Catheter-based renal denervation in patients with uncontrolled hypertension in the absence of antihypertensive medications (SPYRAL HTN-OFF MED): a randomised, sham-controlled, proof-of-concept trial

New antihypertensive medications and clinical implications

Hypertension remains a global public health issue and is a leading preventable risk factor for many causes of mortality and morbidity. Although it is generally managed as an outpatient chronic disease, anaesthetists will inevitably encounter patients with hypertension, ranging from undiagnosed asymptomatic to chronic forms with end-organ damage(s). An understanding of perioperative management of anti-hypertensive pharmacotherapy is crucial. Although many drugs are familiar, new drug groups that have relevance for blood pressure control and perioperative care have evolved in recent years. This article also describes new antihypertensive agents currently available or under development that could impact perioperative management.

Renal Sympathetic Denervation in Patients with Resistant Hypertension: A Feasibility Study

Background/Aims

We assessed the feasibility of renal sympathetic denervation (RDN) treatment in patients with resistant hypertension using the Iberis® RDN system. This study was a prospective, multicenter, single-arm feasibility registry.

Methods

We collected data from patients who underwent RDN treatment using the Iberis system. From November 2014 to February 2016, 16 patients from 6 centers in Europe were enrolled in this registry.

Results

Consistent reductions in the 24-h systolic blood pressure (SBP) and diastolic blood pressure were obtained. At any follow-up point, more than 70% of the patients were responders. The change in the 24-h SBP at 1 month was strongly correlated with that at 12 months.

Conclusion

The Iberis system is safe and effective in patients for the treatment of resistant hypertension. Furthermore, our results suggest that we can estimate the effect of RDN in the long term at the 1-month follow-up point using the 24-h SBP.

Intravascular imaging, histopathological analysis, and catecholamine quantification following catheter-based renal denervation in a swine model: the impact of prebifurcation energy delivery

The purpose of this study was to evaluate the impact of prebifurcation renal denervation in a swine model and assess its safety through optical coherence tomography (OCT). Prebifurcation renal denervation with a multi-electrode catheter was performed in one renal artery of 12 healthy pigs, with the contralateral artery and kidney being used as controls. Angiograms and OCT pullbacks were obtained peri-procedurally and 1 month post procedure. Renal tissue catecholamines were quantified, and the arterial wall and peri-adventitial tissue were analyzed histologically. Intraluminal changes (endothelial swelling, spasm, and thrombus formation) were observed acutely by OCT in most of the treated arteries and were no longer visible at follow-up. Histology revealed a statistically significant accumulation of collagen (fibrosis) and a near absence of tyrosine hydroxylase labeling in the denervated artery, suggesting a clear reduction in nervous terminals. Renal tissue catecholamine levels were similar between both sides, probably due to the low number of ablation points and the renorenal reflex. The present study demonstrates that renal denervation is associated with acute intimal disruptions, areas of fibrosis, and a reduction in nervous terminals. The lack of difference in renal tissue catecholamine levels is indicative of the need to perform the highest and safest number of ablation points in both renal arteries. These findings are important because they demonstrate the histological consequences of radiofrequency energy application and its medium-term safety.

Advances in Clinical Cardiology 2017: A Summary of Key Clinical Trials

INTRODUCTION

Numerous important cardiology clinical trials have been published or presented at major international meetings during 2017. This paper aims to summarize these trials and place them in clinical context.

METHODS

The authors reviewed clinical trials presented at major cardiology conferences during 2017 including the American College of Cardiology, European Association for Percutaneous Cardiovascular Interventions, European Society of Cardiology, European Association for the Study of Diabetes, Transcatheter Cardiovascular Therapeutics, and the American Heart Association. Selection criteria were trials with a broad relevance to the cardiology community and those with potential to change current practice.

RESULTS

A total of 75 key cardiology clinical trials were identified for inclusion. New interventional and structural cardiology data include left main bifurcation treatment strategy, multivessel disease management in cardiogenic shock, drug-eluting balloons for in-stent restenosis, instantaneous wave-free physiological assessment, new-generation stents (COMBO, Orsiro), transcatheter aortic valve implantation, and closure devices. New preventative cardiology data include trials of liraglutide, empagliflozin, PCSK9 inhibitors (evolocumab and bococizumab), inclisiran, and anacetrapib. Antiplatelet data include the role of uninterrupted aspirin therapy during non-cardiac surgery and dual antiplatelet therapy following coronary artery bypass grafting. New data are also included from fields of heart failure (levosimendan, spironolactone), atrial fibrillation (apixaban in DC cardioversion), cardiac devices (closed loop stimulation pacing for neuromediated syncope), and electrophysiology (catheter ablation for atrial fibrillation).

CONCLUSION

This paper presents a summary of key clinical cardiology trials during the past year and should be of practical value to both clinicians and cardiology researchers.

Resistant Hypertension: Time to Consider the Best Fifth Anti-Hypertensive Treatment

PURPOSE OF REVIEW

Resistant hypertension (RH) is a growing clinical condition worldwide associated with target-organ damage and poor prognosis compared to non-resistant counterparts. The purpose of this review is to perform a critical evaluation of preferable drug choices for managing RH highlighting the evidence that significant proportion of patients remained uncontrolled despite using four anti-hypertensive drugs.

RECENT FINDINGS

Until recently, the fourth drug therapy was main derived from personal opinion or small interventional studies. The recent data derived from two multicentric randomized trials, namely PATHWAY-2 and ReHOT, pointed spironolactone as the preferable fourth drug therapy in patients with confirmed RH as compared to bisoprolol and doxazosin (PATHWAY-2) as well as clonidine (ReHOT). However, significant proportion of patients (especially observed in ReHOT trial that used 24-h ambulatory blood pressure monitoring) did not achieve optimal blood pressure with the fourth drug. This finding underscores the need of new approaches and treatment options in this important research area. The current evidence pointed that significant proportion of RH patients are requiring more than four drugs for controlling BP. This statement is particularly true considering the new criteria proposed by the 2017 Guidelines for diagnosing RH (> 130 × 80 mmHg). New combinations, drugs, or treatments should be tested aiming to reduce the RH burden. Based on the aforementioned multicentric trials, we proposed the first five preferable anti-hypertensive classes in the overall context of RH.

Attenuation of Splanchnic Autotransfusion Following Noninvasive Ultrasound Renal Denervation: A Novel Marker of Procedural Success

BACKGROUND

Renal denervation has no validated marker of procedural success. We hypothesized that successful renal denervation would reduce renal sympathetic nerve signaling demonstrated by attenuation of α-1-adrenoceptor-mediated autotransfusion during the Valsalva maneuver.

METHODS AND RESULTS

In this substudy of the Wave IV Study: Phase II Randomized Sham Controlled Study of Renal Denervation for Subjects With Uncontrolled Hypertension, we enrolled 23 subjects with resistant hypertension. They were randomized either to bilateral renal denervation using therapeutic levels of ultrasound energy (n=12) or sham application of diagnostic ultrasound (n=11). Within-group changes in autonomic parameters, office and ambulatory blood pressure were compared between baseline and 6 months in a double-blind manner. There was significant office blood pressure reduction in both treatment (16.1±27.3 mm Hg, P<0.05) and sham groups (27.9±15.0 mm Hg, P<0.01) because of which the study was discontinued prematurely. However, during the late phase II (Iii) of Valsalva maneuver, renal denervation resulted in substantial and significant reduction in mean arterial pressure (21.8±25.2 mm Hg, P<0.05) with no significant changes in the sham group. Moreover, there were significant reductions in heart rate in the actively treated group at rest (6.0±11.5 beats per minute, P<0.05) and during postural changes (supine 7.2±8.4 beats per minute, P<0.05, sit up 12.7±16.7 beats per minute, P<0.05), which were not observed in the sham group.

CONCLUSIONS

Blood pressure reduction per se is not necessarily a marker of successful renal nerve ablation. Reduction in splanchnic autotransfusion following renal denervation has not been previously demonstrated and denotes attenuation of (renal) sympathetic efferent activity and could serve as a marker of procedural success.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02029885.

Effect of renal denervation on blood pressure in the presence of antihypertensive drugs: 6-month efficacy and safety results from the SPYRAL HTN-ON MED proof-of-concept randomised trial

BACKGROUND

Previous catheter-based renal denervation studies have reported variable efficacy results. We aimed to evaluate safety and blood pressure response after renal denervation or sham control in patients with uncontrolled hypertension on antihypertensive medications with drug adherence testing.

METHODS

In this international, randomised, single-blind, sham-control, proof-of-concept trial, patients with uncontrolled hypertension (aged 20-80 years) were enrolled at 25 centres in the USA, Germany, Japan, UK, Australia, Austria, and Greece. Eligible patients had an office systolic blood pressure of between 150 mm Hg and 180 mm Hg and a diastolic blood pressure of 90 mm Hg or higher; a 24 h ambulatory systolic blood pressure of between 140 mm Hg and 170 mm Hg at second screening; and were on one to three antihypertensive drugs with stable doses for at least 6 weeks. Patients underwent renal angiography and were randomly assigned to undergo renal denervation or sham control. Patients, caregivers, and those assessing blood pressure were masked to randomisation assignments. The primary efficacy endpoint was blood pressure change from baseline (measured at screening visit two), based on ambulatory blood pressure measurements assessed at 6 months, as compared between treatment groups. Drug surveillance was used to assess medication adherence. The primary analysis was done in the intention-to-treat population. Safety events were assessed through 6 months as per major adverse events. This trial is registered with ClinicalTrials.gov, number NCT02439775, and follow-up is ongoing.

FINDINGS

Between July 22, 2015, and June 14, 2017, 467 patients were screened and enrolled. This analysis presents results for the first 80 patients randomly assigned to renal denervation (n=38) and sham control (n=42). Office and 24 h ambulatory blood pressure decreased significantly from baseline to 6 months in the renal denervation group (mean baseline-adjusted treatment differences in 24 h systolic blood pressure -7·0 mm Hg, 95% CI -12·0 to -2·1; p=0·0059, 24 h diastolic blood pressure -4·3 mm Hg, -7·8 to -0·8; p=0.0174, office systolic blood pressure -6·6 mm Hg, -12·4 to -0·9; p=0·0250, and office diastolic blood pressure -4·2 mm Hg, -7·7 to -0·7; p=0·0190). The change in blood pressure was significantly greater at 6 months in the renal denervation group than the sham-control group for office systolic blood pressure (difference -6·8 mm Hg, 95% CI -12·5 to -1·1; p=0·0205), 24 h systolic blood pressure (difference -7·4 mm Hg, -12·5 to -2·3; p=0·0051), office diastolic blood pressure (difference -3·5 mm Hg, -7·0 to -0·0; p=0·0478), and 24 h diastolic blood pressure (difference -4·1 mm Hg, -7·8 to -0·4; p=0·0292). Evaluation of hourly changes in 24 h systolic blood pressure and diastolic blood pressure showed blood pressure reduction throughout 24 h for the renal denervation group. 3 month blood pressure reductions were not significantly different between groups. Medication adherence was about 60% and varied for individual patients throughout the study. No major adverse events were recorded in either group.

INTERPRETATION

Renal denervation in the main renal arteries and branches significantly reduced blood pressure compared with sham control with no major safety events. Incomplete medication adherence was common.

FUNDING

Medtronic.

Endovascular ultrasound renal denervation to treat hypertension (RADIANCE-HTN SOLO): a multicentre, international, single-blind, randomised, sham-controlled trial

BACKGROUND

Early studies suggest that radiofrequency-based renal denervation reduces blood pressure in patients with moderate hypertension. We investigated whether an alternative technology using endovascular ultrasound renal denervation reduces ambulatory blood pressure in patients with hypertension in the absence of antihypertensive medications.

METHODS

RADIANCE-HTN SOLO was a multicentre, international, single-blind, randomised, sham-controlled trial done at 21 centres in the USA and 18 in Europe. Patients with combined systolic-diastolic hypertension aged 18-75 years were eligible if they had ambulatory blood pressure greater than or equal to 135/85 mm Hg and less than 170/105 mm Hg after a 4-week discontinuation of up to two antihypertensive medications and had suitable renal artery anatomy. Patients were randomised (1:1) to undergo renal denervation with the Paradise system (ReCor Medical, Palo Alto, CA, USA) or a sham procedure consisting of renal angiography only. The randomisation sequence was computer generated and stratified by centres with randomised blocks of four or six and permutation of treatments within each block. Patients and outcome assessors were blinded to randomisation. The primary effectiveness endpoint was the change in daytime ambulatory systolic blood pressure at 2 months in the intention-to-treat population. Patients were to remain off antihypertensive medications throughout the 2 months of follow-up unless specified blood pressure criteria were exceeded. Major adverse events included all-cause mortality, renal failure, an embolic event with end-organ damage, renal artery or other major vascular complications requiring intervention, or admission to hospital for hypertensive crisis within 30 days and new renal artery stenosis within 6 months. This study is registered with ClinicalTrials.gov, number NCT02649426.

FINDINGS

Between March 28, 2016, and Dec 28, 2017, 803 patients were screened for eligibility and 146 were randomised to undergo renal denervation (n=74) or a sham procedure (n=72). The reduction in daytime ambulatory systolic blood pressure was greater with renal denervation (-8·5 mm Hg, SD 9·3) than with the sham procedure (-2·2 mm Hg, SD 10·0; baseline-adjusted difference between groups: -6·3 mm Hg, 95% CI -9·4 to -3·1, p=0·0001). No major adverse events were reported in either group.

INTERPRETATION

Compared with a sham procedure, endovascular ultrasound renal denervation reduced ambulatory blood pressure at 2 months in patients with combined systolic-diastolic hypertension in the absence of medications.

FUNDING

ReCor Medical.

Targeted afferent renal denervation reduces arterial pressure but not renal inflammation in established DOCA-salt hypertension in the rat

Recent preclinical studies show renal denervation (RDNx) may be an effective treatment for hypertension; however, the mechanism remains unknown. We have recently reported total RDNx (TRDNx) and afferent-selective RDNx (ARDNx) similarly attenuated the development of deoxycorticosterone acetate (DOCA)-salt hypertension. Whereas TRDNx abolished renal inflammation, ARDNx had a minimal effect despite an identical antihypertensive effect. Although this study established that ARDNx attenuates the development of DOCA-salt hypertension, it is unknown whether this mechanism remains operative once hypertension is established. The current study tested the hypothesis that TRDNx and ARDNx would similarly decrease mean arterial pressure (MAP) in the DOCA-salt hypertensive rat, and only TRDNx would mitigate renal inflammation. After 21 days of DOCA-salt treatment, male Sprague-Dawley rats underwent TRDNx ( n = 16), ARDNx ( n = 16), or Sham ( n = 14) treatment and were monitored for 14 days. Compared with baseline, TRDNx and ARDNx decreased MAP similarly (TRDNx -14 ± 4 and ARDNx -15 ± 6 mmHg). After analysis of diurnal rhythm, rhythm-adjusted mean and amplitude of night/day cycle were also reduced in TRDNx and ARDNx groups compared with Sham. Notably, no change in renal inflammation, injury, or function was detected with either treatment. We conclude from these findings that: 1) RDNx mitigates established DOCA-salt hypertension; 2) the MAP responses to RDNx are primarily mediated by ablation of afferent renal nerves; and 3) renal nerves do not contribute to the maintenance of renal inflammation in DOCA-salt hypertension.

Blood Pressure and Renal Responses to Orthostatic Stress Before and After Radiofrequency Renal Denervation in Patients with Resistant Hypertension

Background/Aims

In patients with resistant hypertension, renal denervation (RDN) studies have mainly focused their outcomes on blood pressure (BP). The aim of this study was to evaluate the long-term effect of RDN on neurohormonal profiles, renal hemodynamics and sodium excretion in a resting state and during stress induced by lower body negative pressure (LBNP).

Materials and methods

This was a single center prospective observational study. Norepinephrine, plasma renin activity (PRA), glomerular filtration rate (GFR), renal plasma flow (RPF) and sodium excretion were measured in unstimulated conditions (rest) and after one hour of LBNP at three different time points: before (M0), one (M1) and twelve months (M12) after RDN.

Results

Thirteen patients with resistant hypertension were included. In the resting state, no differences were observed in norepinephrine, PRA, sodium excretion and mean BP levels after RDN. GFR (78 ± 32 ml/min at M0 vs 66 ± 26 ml/min at M12 (p = 0.012) and filtration fraction (22.6 ±5.4% at M0 vs 15.1 ±5.3% at M12 (p = 0.002)) both decreased after RDN. During LBNP, the magnitude of the mean BP increase was reduced from +6.8 ± 6.6 mm Hg at M0 to +2.3 ± 1.3 mm Hg at M12 (p = 0.005). The LBNP-induced increase in norepinephrine and decrease in GFR and sodium excretion observed before RDN were blunted after the procedure.

Conclusion

A decrease in GFR and filtration fraction was observed one year after RDN. In addition, our results suggest that RDN blunts not only the norepinephrine but also the mean BP, the GFR and the sodium excretion responses to an orthostatic stress one year after the intervention.

Registry number

NCT01734096

Selective vs. Global Renal Denervation: a Case for Less Is More

PURPOSE OF REVIEW

Review the renal nerve anatomy and physiology basics and explore the concept of global vs. selective renal denervation (RDN) to uncover some of the fundamental limitations of non-targeted renal nerve ablation and the potential superiority of selective RDN.

RECENT FINDINGS

Recent trials testing the efficacy of RDN showed mixed results. Initial investigations targeted global RDN as a therapeutic goal. The repeat observation of heterogeneous response to RDN including non-responders with lack of a BP reduction, or even more unsettling, BP elevations after RDN has raised concern for the detrimental effects of unselective global RDN. Subsequent studies have suggested the presence of a heterogeneous fiber population and the potential utility of renal nerve stimulation to identify sympatho-stimulatory fibers or "hot spots." The recognition that RDN can produce heterogeneous afferent sympathetic effects both change therapeutic goals and revitalize the potential of therapeutic RDN to provide significant clinical benefits. Renal nerve stimulation has emerged as potential tool to identify sympatho-stimulatory fibers, avoid sympatho-inhibitory fibers, and thus guide selective RDN.

Resistant hypertension: Renal denervation or intensified medical treatment?

Resistant hypertension (RH) can be diagnosed if blood pressure (BP) is not controlled with the combination of three antihypertensive drugs, including a diuretic, all at effective doses. Patients affected by this condition exhibit a marked increase in the risk of cardiovascular and renal morbid and fatal events. They also exhibit an increased activity of the sympathetic nervous system which is likely to importantly contribute at the renal and other vascular levels to the hypertensive state. Almost 10years ago renal denervation (RDN) by radiofrequency thermal energy delivery to the walls of the renal arteries was proposed for the treatment of RH. Several uncontrolled studies initially reported that this procedure substantially reduced the elevated BP values but this conclusion has not been supported by a recent randomized control trial, which has almost marginalized this therapeutic approach. A revival, however, is under way because of recent positive findings and technical improvement that hold promise to make renal denervation more complete. The antihypertensive efficacy and overall validity of RDN will have to be tested against drug treatment of RH. Several studies indicate that an excess of aldosterone production contributes to RH and recent evidence documents indisputably that anti-aldosterone agents such as spironolactone can effectively control BP in many RH patients, although with some side effects that require close patients' monitoring. At present, it is advisable to treat RH with the addition of an anti-aldosterone agent. If BP control is not achieved or serious side effects become manifest RDN may then be considered.

Erythrocyte Salt Sedimentation Assay Does Not Predict Response to Renal Denervation

Renal denervation (RDN) has recently been shown to be effective in patients without antihypertensive medication. However, about 30% of patients do not respond to RDN, and therefore, there exists a need to find predictors of response. Individuals are either salt-sensitive (SS) or non-salt-sensitive (NSS) in terms of their blood pressure (BP) regulation. The sympathetic nervous system can influence water and salt handling. RDN reduces sympathetic drive and has an impact on salt excretion. The present study was conducted to test the influence of salt sensitivity in terms of the BP reducing effect after RDN procedure. Salt sensitivity was estimated using the in vitro Erythrocyte Salt Sedimentation Assay (ESS). In 88 patients with resistant hypertension, RDN was performed. Office BP and lab testing were performed at baseline and at month 1, 3, 6, 12, 18, and 24 after RDN. A responder rate of 64.7% has been observed. Salt sensitivity measurements (ESS-Test) were completed in a subgroup of 37 patients with resistant hypertension. In this group, 15 were SS and 17 were salt-resistant according to the in vitro assay, respectively. The responder rate was 60% in SS patients and 59.1% in NSS patients, respectively. Electrolytes as well as aldosterone and renin levels did not differ between the two groups at baseline and in the follow-up measurements. The present study showed that salt sensitivity, estimated using the ESS in vitro test, did not affect the outcome of RDN and, therefore, does not help to identify patients suitable for RDN.

Role of the Sympathetic Nervous System and Its Modulation in Renal Hypertension

The kidneys are densely innervated with renal efferent and afferent nerves to communicate with the central nervous system. Innervation of major structural components of the kidneys, such as blood vessels, tubules, the pelvis, and glomeruli, forms a bidirectional neural network to relay sensory and sympathetic signals to and from the brain. Renal efferent nerves regulate renal blood flow, glomerular filtration rate, tubular reabsorption of sodium and water, as well as release of renin and prostaglandins, all of which contribute to cardiovascular and renal regulation. Renal afferent nerves complete the feedback loop via central autonomic nuclei where the signals are integrated and modulate central sympathetic outflow; thus both types of nerves form integral parts of the self-regulated renorenal reflex loop. Renal sympathetic nerve activity (RSNA) is commonly increased in pathophysiological conditions such as hypertension and chronic- and end-stage renal disease. Increased RSNA raises blood pressure and can contribute to the deterioration of renal function. Attempts have been made to eliminate or interfere with this important link between the brain and the kidneys as a neuromodulatory treatment for these conditions. Catheter-based renal sympathetic denervation has been successfully applied in patients with resistant hypertension and was associated with significant falls in blood pressure and renal protection in most studies performed. The focus of this review is the neural contribution to the control of renal and cardiovascular hemodynamics and renal function in the setting of hypertension and chronic kidney disease, as well as the specific roles of renal efferent and afferent nerves in this scenario and their utility as a therapeutic target.

Renal Nerve Stimulation as Procedural End Point for Renal Sympathetic Denervation

PURPOSE OF REVIEW

Renal sympathetic denervation (RDN) as treatment option for hypertension has a strong rationale; however, variable effects on blood pressure (BP) have been reported ranging from non-response to marked reductions in BP. The absence of a procedural end point for RDN is one of the potential factors associated with the variable response. Studies have suggested the use of renal nerve stimulation (RNS) to adequately address this issue. This review aims to provide an overview of the clinical and experimental data available regarding the effects of RNS in the setting of RDN.

RECENT FINDINGS

Animal studies have shown that high-frequency electrical stimulation of the sympathetic nerves in the adventitia of the renal arteries elicits an increase in BP and leads to an increased norepinephrine spillover as a marker of increased sympathetic activity and these effects of stimulation were attenuated or blunted after RDN. In a human feasibility study using RNS both before and after RDN, similar BP responses were observed. Moreover, in patients with resistant hypertension, RNS-induced changes in BP appeared to be correlated with 24-h BP response after RDN. These data suggest that RNS is a useful tool to identify renal sympathetic nerve fibers in patients with treatment-resistant hypertension undergoing RDN, and to predict the likely effectiveness of RDN treatments. In acute procedural settings both in animal and human models, RNS elicits increase in BP and HR before RDN and these effects are blunted after RDN. Up to now, there is preliminary evidence that the RNS-induced BP changes predict 24-h ABPM outcome at follow-up in patients with resistant hypertension. Of note, studies are small sized and results of large trials comparing conventional RDN to RNS-guided RDN are warranted.

Resistant Hypertension: Which Agent?

Resistant hypertension is commonly defined as office blood pressure above recommended target despite the use of optimal doses of at least three antihypertensive drugs including a diuretic. Australian guidelines recommend combination of blockers of the renin-angiotensin system, either ACE inhibitors or angiotensin receptor blockers, with calcium channel blockers and diuretics as the preferred triple therapy. A substantial proportion of hypertensive patients will require additional pharmacotherapy to achieve or get close to target blood pressure levels. Here we briefly review the evidence currently available to provide guidance on the most appropriate choice for additional antihypertensive pharmacotherapy and touch on interventional approaches that may be considered in some patients.

Renal sympathetic denervation restores aortic distensibility in patients with resistant hypertension: data from a multi-center trial

Renal sympathetic denervation (RDN) is under investigation as a treatment option in patients with resistant hypertension (RH). Determinants of arterial compliance may, however, help to predict the BP response to therapy. Aortic distensibility (AD) is a well-established parameter of aortic stiffness and can reliably be obtained by CMR. This analysis sought to investigate the effects of RDN on AD and to assess the predictive value of pre-treatment AD for BP changes. We analyzed data of 65 patients with RH included in a multicenter trial. RDN was performed in all participants. A standardized CMR protocol was utilized at baseline and at 6-month follow-up. AD was determined as the change in cross-sectional aortic area per unit change in BP. Office BP decreased significantly from 173/92 ± 24/16 mmHg at baseline to 151/85 ± 24/17 mmHg (p < 0.001) 6 months after RDN. Maximum aortic areas increased from 604.7 ± 157.7 to 621.1 ± 157.3 mm² (p = 0.011). AD improved significantly by 33% from 1.52 ± 0.82 to 2.02 ± 0.93 × 10⁻³ mmHg⁻¹ (p < 0.001). Increase of AD at follow-up was significantly more pronounced in younger patients (p = 0.005) and responders to RDN (p = 0.002). Patients with high-baseline AD were significantly younger (61.4 ± 10.1 vs. 67.1 ± 8.4 years, p = 0.022). However, there was no significant correlation of baseline AD to response to RDN. AD is improved after RDN across all age groups. Importantly, these improvements appear to be unrelated to observed BP changes, suggesting that RDN may have direct effects on the central vasculature.

Anatomical and procedural determinants of ambulatory blood pressure lowering following catheter-based renal denervation using radiofrequency

BACKGROUND/PURPOSE

Catheter-based renal sympathetic denervation (RDN) has been introduced to lower blood pressure (BP) and sympathetic activity in patients with uncontrolled hypertension with at best equivocal results. It has been postulated that anatomic and procedural elements introduce unaccounted variability and yet little is known of the impact of renal anatomy and procedural parameters on BP response to RDN.

METHODS/MATERIALS

Anatomical parameters such as length and diameter were analyzed by quantitative vascular analysis and the prevalence of accessory renal arteries and renal artery disease were documented in 150 patients with resistant hypertension undergoing bilateral RDN using a mono-electrode radiofrequency catheter (Symplicity Flex, Medtronic).

RESULTS

Accessory renal arteries and renal artery disease were present in 56 (37%) and 14 patients (9%), respectively. At 6-months, 24 h-ambulatory BP was reduced by 11/6 mm Hg (p < 0.001 for both). Change of systolic blood pressure (SBP) was not related to the presence of accessory renal arteries (p = 0.543) or renal artery disease (p = 0.598). Patients with at least one main renal artery diameter ≤ 4 mm had a more pronounced reduction of 24 h-ambulatory SBP compared to patients where both arteries were >4 mm (-19 vs. -10 mmHg; p = 0.038). Neither the length of the renal artery nor the number of RF ablations influenced 24 h-ambulatory BP reduction at 6 months.

CONCLUSIONS

24 h-ambulatory BP lowering was most pronounced in patients with smaller renal artery diameter but not related to renal artery length, accessory arteries or renal artery disease. Further, there was no dose-response relationship observed with increasing number of ablations.

CONDENSED ABSTRACT

Because little is known of the impact of renal anatomy and procedural parameters on blood pressure (BP) response to renal denervation (RDN), anatomical and procedural data were analyzed in 150 patients undergoing bilateral RDN. BP lowering was most pronounced in patients with smaller renal artery diameter but not related to renal artery length, the presence of renal artery disease or accessory renal arteries. Further, there was no dose-response relationship observed with increasing number of ablations.

Treatment of atrial fibrillation in patients with enhanced sympathetic tone by pulmonary vein isolation or pulmonary vein isolation and renal artery denervation: clinical background and study design : The ASAF trial: ablation of sympathetic atrial fibrillation

BACKGROUND

Hypertension is an important, modifiable risk factor for the development of atrial fibrillation (AF). Even after pulmonary vein isolation (PVI), 20-40% experience recurrent AF. Animal studies have shown that renal denervation (RDN) reduces AF inducibility. One clinical study with important limitations suggested that RDN additional to PVI could reduce recurrent AF.

OBJECTIVE

The goal of this multicenter randomized controlled study is to investigate whether RDN added to PVI reduces AF recurrence.

METHODS

The main end point is the time until first AF recurrence according to EHRA guidelines after a blanking period of 3 months. Assuming a 12-month accrual period and 12 months of follow-up, a power of 0.80, a two-sided alpha of 0.05 and an expected drop-out of 10% per group, 69 patients per group are required. We plan to randomize a total of 138 hypertensive patients with AF and signs of sympathetic overdrive in a 1:1 fashion. Patients should use at least two antihypertensive drugs. Sympathetic overdrive includes obesity, exercise-induced excessive blood pressure (BP) increase, significant white coat hypertension, hospital admission or fever induced AF, tachycardia induced AF and diabetes mellitus. The interventional group will undergo PVI + RDN and the control group will undergo PVI.

RESULTS

Patients will have follow-up for 1 year, and continuous loop monitoring is advocated.

CONCLUSION

This randomized, controlled study will elucidate if RDN on top of PVI reduces AF recurrence.

Modulation of renal sympathetic innervation: recent insights beyond blood pressure control

Renal afferent and efferent sympathetic nerves are involved in the regulation of blood pressure and have a pathophysiological role in hypertension. Additionally, several conditions that frequently coexist with hypertension, such as heart failure, obstructive sleep apnea, atrial fibrillation, renal dysfunction, and metabolic syndrome, demonstrate enhanced sympathetic activity. Renal denervation (RDN) is an approach to reduce renal and whole body sympathetic activation. Experimental models indicate that RDN has the potential to lower blood pressure and prevent cardio-renal remodeling in chronic diseases associated with enhanced sympathetic activation. Studies have shown that RDN can reduce blood pressure in drug-naïve hypertensive patients and in hypertensive patients under drug treatment. Beyond its effects on blood pressure, sympathetic modulation by RDN has been shown to have profound effects on cardiac electrophysiology and cardiac arrhythmogenesis. RDN can display anti-arrhythmic effects in a variety of animal models for atrial fibrillation and ventricular arrhythmias. The first non-randomized studies demonstrate that RDN may promote the maintenance of sinus rhythm following catheter ablation in patients with atrial fibrillation. Registry data point towards a beneficial effect of RDN to prevent ventricular arrhythmias in patients with heart failure and electrical storm. Further large randomized placebo-controlled trials are needed to confirm the antihypertensive and anti-arrhythmic effects of RDN. Here, we will review the current literature on anti-arrhythmic effects of RDN with the focus on atrial fibrillation and ventricular arrhythmias. We will discuss new insights from preclinical and clinical mechanistic studies and possible clinical implications of RDN.

Role of afferent and efferent renal nerves in the development of AngII-salt hypertension in rats

Hypertension is the leading modifiable risk factor for death worldwide, yet the causes remain unclear and treatment remains suboptimal. Catheter-based renal denervation (RDNX) is a promising new treatment for resistant hypertension, but the mechanisms underlying its antihypertensive effect remain unclear. We recently found that RDNX attenuates deoxycorticosterone acetate-salt hypertension and that this is dependent on ablation of afferent renal nerves and is associated with decreased renal inflammation. To determine if this is common to other models of salt-sensitive hypertension, rats underwent complete RDNX (n = 8), selective ablation of afferent renal nerves (n = 8), or sham denervation (n = 8). Mean arterial pressure (MAP) and heart rate were measure by telemetry and rats were housed in metabolic cages for measurement of sodium and water balance. Rats were then subjected to angiotensin II (AngII)-salt hypertension (10 ng/kg/min, intravenous + 4% NaCl diet) for 2 weeks. At the end of the study, renal T-cell infiltration was quantified by flow cytometry. AngII resulted in an increase in MAP of ~50 mmHg in all three groups with no between group differences, and a transient bradycardia that was blunted by selective ablation of afferent renal nerves. Sodium and water balance were unaffected by AngII-salt treatment and similar between groups. Lastly, AngII infusion was not associated with T-cell infiltration into the kidneys, and T-cell counts were unaffected by the denervation procedures. These results suggest that AngII-salt hypertension in the rat is not associated with renal inflammation and that neither afferent nor efferent renal nerves contribute to this model.