Renal artery sympathetic denervation: observations from the UK experience

Skin sodium content as a predictor of blood pressure response to renal denervation

Patients with treatment resistant hypertension (TRH) are known to have elevated sodium (Na) content in muscle and skin. Renal denervation (RDN) emerged as an adjacent therapeutic option in this group of patients. This analysis aimed at evaluating whether tissue Na content predicts blood pressure (BP) response after RDN in patients with TRH. Radiofrequency-device based RDN was performed in 58 patients with uncontrolled TRH. Office and 24-h ambulatory BP were measured at baseline and after 6 months. To assess tissue Na content Na magnetic resonance imaging (Na-MRI) was performed at baseline prior to RDN. We splitted the study cohort into responders and non-responders based on the median of systolic 24-h ambulatory blood pressure (ABP) reduction after 6 months and evaluated the association between BP response to RDN and tissue Na content in skin and muscle. The study was registered at http://www.clinicaltrials.gov (NCT01687725). Six months after RDN 24-h ABP decreased by -8.6/-4.7 mmHg. BP-Responders were characterized by the following parameters: low tissue sodium content in the skin (p = 0.040), female gender (p = 0.027), intake of aldosterone antagonists (p = 0.032), high baseline 24-h night-time heart rate (p = 0.045) and high LDL cholesterol (p < 0.001). These results remained significant after adjustment for baseline 24-h systolic BP. Similar results were obtained when the median of day-time and night-time ABP reduction after 6 months were used as cut-off criteria for defining BP response to RDN. We conclude that in addition to clinical factors including baseline 24-h ABP Na-MRI may assist to select patients with uncontrolled TRH for RDN treatment.

New data, new studies, new hopes for renal denervation in patients with uncontrolled hypertension

Background

following the publication of SYMPLICITY HTN-3 the field of renal of denervation was put on hold. Although SYMPLICITY HTN-3 was well-designed and sham-controlled trial it failed to show any meaningful reduction in office or 24 h ambulatory blood pressure. The procedure was however safe and allowed research to continue. Although several pitfalls of the study have been pointed out, incomplete renal denervation was also implicated. Since then, a great deal of basic and clinical research took place and will be briefly commented on in this article.

Methods and results

Before and after SYMPLICITY-HTN-3, numerous uncontrolled, single or unblinded studies have shown substantial office BP reduction ranging from -7.7 to -32 mmHg and ambulatory BP ranging from -2.2 to 10.2 mmHg. Average weighted office systolic BP reduction was -20.8 mmHg and weighted average 24 h ambulatory BPM reduction was -7.8 mmHg. National and international registries have shown similar BP reductions, but results remained unconvincing due to lack of reliable sham controls. In recent years, 5 well-designed sham - controlled studies (beyond, SYMPLICITY-HTN-3) have been published. Of those studies two were single center and three were multicenter international studies. Four studies used single tip or multi-electrode, radiofrequency catheters and one used focused ultrasound. The three multicenter studies reported positive-placebo subtracted results and established BP reductions measured both in the office and by ambulatory monitoring. No serious adverse events were reported.

Conclusions

It can therefore be concluded that the latest sham controlled studies established efficacy and safety of renal denervation.

Joint UK societies' 2019 consensus statement on renal denervation

Improved and durable control of hypertension is a global priority for healthcare providers and policymakers. There are several lifestyle measures that are proven to result in improved blood pressure (BP) control. Moreover, there is incontrovertible evidence from large scale randomised controlled trials (RCTs) that antihypertensive drugs lower BP safely and effectively in the long-term resulting in substantial reduction in cardiovascular morbidity and mortality. Importantly, however, evidence is accumulating to suggest that patients neither sustain long-term healthy behaviours nor adhere to lifelong drug treatment regimens and thus alternative measures to control hypertension warrant further investigation. Endovascular renal denervation (RDN) appears to hold some promise as a non-pharmacological approach to lowering BP and achieves renal sympathectomy using either radiofrequency energy or ultrasound-based approaches. This treatment modality has been evaluated in clinical trials in humans since 2009 but initial studies were compromised by being non-randomised, without sham control and small in size. Subsequently, clinical trial design and rigour of execution has been greatly improved resulting in recent sham-controlled RCTs that demonstrate short-term reduction in ambulatory BP without any significant safety concerns in both medication-naïve and medication-treated hypertensive patients. Despite this, the joint UK societies still feel that further evaluation of this therapy is warranted and that RDN should not be offered to patients outside of the context of clinical trials. This document reviews the updated evidence since our last consensus statement from 2014 and provides a research agenda for future clinical studies.

Renal denervation for the treatment of resistant hypertension in Spain. The Flex-Spyral Registry

INTRODUCTION AND OBJECTIVES

Renal denervation is a percutaneous intervention for the treatment of resistant hypertension. Randomized studies have shown contradictory results on its efficacy. We present the results of a renal denervation registry for the treatment of resistant hypertension in real-life patients in Spain.

METHODS

Multicenter registry of consecutive patients with resistant hypertension treated with renal denervation in Spain between 2009 and 2018.

RESULTS

We included 125 patients (mean age, 56 years; 41% female; mean onset of hypertension 14±9 years previously). Office systolic and diastolic blood pressure and ambulatory blood pressure monitoring decreased 6 months after the intervention (166±20/95±16 to 149±22/87±16 mmHg and 151±14/89±12 to 143±15/84±11, both P <.0001). At 12 months, the blood pressure reduction was maintained and the number of antihypertensive drugs decreased from 4.9±1.2 to 4.4±1.5 (P=.0001). There were no significant procedure-related complications. The response rate to denervation at 1 year was 80%, but there were wide differences between centers.

CONCLUSIONS

In patients with resistant hypertension, treatment with renal denervation was related to a decrease in office blood pressure and, more importantly, in ambulatory blood pressure monitoring, with a significant reduction in pharmacological treatment.

Procedural and anatomical predictors of renal denervation efficacy using two radiofrequency renal denervation catheters in a porcine model

Introduction:

Several renal denervation (RDN) systems are currently under investigation for treatment of hypertension by ablation of renal sympathetic nerves. The procedural efficacy of devices, however, is variable and incompletely understood. This study aimed at investigating procedural and anatomical predictors of RDN efficacy by comparing two radiofrequency catheter systems in a porcine model.

Methods:

Domestic swine were assigned into two treatment groups (n = 10) and one sham group (n = 3). Bilateral RDN in main and in branch segments of renal arteries was performed using two different multielectrode catheter systems [Symplicity Spyral (SPY) and IberisBloom (IBB)]. After 7 days, measurement of norepinephrine (NEPI) tissue concentrations and histological analyses have been performed.

Results:

Renal NEPI tissue concentration following RDN was significantly reduced when compared with Sham (SPY: −95 ± 3% vs. Sham, P < 0.001; IBB: −88 ± 11% vs. Sham, P < 0.001). Histological evaluation showed comparable lesion depth and lesion area (lesion depth: SPY-main 6.26 ± 1.62 mm vs. SPY-branch 3.49 ± 1.11 mm; IBB-main 5.93 ± 1.88 mm vs. IBB-branch: 3.26 ± 1.26 mm, P < 0.001; lesion area: SPY-main 43.5 ± 29.5 mm² vs. SYP-branch 45.0 ± 38.0 mm²; IBB-main 52.3 ± 34.8 mm² vs. IBB-branch 44.0 ± 42.6 mm², P = 0.77; intergroup SPY vs. IBB, P = 0.73). Histological investigations documented a significant correlation between number of ablations per millimeter length of renal artery and reduction in NEPI tissue concentration.

Conclusion:

The two devices under investigation demonstrated similar histopathological lesion characteristics and similar reduction of renal NEPI levels. An increase in number of ablations per millmeter length of renal artery resulted in improved efficacy and reduced variability in treatment effects.

Renal Denervation: Is It Ready for Prime Time?

PURPOSE OF REVIEW

Interventional cardiology and in particular the field of renal denervation is subject to constant change. This review provides an up to date overview of renal denervation trials and an outlook on what to expect in the future.

RECENT FINDINGS

After the sham-controlled SYMPLICITY HTN-3 trial dampened the euphoria following early renal denervation trials, the recently published results of the sham-controlled SPYRAL HTN and RADIANCE HTN trials provided proof-of-principle for the blood pressure-lowering efficacy of renal denervation. However, these studies underline the major issue of patients' non-adherence to antihypertensive medication as well as the need for reliable patient- and procedure-related predictors of response. The second generation of sham-controlled renal denervation trials provided proof of principle for the blood pressure-lowering efficacy of RDN. However, larger trials have to assess long-term safety and efficacy.

Renal sympathetic denervation for treatment of hypertension: where are we now in 2019?

PURPOSE OF REVIEW

Although sound physiological principles and surgical precedent underpin renal denervation as a therapy for treatment resistant hypertension, and early clinical studies had produced encouraging results, the first sham-controlled study (SYMPLICITY HTN-3) failed to achieve its primary efficacy endpoint. Lessons learnt from this trial, and the knowledge derived from further animal and autopsy work, have been applied in three recently published sham-controlled trials.

RECENT FINDINGS

These trials - SPYRAL OFF-MED, RADIANCE SOLO and SPYRAL ON-MED - using newer technologies, demonstrate a 5-10 mmHg incremental reduction in ambulatory SBP from RDN against sham-control, in patients with mild-to-moderate hypertension taking 0-3 drugs.

SUMMARY

These results provide proof of principle of the blood pressure-lowering effect of renal denervation. We now require data on long-term safety and durability of the procedure. Research is needed to identify predictive markers of response as about one-third of individuals do not respond to renal denervation. Hard-outcome data would be welcome but might be difficult to acquire. Individuals with treatment resistance are obvious treatment candidates, but RDN may also potentially benefit those with medication nonadherence and/or intolerance and those unwilling to take pills.

Renal Denervation in High-risk Patients with Hypertension

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Device-based Therapy for Hypertension

Hypertension continues to be a major contributor to global morbidity and mortality, fuelled by an abundance of patients with uncontrolled blood pressure despite the multitude of pharmacological options available. This may occur as a consequence of true resistant hypertension, through an inability to tolerate current pharmacological therapies, or non-adherence to antihypertensive medication. In recent years, there has been a rapid expansion of device-based therapies proposed as novel non-pharmacological approaches to treating resistant hypertension. In this review, we discuss seven novel devices—renal nerve denervation, baroreflex activation therapy, carotid body ablation, central iliac arteriovenous anastomosis, deep brain stimulation, median nerve stimulation, and vagal nerve stimulation. We highlight how the devices differ, the varying degrees of evidence available to date and upcoming trials. This review also considers the possible factors that may enable appropriate device selection for different hypertension phenotypes.

Blood pressure response to catheter-based renal sympathetic denervation in severe resistant hypertension: data from the Greek Renal Denervation Registry

BACKGROUND/INTRODUCTION

The efficacy of catheter-based renal sympathetic denervation (RDN) in terms of blood pressure (BP) reduction has been questioned, while "real-world" data from registries are needed. In this study, we report the complete set of 12-month data on office and ambulatory BP changes as well as the predictors for BP response to RDN from a national registry.

METHODS

In 4 Greek hospital centers, 79 patients with severe drug-resistant hypertension (age 59 ± 10 years, 53 males, body mass index 33 ± 5 kg/m2; office BP and 24-h ambulatory BP were 176 ± 15/95 ± 13 and 155 ± 14/90 ± 12 mmHg, respectively, 4.4 ± 0.9 antihypertensive drugs) underwent RDN and were followed-up for 12 months in the Greek Renal Denervation Registry. Bilateral RDN was performed using percutaneous femoral approach and standardized techniques.

RESULTS

Reduction in office systolic/diastolic BP at 6 and 12 months from baseline was -30/-12 and -29/-12 mmHg, while the reduction in 24-h ambulatory BP was -16/-9 and -15/-9 mmHg, respectively (p < 0.05 for all). Patients that were RDN responders (85%, n = 58), defined as an at least 10-mmHg decrease in office systolic BP at 12 months, compared to non-responders were younger (57 ± 9 vs 65 ± 8 years, p < 0.05), had higher baseline office systolic BP (176 ± 17 vs 160 ± 11 mmHg, p < 0.05) and 24-h systolic BP (159 ± 13 vs 149 ± 11 mmHg, p < 0.05). Stepwise logistic regression analysis revealed that age, obesity parameters, and baseline office BP were independent predictors of RDN response (p < 0.05 for both), but not the type of RDN catheter or the use of aldosterone antagonists. At 12 months, there were no significant changes in renal function and any new serious device or procedure-related adverse events.

CONCLUSIONS

In our "real-world" multicenter national registry, the efficacy of renal denervation in reducing BP as well as safety is confirmed during a 12-month follow-up. Moreover, younger age, obesity, and higher levels of baseline systolic BP are independently related to better BP response to RDN.

Interventional procedures and future drug therapy for hypertension

Hypertension management poses a major challenge to clinicians globally once non-drug (lifestyle) measures have failed to control blood pressure (BP). Although drug treatment strategies to lower BP are well described, poor control rates of hypertension, even in the first world, suggest that more needs to be done to surmount the problem. A major issue is non-adherence to antihypertensive drugs, which is caused in part by drug intolerance due to side effects. More effective antihypertensive drugs are therefore required which have excellent tolerability and safety profiles in addition to being efficacious. For those patients who either do not tolerate or wish to take medication for hypertension or in whom BP control is not attained despite multiple antihypertensives, a novel class of interventional procedures to manage hypertension has emerged. While most of these target various aspects of the sympathetic nervous system regulation of BP, an additional procedure is now available, which addresses mechanical aspects of the circulation. Most of these new devices are supported by early and encouraging evidence for both safety and efficacy, although it is clear that more rigorous randomized controlled trial data will be essential before any of the technologies can be adopted as a standard of care.

Renal Denervation

Sympathetic nervous system over-activity is closely linked with elevation of systemic blood pressure. Both animal and human studies suggest renal sympathetic nerves play an important role in this respect. Historically, modulation of sympathetic activity has been used to treat hypertension. More recently, catheter based renal sympathetic denervation was introduced for the management of treatment resistant hypertension. Sound physiological principles and surgical precedent underpin renal denervation as a therapy for treatment of resistant hypertension. Encouraging results of early studies led to a widespread adoption of the procedure for management of this condition. Subsequently a sham controlled randomised controlled study failed to confirm the benefit of renal denervation leading to a halt in its use in most countries in the world. However, critical analysis of the sham-controlled study indicates a number of flaws. A number of lessons have been learnt from this and other studies which need to be applied in future trials to ascertain the actual role of renal denervation in the management of treatment resistant hypertension before further implementation. This chapter deals with all these issues in detail.

Renal denervation for treatment of ventricular arrhythmias: data from an International Multicenter Registry

INTRODUCTION

Ventricular arrhythmias (VAs) in patients with chronic heart failure (CHF) are sometimes refractory to antiarrhythmic drugs and cardiac ablation. This study aimed to investigate catheter-based renal sympathetic denervation (RDN) as antiarrhythmic strategy in refractory VA.

METHODS

These are the first data from a pooled analysis of 13 cases from five large international centers (age 59.2 ± 14.4 years, all male) with CHF (ejection fraction 25.8 ± 10.1 %, NYHA class 2.6 ± 1) presented with refractory VA who underwent RDN. Ventricular arrhythmias, ICD therapies, clinical status, and blood pressure (BP) were evaluated before and 1-12 months after RDN.

RESULTS

Within 4 weeks prior RDN, a median of 21 (interquartile range 10-30) ventricular tachycardia (VT) or fibrillation (VF) episodes occurred despite antiarrhythmic drugs and prior cardiac ablation. RDN was performed bilaterally with a total number of 12.5 ± 3.5 ablations and without peri-procedural complications. One and 3 months after RDN, VT/VF episodes were reduced to 2 (0-7) (p = 0.004) and 0 (p = 0.006), respectively. Four (31 %) and 11 (85 %) patients of these 13 patients were free from VA at 1 and 3 months. Although BP was low at baseline (116 ± 18/73 ± 13 mmHg), no significant changes of BP or NYHA class were observed after RDN. During follow-up, three patients died from non-rhythm-related causes.

CONCLUSIONS

In patients with CHF and refractory VA, RDN appears to be safe concerning peri-procedural complications and blood pressure changes, and is associated with a reduced arrhythmic burden.

Controversies Surrounding Renal Denervation: Lessons Learned From Real-World Experience in Two United Kingdom Centers

Renal denervation (RDN) is a therapy that targets treatment-resistant hypertension (TRH). The Renal Denervation in Patients With Uncontrolled Hypertension (Symplicity) HTN-1 and Symplicity HTN-2 trials reported response rates of >80%; however, sham-controlled Symplicity HTN-3 failed to reach its primary blood pressure (BP) outcome. The authors address the current controversies surrounding RDN, illustrated with real-world data from two centers in the United Kingdom. In this cohort, 52% of patients responded to RDN, with a 13±32 mm Hg reduction in office systolic BP (SBP) at 6 months (n=29, P=.03). Baseline office SBP and number of ablations correlated with office SBP reduction (R=-0.47, P=.01; R=-0.56, P=.002). RDN appears to be an effective treatment for some patients with TRH; however, individual responses are highly variable. Selecting patients for RDN is challenging, with only 10% (33 of 321) of the screened patients eligible for the study. Medication alterations and nonadherence confound outcomes. Adequate ablation is critical and should impact future catheter design/training. Markers of procedural success and improved patient selection parameters remain key research aims.