Renal sympathetic denervation therapy for resistant hypertension: a contemporary synopsis and future implications

Systematic Review and Meta-Analysis of Second-Generation Sham-Controlled Randomized Trials of Renal Denervation Therapy for Patients with Hypertension

INTRODUCTION

Renal denervation has been associated with substantial and sustained blood pressure reduction and is considered to serve as an alternative treatment for patients with resistant hypertension. However, the first published SHAM-controlled trial assessing RDN safety and efficacy showed no difference between groups.

AIM

We aimed to perform a meta-analysis quantifying the magnitude of blood pressure decrease secondary to renal denervation in patients with resistant hypertension.

METHODS

Databases were searched for RCTs that compared RDN therapy to SHAM procedure and reported the outcomes of (1) 24-hour ambulatory blood pressure; (2) Office systolic blood pressure; (3) Daytime systolic blood pressure; and (4) Night-time systolic blood pressure. Mean differences with 95% confidence intervals (CIs) were calculated using a random-effects model. Heterogeneity was examined with I² statistics. P values of < 0.05 were considered statistically significant. Statistical analyses were performed using RStudio 4.2.3.

RESULTS

Nine studies and 1622 patients were included. The AMBP [MD -3.72 95%CI -5.44, -2.00 p < 0.001; I²=34%] and DSBP [MD -4.10 95%CI -5.84, -2.37 p < 0.001; I²=0%] were significantly reduced in the RDN arm. ODBP [MD -6.04 95%CI -11.31, -0.78 p = 0.024; I²=90%] and NSBP [MD -1.81 95%CI -3.90, 0.27 p = 0.08; I²=0%] did not reach a statistically significant difference between groups.

CONCLUSION

Renal denervation demonstrates greater efficacy in reducing 24-hour ambulatory and daytime systolic blood pressure in patients diagnosed with resistant hypertension.

Comparing the Efficacy of Renal Artery Denervation in Uncontrolled Hypertension: A Systematic Review and Network Meta-Analysis

The study aims to compare the outcomes of different renal denervation (RDN) procedures in the treatment of uncontrolled hypertension. We searched Scopus, PubMed, Web of Science, and Cochrane for RCTs evaluating different procedures of RDN for hypertension. The outcomes of this study were systolic blood pressure (SBP) daytime, diastolic blood pressure (DBP) daytime, SBP nighttime, DBP nighttime, SBP 24-hour, DBP 24-hour, SBP home, DBP home, SBP office, and DBP office. We did a frequentist network meta-analysis of 38 published RCTs evaluating the efficacy of different renal artery denervation procedures for uncontrolled hypertension compared to sham procedures or standardized stepped-care antihypertensive treatment (SSAHT). Radiofrequency (RF) alone showed a statistically significant reduction in DBP (24 hours), DBP (daytime), and DBP (nighttime): standardized mean difference (SMD): -2.01 (95% CI: (-3.34; -0.68)), SMD: -4.36 (95% CI: (-8.28; -0.44)), and SMD: -3.50 (95% CI: (-6.23; -0.76)), respectively, and showed a statistically significant reduction in SBP (24 hours), SBP (daytime), and SBP (nighttime): SMD: -3.93 (95% CI: (-6.01; -1.84)), SMD: -5.88 (95% CI: (-9.91; -1.85)), and SMD: -5.79 (95% CI: (-10.0; -1.58)), respectively. RF added to SSAHT has statistical significance in the reduction of DBP (nighttime), SBP (daytime), SBP (home), and SBP (nighttime) with a SMD of -7.63 (95% CI: (-14.21; -1.06)), SMD of -10.56 (95% CI: (-21.03; -0.08)), SMD of -23.20 (95% CI: (-36.72; -9.26)), and SMD of -14.03 (95% CI: (-25.43; -2.63)), respectively. We found that renal denervation, especially by RF, when added to SSAHT may be a promising therapeutic option for patients with treatment-resistant hypertension, particularly in cases where medication alone fails to achieve adequate blood pressure control.

Update on Renal Sympathetic Denervation for the Treatment of Hypertension

PURPOSE OF REVIEW

Hypertension is a leading risk factor for all-cause mortality in adults; however, medication non-adherence and intolerance present an enormous treatment challenge. Given the critical role of renal sympathetic nerves in neurogenic control of blood pressure and pathophysiology of hypertension, renal sympathetic denervation (RDN) has been explored as a therapeutic strategy in hypertension treatment over the last 15 years. In this review, we will discuss the role of renal sympathetic nerves in the pathophysiology of hypertension, provide an update on the available evidence regarding the short- and long-term safety and effectiveness of RDN in the treatment of hypertension, and consider its future perspectives.

RECENT FINDINGS

RDN is a percutaneous endovascular catheter-based neuromodulation approach that enables ablation of renal sympathetic nerve fibers within the adventitial layer of the renal arteries using radiofrequency (most extensively studied), ultrasound energy, or neurolytics (e.g., alcohol). In the last decade, advancements in procedural techniques and well-designed sham-controlled trials utilizing 24-h ambulatory blood pressure measurements have demonstrated that RDN has an excellent safety profile and results in a modest reduction of blood pressure, in a wide range of hypertensive phenotypes (mild to resistant), irrespective of antihypertensive drug use and this effect is sustained over a 3-year period. Superiority of a particular RDN modality has not been yet established. Despite strong evidence demonstrating efficacy and safety of RDN, current data does not support its use as a primary approach in the treatment of hypertension due to its modest treatment effect and concerns around long-term sustainability. Perhaps the best utility of RDN is in hypertensives intolerant to antihypertensive medications or as an adjunct to aldosterone antagonists in the management of resistant hypertension. Patient selection will be critical to demonstrate a meaningful benefit of RDN. Future well-designed studies are necessary to determine predictors and measures of response to RDN, long-term efficacy given question of renal nerve regeneration, comparison of available technologies, safety in patients with advanced kidney disease, and improvement in patient quality of life measures.

Renal denervation in a patient with a highly tortuous renal artery using a guide extension catheter: a case report

Background

Catheter-based renal denervation (RDN) has been introduced to treat resistant hypertension. Although the technology of RDN has been largely improved, denervation of tortuous renal arteries remains challenging.

Case presentation

This is a case report of a 49-year-old man with drug resistant hypertension. The patient was selected for RDN after ruling out possible causes of secondary hypertension. Computed tomography angiography showed a highly tortuous left renal artery. An Iberis multielectrode ablation catheter failed to reach the target vessel with a regular guiding catheter. A 5-French extension catheter was introduced into the proximal segment of the main left renal artery to provide extra support force, which enabled successful ablation of the highly tortuous left renal artery. His ambulatory blood pressure was significantly decreased at 1 month follow-up.

Conclusions

It is feasible and effective to use a guide extension catheter for denervation of highly tortuous renal arteries. The present study provides a useful method to ablate tortuous and angled renal arteries and branches.

[Selection of Patients with Resistant Arterial Hypertension for the Catheter-Based Renal Sympathetic Denervation]

PURPOSE

elaboration of algorithm for selection of patients with resistant arterial hypertension (AH) for Catheter-Based Renal Sympathetic Denervation (CBRSD).

MATERIALS AND METHODS

We examined 284 patients with resistant AH. On stage 1 we excluded most frequent causes of secondary AH. In 247 patients (86.9 %) we established secondary character of AH, in 37 patients (13.1 %) AH was found to be essential. On stage 2 patients with essential AH were given 3-5 component hypotensive therapy. At the background of this therapy we conducted 24‑hour ambulatory blood pressure monitoring (ABPM). CBRSD procedure was considered indicated if according to ABPM average 24‑hour blood pressure (BP) was above 150 and 100 mm Hg, and 24‑hour elevated BP load exceeded 60 %. In 13 of 37 patients (35 %) BP level satisfied these conditions. For CBRSD we used high frequency generator. Ablation was performed using the Symplicity Catheter. Results were assessed in 1, 2, 9, 12, and 28 months.

RESULTS

Target BP level at the background of minimal doses of hypotensive drugs was achieved in 11 patients (85 %), what was confirmed by ABPM data. Levels of mean 24-4 hour systolic and diastolic BP significantly decreased from 173.9±14.9 to 143±21.3, р&lt;0.05, and from 108.2±8.7 to 91.4±13.8 mm Hg., р&lt;0.05, respectively. Index of elevated systolic BP time decreased from 78.2±14.6 to 49.8±29.6 %, р&lt;0.05. Best effect was achieved in patients with AH duration before the procedure less than 7 years. None of the patients had episodes of cerebral vascular insufficiency or heart failure progression.

CONCLUSION

While determining indications to bilateral CBRSD one should be governed by such criteria as exclusion of symptomatic AH and objective proofs of AH resistance (according to ABPM at the background of hypotensive therapy).

Renal Denervation to Modify Hypertension and the Heart Failure State

Sympathetic overactivation of renal afferent and efferent nerves have been implicated in the development and maintenance of several cardiovascular disease states, including resistant hypertension and heart failure with both reduced and preserved systolic function. With the development of minimally invasive catheter-based techniques, percutaneous renal denervation has become a safe and effective method of attenuating sympathetic overactivation. Percutaneous renal denervation, therefore, has the potential to modify and treat hypertension and congestive heart failure. Although future randomized controlled studies are needed to definitively prove its efficacy, renal denervation has the potential to change the way we view and treat cardiovascular disease.

Renal Denervation vs Pharmacotherapy for Resistant Hypertension: A Meta-Analysis

The effect of renal denervation (RD) for resistant hypertension remains controversial because of the conflicting results of finished and ongoing studies. The authors performed a meta-analysis of case-control studies to identify whether renal sympathetic denervation or pharmacotherapy (PHAR) was more effective for resistant hypertension. A systematic Internet database search of relevant papers written in English was performed. A total of nine studies met the inclusion criteria, with a total of 1096 patients. When comparing the RD group with the PHAR group, there was a significant decrease in systolic blood pressure (SBP) (weighted mean difference, -12.81 mm Hg; 95% confidence interval [CI], -22.77 mm Hg to -2.85 mm Hg; P=.01) and diastolic blood pressure (DBP) (weighted mean difference, -5.56; 95% CI, -8.15 mm Hg to -2.97 mm Hg; P<.0001). This pooled analysis shows that for patients with resistant hypertension, RD is more effective in reducing SBP and DBP than PHAR. RD may be more effective in special subgroups of patients, which needs to be identified in future investigations.

The rise, fall, and possible resurrection of renal denervation

Renal denervation has a chequered history. Dramatic reductions in blood pressure after denervation of the renal arteries were observed in early trials, but later trials in which denervation was tested against a sham procedure produced neutral results. Although a sound pathophysiological basis exists for interruption of the renal sympathetic nervous system as a treatment for hypertension, trial data to date are insufficient to support renal denervation as an established clinical therapy. In this Perspectives article, we summarize the currently available trial data, device development, and trials in progress, and provide recommendations for future trial design.

Renal sympathetic denervation using MR-guided high-intensity focused ultrasound in a porcine model

Background

Initial catheter-based renal sympathetic denervation (RSD) studies demonstrated promising results in showing a significant reduction of blood pressure, while recent data were less successful. As an alternative approach, the objective of this study was to evaluate the feasibility of using magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) to perform RSD in a porcine model.

Methods

An intravascular fiber optic temperature probe was used to confirm energy delivery during MRgHIFU. This technique was evaluated both in a vascular phantom and in a normotensive pig model. Five animals underwent unilateral RSD using MRgHIFU, and both safety and efficacy were assessed. MRI was used to evaluate the acoustic window, target sonications, monitor the near-field treatment region using MR thermometry imaging, and assess the status of tissues post-procedure. An intravascular fiber optic temperature probe verified energy delivery. Animals were sacrificed 6 to 9 days post-treatment, and pathological analysis was performed. The norepinephrine present in the kidney medulla was assessed post-mortem.

Results

All animals tolerated the procedure well with no observed complications. The fiber optic temperature probe placed in the target renal artery confirmed energy delivery during MRgHIFU, measuring larger temperature rises when the MRgHIFU beam location was focused closer to the tip of the probe. Following ablation, a significant reduction (p = 0.04) of cross-sectional area of nerve bundles between the treated and untreated renal arteries was observed in all of the animals with treated nerves presenting increased cellular infiltrate and fibrosis. A reduction of norepinephrine (p = 0.14) in the kidney medulla tissue was also observed. There was no indication of tissue damage in arterial walls.

Conclusions

Performing renal denervation non-invasively with MRgHIFU was shown to be both safe and effective as determined by norepinephrine levels in a porcine model. This approach may be a promising alternative to catheter-based strategies.

Renal Denervation in Patients With Uncontrolled Hypertension and Confirmed Adherence to Antihypertensive Medications

Renal denervation (RDN) has emerged as a potential device-based treatment for resistant hypertension. The authors present their experience of the use of catheter-based RDN as part of routine clinical care in two specialist hypertension clinics. Thirty-four patients with uncontrolled hypertension underwent RDN. All patients had ambulatory blood pressure (BP) monitoring and directly observed medication administration prior to the procedure to exclude white-coat hypertension and nonadherence, respectively. Overall, there was a significant change in clinic systolic BP of -15.1 mm Hg (95% confidence interval, -23.4 to -6.8; P=.001) and clinic diastolic BP of -6.2 mm Hg (95% confidence interval, -11.5 to -0.9; P=.02) 6 months postprocedure, and a nonsignificant change in daytime ambulatory BP of -5.4/-2.9 mm Hg. Eighteen patients (51.4%) showed a significant reduction in their clinic systolic BP (≥10 mm Hg) and 16 (47%) had a significant reduction in their daytime ambulatory systolic BP (≥5 mm Hg) at 6 months.

The future of renal denervation in resistant hypertension

Resistant hypertension, defined as inadequate blood pressure control despite three or more antihypertensive medications at maximally tolerated doses, is strongly linked to increased cardiovascular morbidity and mortality. Increased renal afferent and efferent sympathetic activity carried by nerves which arborize the adventitia of the renal arteries, appears to be central to the pathobiology of resistant hypertension. Historical experience indicates that surgical denervation and/or sympathectomy often dramatically reduced blood pressure in patients with malignant hypertension. Catheter-based radio-frequency renal denervation was developed in the past decade as a percutaneous adaptation of surgical denervation. Percutaneous renal denervation using a variety of systems has demonstrated to date, in non-randomized and unblinded studies, dramatic reductions in office-based blood pressure, but more modest impact on ambulatory blood pressure. The only single, appropriately powered, blinded, sham-controlled study of renal denervation conducted to date, however, failed to meet its primary endpoint, casting doubt on the value of the therapy. Ancillary benefits of renal denervation have been described in such conditions as diabetes mellitus, heart failure, and sleep apnea but require further study. While renal denervation is already widely available outside of the USA for commercial use, its utility in resistant hypertension must be vetted by further rigorous investigation before its use can be routinely recommended.

Prevention And Treatment of Hypertension With Algorithm-based therapy (PATHWAY) number 2: protocol for a randomised crossover trial to determine optimal treatment for drug-resistant hypertension

INTRODUCTION

Resistant hypertension is inadequately controlled blood pressure (BP) despite treatment with at least three BP-lowering drugs. A popular hypothesis is that resistant hypertension is due to excessive Na(+)-retention, and that 'further diuretic therapy' will be superior to alternative add-on drugs.

METHODS AND ANALYSIS

Placebo-controlled, random crossover study of fourth-line treatment when added to standard (A+C+D) triple drug therapy: ACE inhibitor or Angiotensin receptor blocker (A) +Calcium channel blocker (C)+Diuretic (D). Patients (aged 18-79 years) with clinical systolic BP ≥ 140 mm Hg (135 mm Hg in diabetics) and Home BP Monitoring (HBPM) systolic BP average ≥ 130 mm Hg on treatment for at least 3 months with maximum tolerated doses of A+C+D are randomised to four consecutive randomly allocated 12-week treatment cycles with an α-blocker, β-blocker, spironolactone and placebo. The hierarchical coprimary end point is the difference in HBPM average systolic BP between (in order) spironolactone and placebo, spironolactone and the average of the other two active drugs, spironolactone and each of the other two drugs. A key secondary outcome is to determine whether plasma renin predicts the BP response to the different drugs. A sample size of 346 (allowing 15% dropouts) will confer 90% power to detect a 3 mm Hg HBPM average systolic BP difference between any two drugs. The study can also detect a 6 mm Hg difference in HBPM average systolic BP between each patient's best and second-best drug predicted by tertile of plasma renin.

ETHICS AND DISSEMINATION

The study was initiated in May 2009 and results are expected in 2015. These will provide RCT evidence to support future guideline recommendations for optimal drug treatment of resistant hypertension.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT02369081, EUDract number: 2008-007149-30.

[New invasive therapies for management of resistant hypertension]

The failure of pharmacological approaches to treat resistant hypertension has stimulated interest in invasive device-based treatments. New catheter systems using radiofrequency or ultrasound energy have been developed, allowing a percutaneous endovascular approach to renal denervation for patients with resistant hypertension. To date, this technique has been evaluated only in a few open-label trials including small numbers and the available evidence suggests a favorable blood pressure-lowering effect in the short-term and a low incidence of immediate complications. All studies published to date have several limitations due to their open-label design. Carotid baroreceptor stimulation requires surgical implantation of electrodes connected to a stimulator. Preliminary results show a positive effect on blood pressure with a complication rate similar to the implantation of a pacemaker. In this context, there are arguments against an uncontrolled use of these procedures in routine practice: an unknown benefit/risk ratio, a variable blood pressure response, absence of cost-effectiveness evaluation. The indications of these procedures should follow the 2013 European Society of Hypertension guidelines. A strict follow-up of patients remains necessary at best by including them in clinical trials or international registries.

Proceedings from Duke resistant hypertension think tank

To identify patients at increased risk for cardiovascular outcomes, apparent treatment resistant hypertension (aTRH) is defined as having a blood pressure (BP) above goal despite the use of ≥3 antihypertensive therapies of different classes at maximally tolerated doses, ideally including a diuretic. In light of growing scientific interest in the treatment of this group, a multistakeholder think tank was convened to discuss the current state of knowledge, improve the care of these patients, and identify appropriate study populations for future observational and randomized trials in the field. Although recent epidemiologic studies in selected populations estimate that the prevalence of aTRH is 10% to 15% of hypertensive patients, further large-scale observational studies will be needed to better elucidate risk factors. To spur the development of therapies for aTRH, the development of an "aTRH" label for pharmacologic and device therapies with a developmental pathway including treatment added to the use of existing therapies is favored. Although demonstration of adequate BP lowering should be sufficient to gain Food and Drug Administration approval for therapies targeting aTRH, assessment of improvement in quality of life and cardiovascular outcomes is also desirable and considered in Centers for Medicare and Medicaid Services coverage decisions. Device trials under the aTRH label will need uniform and consistent processes for defining appropriate patient populations as well as postapproval registries assessing both long-term safety and duration of responses. Finally, patients with aTRH are likely to benefit from evaluation by a hypertension team to assure proper patient identification, diagnostic work-up, and therapeutic management before consideration of advanced or novel therapies to lower BP.

A controlled trial of renal denervation for resistant hypertension

BACKGROUND

Prior unblinded studies have suggested that catheter-based renal-artery denervation reduces blood pressure in patients with resistant hypertension.

METHODS

We designed a prospective, single-blind, randomized, sham-controlled trial. Patients with severe resistant hypertension were randomly assigned in a 2:1 ratio to undergo renal denervation or a sham procedure. Before randomization, patients were receiving a stable antihypertensive regimen involving maximally tolerated doses of at least three drugs, including a diuretic. The primary efficacy end point was the change in office systolic blood pressure at 6 months; a secondary efficacy end point was the change in mean 24-hour ambulatory systolic blood pressure. The primary safety end point was a composite of death, end-stage renal disease, embolic events resulting in end-organ damage, renovascular complications, or hypertensive crisis at 1 month or new renal-artery stenosis of more than 70% at 6 months.

RESULTS

A total of 535 patients underwent randomization. The mean (±SD) change in systolic blood pressure at 6 months was -14.13±23.93 mm Hg in the denervation group as compared with -11.74±25.94 mm Hg in the sham-procedure group (P<0.001 for both comparisons of the change from baseline), for a difference of -2.39 mm Hg (95% confidence interval [CI], -6.89 to 2.12; P=0.26 for superiority with a margin of 5 mm Hg). The change in 24-hour ambulatory systolic blood pressure was -6.75±15.11 mm Hg in the denervation group and -4.79±17.25 mm Hg in the sham-procedure group, for a difference of -1.96 mm Hg (95% CI, -4.97 to 1.06; P=0.98 for superiority with a margin of 2 mm Hg). There were no significant differences in safety between the two groups.

CONCLUSIONS

This blinded trial did not show a significant reduction of systolic blood pressure in patients with resistant hypertension 6 months after renal-artery denervation as compared with a sham control. (Funded by Medtronic; SYMPLICITY HTN-3 ClinicalTrials.gov number, NCT01418261.).

High rates of non-adherence to antihypertensive treatment revealed by high-performance liquid chromatography-tandem mass spectrometry (HP LC-MS/MS) urine analysis

OBJECTIVES

Non-adherence to therapy is an important cause of suboptimal blood pressure control but few practical tools exist to accurately and routinely detect it. We used a simple urine-based assay to evaluate the prevalence of antihypertensive treatment non-adherence and its impact on blood pressure in a specialist hypertension centre.

METHODS

208 hypertensive patients (125 new referrals, 66 follow-up patients with inadequate blood pressure control and 17 renal denervation referrals) underwent assessment of antihypertensive drug intake using high-performance liquid chromatography-tandem mass spectrometry (HP LC-MS/MS) urine analysis at the time of clinical appointment. A total of 40 most commonly prescribed antihypertensive medications (or their metabolites) were screened for in spot urine samples.

RESULTS

Overall, 25% of patients were totally or partially non-adherent to antihypertensive treatment (total non-adherence 10.1%, partial non-adherence 14.9%). The highest prevalence of partial and total non-adherence was among follow-up patients with inadequate blood pressure control (28.8%) and those referred for consideration of renal denervation (23.5%), respectively. There was a linear relationship between blood pressure and the numerical difference in detected/prescribed antihypertensive medications-every unit increase in this difference was associated with 3.0 (1.1) mm Hg, 3.1 (0.7) mm Hg and 1.9 (0.7) mm Hg increase in adjusted clinic systolic blood pressure, clinic diastolic blood pressure (DBP) and 24 h mean daytime DBP (p=0.0051, p=8.62 × 10(-6), p=0.0057), respectively.

CONCLUSIONS

Non-adherence to blood pressure lowering therapy is common, particularly in patients with suboptimal blood pressure control and those referred for renal denervation. HP LC-MS/MS urine analysis could be used to exclude non-adherence and better stratify further investigations and intervention.