Comparison of standard renal denervation procedure versus novel distal and branch vessel procedure with brachial arterial access

Differences in the effectiveness and safety of different renal denervation devices

Renal denervation (RDN) is a minimally invasive, endovascular catheter-based procedure using radiofrequency, ultrasound, or alcohol-mediated ablation to treat resistant hypertension. RDN gained popularity in 2009 when it was shown to have an antihypertensive effect. However, concerns about the efficacy of RDN were raised in the HTN-3 trial published in 2014, and the development of several RDN devices was then discontinued. In the process, new randomized controlled trials were conducted after the development of some of the RDN devices, the quality assurance of the procedure, changes in ablation points, and improvements in study design. In November 2023, the U.S. Food and Drug Administration approved a radiofrequency RDN device and an ultrasound RDN device. The results of a randomized controlled trial of an alcohol-mediated RDN device have been published, and future trends are being watched closely. In this mini-review, we summarize the differences in the antihypertensive effect and safety of the different RDN devices and the endpoints of the procedure in order to contribute to the further development of RDN devices Currently available renal denervation device. A multielectrode radiofrequency ablation (Spyral), (B) ultrasound denervation (Paraise), and (C) alcohol-mediated perivascular denervation (Peregrine). ASBP ambulatory systolic blood pressure, ADBP ambulatory diastolic blood pressure, OSBP office systolic blood pressure, ODBP office diastolic blood pressure. Analysis according to types of renal denervation device (radiofrequency, ultrasound, or alcohol-mediated device). P values for interaction were 0.578 (ambulatory SBP), 0.499 (ambulatory diastolic BP), 0.853 (office SBP), and 0.870 (office diastolic BP).

Renal denervation for resistant hypertension

BACKGROUND

Resistant hypertension is highly prevalent among the general hypertensive population and the clinical management of this condition remains problematic. Different approaches, including a more intensified antihypertensive therapy, lifestyle modifications or both, have largely failed to improve patients' outcomes and to reduce cardiovascular and renal risk. As renal sympathetic hyperactivity is a major driver of resistant hypertension, in the last decade renal sympathetic ablation (renal denervation) has been proposed as a possible therapeutic alternative to treat this condition.

OBJECTIVES

We sought to evaluate the short- and long-term effects of renal denervation in individuals with resistant hypertension on clinical end points, including fatal and non-fatal cardiovascular events, all-cause mortality, hospital admissions, quality of life, blood pressure control, left ventricular hypertrophy, cardiovascular and metabolic profile and kidney function, as well as the potential adverse events related to the procedure.

SEARCH METHODS

For this updated review, the Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to 3 November 2020: Cochrane Hypertension's Specialised Register, CENTRAL (2020, Issue 11), Ovid MEDLINE, and Ovid Embase. The World Health Organization International Clinical Trials Registry Platform (via CENTRAL) and the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov were searched for ongoing trials. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) that compared renal denervation to standard therapy or sham procedure to treat resistant hypertension, without language restriction.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed study risk of bias. We summarised treatment effects on available clinical outcomes and adverse events using random-effects meta-analyses. We assessed heterogeneity in estimated treatment effects using Chi² and I² statistics. We calculated summary treatment estimates as a mean difference (MD) or standardised mean difference (SMD) for continuous outcomes, and a risk ratio (RR) for dichotomous outcomes, together with their 95% confidence intervals (CI). Certainty of evidence has been assessed using the GRADE approach.

MAIN RESULTS

We found 15 eligible studies (1416 participants). In four studies, renal denervation was compared to sham procedure; in the remaining studies, renal denervation was tested against standard or intensified antihypertensive therapy. Most studies had unclear or high risk of bias for allocation concealment and blinding.  When compared to control, there was low-certainty evidence that renal denervation had little or no effect on the risk of myocardial infarction (4 studies, 742 participants; RR 1.31, 95% CI 0.45 to 3.84), ischaemic stroke (5 studies, 892 participants; RR 0.98, 95% CI 0.33 to 2.95), unstable angina (3 studies, 270 participants; RR 0.51, 95% CI 0.09 to 2.89) or hospitalisation (3 studies, 743 participants; RR 1.24, 95% CI 0.50 to 3.11). Based on moderate-certainty evidence, renal denervation may reduce 24-hour ambulatory blood pressure monitoring (ABPM) systolic BP (9 studies, 1045 participants; MD -5.29 mmHg, 95% CI -10.46 to -0.13), ABPM diastolic BP (8 studies, 1004 participants; MD -3.75 mmHg, 95% CI -7.10 to -0.39) and office diastolic BP (8 studies, 1049 participants; MD -4.61 mmHg, 95% CI -8.23 to -0.99). Conversely, this procedure had little or no effect on office systolic BP (10 studies, 1090 participants; MD -5.92 mmHg, 95% CI -12.94 to 1.10). Moderate-certainty evidence suggested that renal denervation may not reduce serum creatinine (5 studies, 721 participants, MD 0.03 mg/dL, 95% CI -0.06 to 0.13) and may not increase the estimated glomerular filtration rate (eGFR) or creatinine clearance (6 studies, 822 participants; MD -2.56 mL/min, 95% CI -7.53 to 2.42).  AUTHORS' CONCLUSIONS: In patients with resistant hypertension, there is low-certainty evidence that renal denervation does not improve major cardiovascular outomes and renal function. Conversely, moderate-certainty evidence exists that it may improve 24h ABPM and diastolic office-measured BP. Future trials measuring patient-centred instead of surrogate outcomes, with longer follow-up periods, larger sample size and more standardised procedural methods are necessary to clarify the utility of this procedure in this population.

Renal arteries denervation: from the treatment of resistant hypertension to the treatment of atrial fibrillation

Renal denervation (RDN) is a therapeutic strategy for patients with uncontrolled arterial hypertension characterized by considerable fluctuations during its progression. After initial strong enthusiasm, the procedure came to an abrupt halt following the publication of the Symplicity HTN-3 study results. The results of recently published studies highlight the reduction in blood pressure values after RDN and justify the inclusion in the Guidelines of new recommendations for the use of RDN in clinical practice, in selected patients. Additionally, RDN findings are summarized in view of other potential indications such as atrial fibrillation. Six prospective, randomized studies are presented that evaluated RDN as an adjunct therapy to pulmonary vein isolation for the treatment of atrial fibrillation. In five studies, patients had uncontrolled hypertension despite therapy with three antihypertensive drugs. The analysis of these studies showed that RDN reduced the recurrence of atrial fibrillation (AF) by 57% compared to patients with pulmonary vein isolation (PVI) only. Modulation of the autonomic nervous system by RDN has been shown not only to reduce blood pressure but also to have an antiarrhythmic effect in symptomatic AF patients when the strategy is combined with PVI, thus opening up new therapeutic scenarios.

The current status of renal denervation for the treatment of arterial hypertension

Despite the availability of safe and effective antihypertensive drugs, blood pressure (BP) control to guideline-recommended target values is poor. Several device-based therapies have been introduced to lower BP. The most extensively investigated approach is catheter-based renal sympathetic denervation (RDN), which aims to interrupt the activity of afferent and efferent renal sympathetic nerves by applying radiofrequency energy, ultrasound energy, or injection of alcohol in the perivascular space. The second generation of placebo-controlled trials have provided solid evidence for the BP-lowering efficacy of radiofrequency- and ultrasound-based RDN in patients with and without concomitant pharmacological therapy. In addition, the safety profile of RDN appears to be excellent in all registries and clinical trials. However, there remain unsolved issues to be addressed. This review summarizes the rationale as well as the current evidence and discusses open questions and possible future indications of catheter-based RDN.

Confounding Factors in Renal Denervation Trials: Revisiting Old and Identifying New Challenges in Trial Design of Device Therapies for Hypertension

Recent randomized sham-controlled trials have demonstrated significant blood pressure reductions following renal denervation (RDN) in patients with hypertension, both in the presence and absence of antihypertensive therapy. These new data encouraged us to revisit previously published insights into potential clinical trial confounding factors that informed the design and conduct of forthcoming trials. Initially identified confounders related to procedural technique, medication variability, and selected patient subgroups have been addressed in contemporary trial design. Regarding procedural method and technology, blood pressure reductions may be improved by ensuring circumferential lesion creation in the distal renal arteries and branch vessels. Safety of the RDN procedure has been demonstrated in multiple independent meta-analyses including thousands of treated patients with low reported rates of renal vessel complications and maintenance of renal function. However, a newer generation of RDN trials has also introduced insights related to medication adherence, patient selection, and the definition of treatment response. Evolving evidence indicates that RDN therapy may be considered in higher risk populations of uncontrolled hypertension regardless of ethnicity and in patients expressing a strong preference for a nondrug therapy option. Despite advances in procedural technique and clinical trial conduct, inconsistent antihypertensive-drug adherence behavior remains perhaps the most critical clinical trial design issue for device-based hypertension therapies. As the balance in clinical equipoise increasingly favors RDN, justification of sham-controlled trial designs will be revisited, and novel study designs may be required to evaluate the safety and efficacy of novel devices and procedures intended to address the escalating prevalence of poorly controlled hypertension.

Development and Evaluation of a Disease Large Animal Model for Preclinical Assessment of Renal Denervation Therapies

New-generation catheters-based renal denervation (RDN) is under investigation for the treatment of uncontrolled hypertension (HTN). We assessed the feasibility of a large animal model of HTN to accommodate the human RDN devices. Ten minipigs were instrumented to measure blood pressure (BP) in an awake-state. HTN was induced with subcutaneous 11-deoxycorticosterone (DOCA, 100 mg/kg) implants. Five months after, the surviving animals underwent RDN with the Symplicity^® system. Norepinephrine (NE) renal gradients were determined before and 1 month after RDN. Renal arteries were processed for histological (hematoxylin-eosin, Movat pentachrome) and immunohistochemical (S100, tyrosine-hydroxylase) analyses. BP significantly rose after DOCA implants. Six animals died prematurely, mainly from infectious causes. The surviving animals showed stable BP levels after 5 months. One month after RDN, nerve damage was showed in three animals, with impedance drop >10%, NE gradient drop and reduction in BP. The fourth animal showed no nerve damage, impedance drop <10%, NE gradient increase and no change in BP. In conclusion, the minipig model of DOCA-induced HTN is feasible, showing durable effects. High mortality should be addressed in next iterations of this model. RDN may partially offset the DOCA-induced HTN. Impedance drop and NE renal gradient could be markers of RDN success.

Safety and Efficacy of Transbrachial Access for Endovascular Procedures: A Single-Center Retrospective Analysis

BACKGROUND

Endovascular procedures nowadays are generally performed via the femoral and radial artery. Although not routinely used by many, there is still an essential role for vascular interventions via brachial access. The technological advancement of endovascular devices leads to a significant increase of the variety of percutaneously treatable vascular pathology. The brachial artery approach nowadays is becoming crucial for complex procedures either as single access or in the context of mandatory double vascular approach for many complex interventions.

OBJECTIVE

To evaluate the safety and efficacy of brachial artery access for diagnostic arteriography and endovascular interventions in different vascular territories in a single-center setting on the basis of a retrospective analysis of prospectively collected data in a large patient cohort.

METHODS

Between 01/2013 and 09/2016, 11,274 endovascular procedures were performed in our hospital, 847 (7.5%) of them via brachial access, presenting the database for this study. All demographic, clinical, and periprocedural data were obtained prospectively and included in the computerized hospital records, and on this basis, a retrospective analysis was performed.

RESULTS

While the radial access was the most used and constant for coronary and noncoronary interventions in our center (71%) in this period, the use of brachial access increased (from 4% to 12%) causing the femoral to decrease (from 27% to 16%). We used the brachial approach for diagnostic purposes in 162 patients (19%) and for head to toe endovascular interventions (including angioplasty, stenting, thrombolysis, or as adjunctive access) in 685 patients (81%). For 53 patients (6.2%), this was the only possible access for endovascular intervention. Overall access site-related complications occurred in 25 patients (2.9%), in 19 of them (2.2%) required surgical correction, for brachial artery thrombosis or pseudoaneurysm. The other six were managed conservatively. No permanent neurological deficits of the arm or severe bleeding were observed. Minor complications, mostly hematomas, occurred in 62 patients (7.3%), but they required no further treatment.

CONCLUSION

Brachial artery access expands our capability to perform complex procedures by allowing us to reach arterial targets in all territories. Complications of brachial vascular access are gradually decreasing together with the decrease of the crossing profile of the devices used in practice. However, when they occur, they often require surgical treatment. The growing experience of the team not only while obtaining the access but also while achieving adequate hemostasis ("patent hemostasis") is of great importance for minimizing the complications.

Safety of catheter-based radiofrequency renal denervation on branch renal arteries in a porcine model

OBJECTIVES

We aimed to investigate the safety of radiofrequency (RF)-renal denervation (RDN) on branch renal arteries (RAs) in a porcine model.

BACKGROUND

The efficacy of RF-RDN was enhanced by treatment of the branch RA, in addition to the main RA. However, there are concerns regarding the safety of RF-RDN on branch RA because of their smaller diameter and proximity to the kidney.

METHODS

RF was delivered to 24 RA from 12 swine. A total of 8 RA from 4 swine were untreated. Treated RA were examined by angiography and histopathology at 7, 30, and 90 days. Serum creatinine concentration, biophysical parameters during RF delivery, and renal norepinephrine concentration were also assessed.

RESULTS

Angiography revealed minimal late lumen loss and diameter stenosis in the main and branch RA at any time point. There was no change in serum creatinine after RF-RDN. Histopathologically, no augmentation of medial damage or neointimal formation was found in branch RA compared with main RA. No or minimal damage to surrounding tissues including the kidneys, ureters, lymph nodes, and muscles was observed at any time point in both the main and branch RA. Equivalent electrode temperature in the main and branch RA was achieved by automatic adjustment of output power by the generator. The renal norepinephrine concentration was significantly lower in the treated group compared with the untreated group.

CONCLUSIONS

RF-RDN on branch RA was safe in a porcine model, with stenosis-free healing of treated arteries and negligible kidney damage at 7, 30, and 90 days.