HTN-OFF MED Pivotal) and presence (SPYRAL HTN-ON MED Expansion) of antihypertensive medications: a novel approach using Bayesian design

BACKGROUND

The SPYRAL HTN clinical trial program was initiated with two 80-patient pilot studies, SPYRAL HTN-OFF MED and SPYRAL HTN-ON MED, which provided biological proof of principle that renal denervation has a blood pressure-lowering effect versus sham controls for subjects with uncontrolled hypertension in the absence or presence of antihypertensive medications, respectively.

TRIAL DESIGN

Two multicenter, prospective, randomized, sham-controlled trials have been designed to evaluate the safety and efficacy of catheter-based renal denervation for the reduction of blood pressure in subjects with hypertension in the absence (SPYRAL HTN-OFF MED Pivotal) or presence (SPYRAL HTN-ON MED Expansion) of antihypertensive medications. The primary efficacy endpoint is baseline-adjusted change from baseline in 24-h ambulatory systolic blood pressure. The primary safety endpoint is incidence of major adverse events at 1 month after randomization (or 6 months in cases of new renal artery stenosis). Both trials utilize a Bayesian design to allow for prespecified interim analyses to take place, and thus, the final sample sizes are dependent on whether enrollment is stopped at the first or second interim analysis. SPYRAL HTN-OFF MED Pivotal will enroll up to 300 subjects and SPYRAL HTN-ON MED Expansion will enroll up to 221 subjects. A novel Bayesian power prior approach will leverage historical information from the pilot studies, with a degree of discounting determined by the level of agreement with data from the prospectively powered studies.

CONCLUSIONS

The Bayesian paradigm represents a novel and promising approach in device-based hypertension trials.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02439749 (SPYRAL HTN-OFF MED Pivotal) and NCT02439775 (SPYRAL HTN-ON MED Expansion).

Long-term outcome of stenting for atherosclerotic renal artery stenosis and the effect of angiographic restenosis

BACKGROUND

Symptomatic renal artery stenosis (RAS) is mainly treated with pharmacological blood pressure control, sometimes with percutaneous transluminal renal angioplasty (PTRA). It is unclear if PTRA benefits these patients over time.

PURPOSE

To determine long-term renal function, morbidity, and mortality in patients with symptomatic RAS treated with PTRA, and whether long-term outcomes are associated with angiographic restenosis.

MATERIAL AND METHODS

Retrospective single-center, long-term follow-up of 57 patients with atherosclerotic RAS treated with PTRA with stent during 1995-2004 and investigated for restenosis with angiography after one year. Outcomes were retrieved from medical records and from mandatory healthcare registries. Mortality rates were related to expected survival in an age- and gender-matched population, using a life-table database. Surviving patients were assessed with blood pressures, laboratory tests, duplex ultrasonography, and radioisotope renography.

RESULTS

Median follow-up was 11 years 7 months. Major indications for PTRA were therapy-resistant hypertension and declining renal function. Angiographic restenosis at one year was found in 21 of 57 patients (37%). Thirty-six patients (60%) died during follow-up. Main cause of death was cardiovascular events (54%). Mortality was significantly increased, and morbidity and healthcare utilization were high. Hypertension control during follow-up was stable with persistent need for anti-hypertensive medication, and renal function remained moderately reduced with no long-term difference between patients with vs. without restenosis.

CONCLUSION

Long-term prognosis after PTRA for atherosclerotic RAS is dismal, with high mortality and morbidity and reduced renal function, despite maintained hypertension control. Restenosis does not appear to affect late outcome.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Issues related to renal artery angioplasty and stenting

Renal artery stenosis may play a significant role in the pathogenesis of secondary hypertension, renal dysfunction, and flash pulmonary edema. Currently correction of renal arterial inflow stenosis is reserved for resistant hypertension patients who have failed maximal medical therapy, have worsening renal function and/or unexplained proximal congestive failure. With the recent advances in minimally invasive percutaneous stent placement techniques, open surgical revascularization has been largely replaced by renal artery stenting. The potential benefit of revascularization seemed intuitive; however, the initial enthusiasm and rise in the number of percutaneous interventions have been tempered by many subsequent negative randomized clinical trials that failed to prove the proposed benefits of the percutaneous intervention. The negative randomized trial results have fallen under scrutiny due to trial design concerns and inconsistent outcomes of these studies compared to pivotal trials undertaken under US Food and Drug Administration scrutiny. Treatment of atherosclerotic renal artery occlusive disease has become one of the most debatable topics in the field of vascular disease. The results from recent randomized clinical trials of renal artery stenting have basically limited the utilization of the procedure in many centers, but not every clinical scenario was covered in those trials. There are potential areas for improvement focusing mainly on procedural details and patient selection with respect to catheter based treatment of atherosclerotic renal artery stenosis. We believe, limiting patient selection, enrollment criteria and outcomes measured functioned to reduce the benefit of renal artery stenosis stenting by not enrolling patients likely to benefit. Future studies incorporating potential procedural improvements and that include patients more likely to benefit from renal stenting than were included in ASTRAL and CORAL are needed to more carefully examine specific patient subgroups so that “the baby is not thrown out with the bath water.” We also discuss several other concerns related to renal artery stenting which include diagnostic, procedure, indication, and reimbursement issues.

Issues related to renal artery angioplasty and stenting

Renal artery stenosis may play a significant role in the pathogenesis of secondary hypertension, renal dysfunction, and flash pulmonary edema. Currently correction of renal arterial inflow stenosis is reserved for resistant hypertension patients who have failed maximal medical therapy, have worsening renal function and/or unexplained proximal congestive failure. With the recent advances in minimally invasive percutaneous stent placement techniques, open surgical revascularization has been largely replaced by renal artery stenting. The potential benefit of revascularization seemed intuitive; however, the initial enthusiasm and rise in the number of percutaneous interventions have been tempered by many subsequent negative randomized clinical trials that failed to prove the proposed benefits of the percutaneous intervention. The negative randomized trial results have fallen under scrutiny due to trial design concerns and inconsistent outcomes of these studies compared to pivotal trials undertaken under US Food and Drug Administration scrutiny. Treatment of atherosclerotic renal artery occlusive disease has become one of the most debatable topics in the field of vascular disease. The results from recent randomized clinical trials of renal artery stenting have basically limited the utilization of the procedure in many centers, but not every clinical scenario was covered in those trials. There are potential areas for improvement focusing mainly on procedural details and patient selection with respect to catheter based treatment of atherosclerotic renal artery stenosis. We believe, limiting patient selection, enrollment criteria and outcomes measured functioned to reduce the benefit of renal artery stenosis stenting by not enrolling patients likely to benefit. Future studies incorporating potential procedural improvements and that include patients more likely to benefit from renal stenting than were included in ASTRAL and CORAL are needed to more carefully examine specific patient subgroups so that "the baby is not thrown out with the bath water." We also discuss several other concerns related to renal artery stenting which include diagnostic, procedure, indication, and reimbursement issues.

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.

Where and when device therapy may be useful in the management of drug-resistant hypertension

Device therapy for the treatment of uncontrolled and resistant hypertension has evolved significantly over the past several decades. Both renal artery disease and sympathetic hyperactivity have been linked to resistant hypertension. This manuscript will review the current evidence base supporting device therapy (e.g., renal artery revascularization, sympathetic nervous system modulation) for resistant hypertension.

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.

Blood pressure response to renal artery stenting in 901 patients from five prospective multicenter FDA-approved trials

BACKGROUND

Renal artery stent revascularization is commonly used for renovascular hypertension. Clinical predictors associated with blood pressure (BP) improvement after renal artery stent revascularization are not well understood.

METHODS

Patient-level data from 901 patients in five prospective multicenter Food and Drug Administration-approved investigational device exemption studies of renal artery stent revascularization was pooled. BP response was defined as reduction of systolic BP (SBP) by >10 mm Hg. Stent patency was defined within each study. Associations of BP reduction were determined by logistic regression.

RESULTS

Of 901 patients, complete outcome information was available in 527. Of these, 212/527 (40%) were male, mean age was 63 ± 13 years, 196/544 (36%) were diabetic and 504/527 (96%) had a SBP ≥ 140 mm Hg or DBP ≥ 90 mm Hg at baseline. Compared to baseline, 9-month systolic (164 ± 21 mm Hg vs. 146 ± 22 mm Hg, P < 0.0001) and diastolic (79 ± 13 mm Hg vs. 76 ± 12 mm Hg, P < 0.0001) BP declined significantly. Nine-month stent patency was 90% (305/339). In a univariate analysis, baseline SBP >150 mm Hg (OR = 4.09, CI = 2.74-6.12, P < 0.0001) was positively associated with BP response following renal artery stent revascularization. In a multivariable analysis, baseline SBP remained associated with a positive BP response (OR = 1.76, CI = 1.53-2.03, P < 0.0001).

CONCLUSIONS

In the largest pooled dataset of patients treated with renal artery stent revascularization, SBP and DBP were significantly lower at 9-months. Elevated baseline SBP (>150 mm Hg) was strongly associated with BP reduction after the procedure.

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.

Objective performance goals of safety and blood pressure efficacy for clinical trials of renal artery bare metal stents in hypertensive patients with atherosclerotic renal artery stenosis

OBJECTIVE

To provide safety and performance goals for prospective single-arm trials of bare metal renal artery stenting in patients with resistant hypertension associated with high grade atherosclerotic renal artery stenosis.

BACKGROUND

To date, there have been no US Pre-Market Approval (PMA) bare metal renal stent device trials which have focused on improvement of blood pressure control as a primary effectiveness endpoint.

METHODS

Analysis of subject-level data from three large industry sponsored pre-market approval (PMA) trials was performed. Hypertensive patients (≥ 155 mmHg) with a ≥ 50% atherosclerotic renal artery stenosis were included. Thirty day and 9-month systolic and diastolic blood pressure measurements, renal function and 9-month duplex ultrasound assessment of renal artery patency were analyzed.

RESULTS

Initial data analysis of 600 patients from the 3 PMA trials identified 286 patients who met inclusion criteria. The mean baseline systolic blood pressure was 177.8 ± 19.3 mmHg with a mean 68.1% diameter renal artery stenosis. Nine months after successful stenting, the mean SBP was 156.7 ± 24.1 mmHg; the 9 month restenosis rate was 14.4%.

CONCLUSION

Based on the statistical modeling of these data and a priori established performance criteria, the co-primary endpoints of 9 month reduction in blood pressure and in-stent restenosis are proposed. The reduction in blood pressure will be analyzed as a continuous variable and will be compared to this performance goal.