Renal denervation: ultima ratio or standard in treatment-resistant hypertension

Research status and frontiers of renal denervation for hypertension: a bibliometric analysis from 2004 to 2023

BACKGROUND

Renal Denervation (RDN) is a novel non-pharmacological technique to treat hypertension. This technique lowers blood pressure by blocking the sympathetic nerve fibers around the renal artery, then causing a decrease in system sympathetic nerve excitability. This study aimed to visualize and analyze research hotspots and development trends in the field of RDN for hypertension through bibliometric analysis.

METHODS

In total, 1479 studies were retrieved on the Web of Science Core Collection (WoSCC) database from 2004 to 2023. Using CiteSpace (6.2.R4) and VOSviewer (1.6.18), visualization maps were generated by relevant literature in the field of RDN for hypertension to demonstrate the research status and frontiers.

RESULTS

The number of publications was found to be generally increasing. Europe and the United States were the first countries to carry out research on different techniques and related RDN clinical trials. The efficacy and safety of RDN have been repeatedly verified and gained increasing attention. The study involves multiple disciplines, including the cardiovascular system, peripheral vascular disease, and physiological pathology, among others. Research hotspots focus on elucidating the mechanism of RDN in the treatment of hypertension and the advantages of RDN in appliance therapy. Additionally, the research frontiers include improvement of RDN instruments and techniques, as well as exploration of the therapeutic effects of RDN in diseases with increased sympathetic nerve activity.

CONCLUSION

The research hotspots and frontiers reflect the status and development trend of RDN in hypertension. In the future, it is necessary to strengthen international collaboration and cooperation, conduct long-term clinical studies with a large sample size, and continuously improve RDN technology and devices. These measures will provide new options for more patients with hypertension, thereby improving their quality of life.

New Drugs and Interventional Strategies for the Management of Hypertension

Essential hypertension is an important cause of cardiovascular morbidity and mortality worldwide with significant clinical and economic implications. The field of antihypertensive treatment already numbers numerous agents and classes of drugs. However, patients are still developing uncontrolled hypertension. Hence there is a continuous need for novel agents with good tolerability. Advances in this field are focusing both on pharmacotherapy, with the developments in traditional and non-traditional targets, as well as interventional techniques such as renal denervation and baroreflex activation therapy. It is likely that future strategies may involve a tailored approach to the individual patient, with genetic modulation playing a key role.

Insights on safety and efficacy of renal artery denervation for uncontrolled-resistant hypertension in a high risk population with chronic kidney disease: first Italian real-world experience

Aims

To evaluate the safety and efficacy of catheter-based radiofrequency renal sympathetic denervation (RSD) in a daily practice population of patients with uncontrolled resistant hypertension, on top of medical therapy.

Methods

Consecutive unselected patients with uncontrolled resistant hypertension undergoing RSD were enrolled. Office and ambulatory blood pressure (BP) measurements were collected at baseline and 3, 6 and 12 months after RSD. Efficacy was assessed even in patients with an estimated glomerular filtration rate (eGFR) below 45 mL/min/1.73 m². Patients were defined as responders if systolic BP decreased by at least 5 mmHg at ambulatory BP or by 10 mmHg at office BP at their last follow-up visit.

Results

Forty patients with multiple comorbidities underwent RSD from 2012 to 2019. Baseline office and ambulatory BP was 159.0/84.9 ± 26.2/14.9 mmHg and 155.2/86.5 ± 20.9/14.0 mmHg, respectively. At 12-month follow up a significant reduction in office and ambulatory systolic BP, respectively by − 19.7 ± 27.1 mmHg and by − 13.9 ± 23.6 mmHg, was observed. BP reduction at 12-month follow-up among patients with eGFR < 45 mL/min was similar to that obtained in patients with higher eGFR. Twenty-nine patients (74.4%) were responders. Combined hypertension, higher ambulatory systolic BP and lower E/E’ at baseline emerged as predictors of successful RSD at univariate analysis. No major complications were observed and renal function (was stable up to 12 months), even in patients with the lowest eGFR values at baseline.

Conclusion

RSD is safe and feasible in patients with uncontrolled resistant hypertension on top of medical therapy, even in a high-risk CKD population with multiple comorbidities, with a significant reduction in systolic BP and a trend towards a reduction in diastolic BP lasting up to 12 months.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-00966-7.

Sham-Controlled Randomized Trials of Catheter-Based Renal Denervation in Patients With Hypertension

BACKGROUND

There are conflicting data regarding the relative effectiveness of renal sympathetic denervation (RSD) in patients with hypertension.

OBJECTIVES

The purpose of this study was to evaluate the blood pressure (BP) response after RSD in sham-controlled randomized trials.

METHODS

Databases were searched through June 30, 2018. Randomized trials (RCTs) with ≥50 patients comparing catheter-based RSD with a sham control were included. The authors calculated summary treatment estimates as weighted mean differences (WMD) with 95% confidence intervals (CIs) using random-effects meta-analysis.

RESULTS

The analysis included 977 patients from 6 trials. The reduction in 24-h ambulatory systolic blood pressure (ASBP) was significantly greater for patients treated with RSD than sham procedure (WMD -3.65 mm Hg, 95% CI: -5.33 to -1.98; p < 0.001). Compared with sham, RSD was also associated with a significant decrease in daytime ASBP (WMD -4.07 mm Hg, 95% CI: -6.46 to -1.68; p < 0.001), office systolic BP (WMD -5.53 mm Hg, 95% CI: -8.18 to -2.87; p < 0.001), 24-h ambulatory diastolic BP (WMD -1.71 mm Hg, 95% CI: -3.06 to -0.35; p = 0.01), daytime ambulatory diastolic BP (WMD -1.57 mm Hg, 95% CI: -2.73 to -0.42; p = 0.008), and office diastolic BP (WMD -3.37 mm Hg, 95% CI: -4.86 to -1.88; p < 0.001). Compared with first-generation trials, a significantly greater reduction in daytime ASBP was observed with RSD in second-generation trials (6.12 mm Hg vs. 2.14 mm Hg; p interaction = 0.04); however, this interaction was not significant for 24-h ASBP (4.85 mm Hg vs. 2.23 mm Hg; p interaction = 0.13).

CONCLUSIONS

RSD significantly reduced blood pressure compared with sham control. Results of this meta-analysis should inform the design of larger, pivotal trials to evaluate the long-term efficacy and safety of RSD in patients with hypertension.

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.

Novel approaches for treating hypertension

Hypertension, or high blood pressure, is a prevalent yet modifiable risk factor for cardiovascular disease. While there are many effective treatments available to combat hypertension, patients often require at least two to three medications to control blood pressure, although there are patients who are resistant to such therapies. This short review will briefly update on recent clinical advances and potential emerging therapies and is intended for a cross-disciplinary readership.

Renal Artery Vasodilation May Be An Indicator of Successful Sympathetic Nerve Damage During Renal Denervation Procedure

Autonomic nervous system plays a crucial role in maintaining and regulating vessel tension. Renal denervation (RDN) may induce renal artery vasodilation by damaging renal sympathetic fibers. We conducted this animal study to evaluate whether renal artery vasodilation could be a direct indicator of successful RDN. Twenty-eight Chinese Kunming dogs were randomly assigned into three groups and underwent RDN utilizing temperature-controlled catheter (group A, n = 11) or saline-irrigated catheter (group B, n = 11) or sham procedure (group C, n = 6). Renal angiography, blood pressure (BP) and renal artery vasodilation measurements were performed at baseline, 30-minute, 1-month, and 3-month after interventions. Plasma norepinephrine concentrations were tested at baseline and 3-month after intervention. Results showed that, in addition to significant BP reduction, RDN induced significant renal artery vasodilation. Correlation analyses showed that the induced renal artery vasodilation positively correlated with SBP reduction and plasma norepinephrine reduction over 3 months after ablation. Post hoc analyses showed that saline-irrigated catheter was superior to TC catheter in renal artery vasodilation, especially for the acute dilatation of renal artery at 30-minute after RDN. In conclusion, renal artery vasodilation, induced by RDN, may be a possible indicator of successful renal nerve damage and a predictor of blood pressure response to RDN.

Effects of Renal Denervation Documented in the Austrian National Multicentre Renal Denervation Registry

Renal denervation (RDN) is a new procedure for treatment-resistant hypertensive patients. In order to monitor all procedures undergone in Austria, the Austrian Society of Hypertension established the investigator-initiated Austrian Transcatheter Renal Denervation (TREND) Registry. From April 2011 to September 2014, 407 procedures in 14 Austrian centres were recorded. At baseline, office and mean 24-h ambulatory blood pressure (ABP) were 171/94 and 151/89 mmHg, respectively, and patients were taking a median of 4 antihypertensive medications. Mean 24-h ABP changes after 2–6 weeks, 3, 6 and 12 months were -11/-6, -8/-4, -8/-5 and -10/-6 mmHg (p<0.05 at all measurements), respectively. The periprocedural complication rate was 2.5%. Incidence of long-term complications during follow-up (median 1 year) was 0.5%. Office BP and ABP responses showed only a weak correlation (Pearson coefficient 0.303). Based on the data from the TREND registry, ambulatory blood pressure monitoring in addition to office BP should be used for patient selection as well as for monitoring response to RDN. Furthermore, criteria for optimal patient selection are suggested.

Renal Denervation Prevents Immune Cell Activation and Renal Inflammation in Angiotensin II-Induced Hypertension

RATIONALE

Inflammation and adaptive immunity play a crucial role in the development of hypertension. Angiotensin II and probably other hypertensive stimuli activate the central nervous system and promote T-cell activation and end-organ damage in peripheral tissues.

OBJECTIVE

To determine if renal sympathetic nerves mediate renal inflammation and T-cell activation in hypertension.

METHODS AND RESULTS

Bilateral renal denervation using phenol application to the renal arteries reduced renal norepinephrine levels and blunted angiotensin II-induced hypertension. Bilateral renal denervation also reduced inflammation, as reflected by decreased accumulation of total leukocytes, T cells, and both CD4+ and CD8+ T cells in the kidney. This was associated with a marked reduction in renal fibrosis, albuminuria, and nephrinuria. Unilateral renal denervation, which partly attenuated blood pressure, only reduced inflammation in the denervated kidney, suggesting that this effect is pressure independent. Angiotensin II also increased immunogenic isoketal-protein adducts in renal dendritic cells (DCs) and increased surface expression of costimulation markers and production of interleukin (IL)-1α, IL-1β, and IL-6 from splenic DCs. Norepinephrine also dose dependently stimulated isoketal formation in cultured DCs. Adoptive transfer of splenic DCs from angiotensin II-treated mice primed T-cell activation and hypertension in recipient mice. Renal denervation prevented these effects of hypertension on DCs. In contrast to these beneficial effects of ablating all renal nerves, renal afferent disruption with capsaicin had no effect on blood pressure or renal inflammation.

CONCLUSIONS

Renal sympathetic nerves contribute to DC activation, subsequent T-cell infiltration and end-organ damage in the kidney in the development of hypertension.

Optimum and stepped care standardised antihypertensive treatment with or without renal denervation for resistant hypertension (DENERHTN): a multicentre, open-label, randomised controlled trial

BACKGROUND

Conflicting blood pressure-lowering effects of catheter-based renal artery denervation have been reported in patients with resistant hypertension. We compared the ambulatory blood pressure-lowering efficacy and safety of radiofrequency-based renal denervation added to a standardised stepped-care antihypertensive treatment (SSAHT) with the same SSAHT alone in patients with resistant hypertension.

METHODS

The Renal Denervation for Hypertension (DENERHTN) trial was a prospective, open-label randomised controlled trial with blinded endpoint evaluation in patients with resistant hypertension, done in 15 French tertiary care centres specialised in hypertension management. Eligible patients aged 18-75 years received indapamide 1·5 mg, ramipril 10 mg (or irbesartan 300 mg), and amlodipine 10 mg daily for 4 weeks to confirm treatment resistance by ambulatory blood pressure monitoring before randomisation. Patients were then randomly assigned (1:1) to receive either renal denervation plus an SSAHT regimen (renal denervation group) or the same SSAHT alone (control group). The randomisation sequence was generated by computer, and stratified by centres. For SSAHT, after randomisation, spironolactone 25 mg per day, bisoprolol 10 mg per day, prazosin 5 mg per day, and rilmenidine 1 mg per day were sequentially added from months two to five in both groups if home blood pressure was more than or equal to 135/85 mm Hg. The primary endpoint was the mean change in daytime systolic blood pressure from baseline to 6 months as assessed by ambulatory blood pressure monitoring. The primary endpoint was analysed blindly. The safety outcomes were the incidence of acute adverse events of the renal denervation procedure and the change in estimated glomerular filtration rate from baseline to 6 months. This trial is registered with ClinicalTrials.gov, number NCT01570777.

FINDINGS

Between May 22, 2012, and Oct 14, 2013, 1416 patients were screened for eligibility, 106 of those were randomly assigned to treatment (53 patients in each group, intention-to-treat population) and 101 analysed because of patients with missing endpoints (48 in the renal denervation group, 53 in the control group, modified intention-to-treat population). The mean change in daytime ambulatory systolic blood pressure at 6 months was -15·8 mm Hg (95% CI -19·7 to -11·9) in the renal denervation group and -9·9 mm Hg (-13·6 to -6·2) in the group receiving SSAHT alone, a baseline-adjusted difference of -5·9 mm Hg (-11·3 to -0·5; p=0·0329). The number of antihypertensive drugs and drug-adherence at 6 months were similar between the two groups. Three minor renal denervation-related adverse events were noted (lumbar pain in two patients and mild groin haematoma in one patient). A mild and similar decrease in estimated glomerular filtration rate from baseline to 6 months was observed in both groups.

INTERPRETATION

In patients with well defined resistant hypertension, renal denervation plus an SSAHT decreases ambulatory blood pressure more than the same SSAHT alone at 6 months. This additional blood pressure lowering effect may contribute to a reduction in cardiovascular morbidity if maintained in the long term after renal denervation.

FUNDING

French Ministry of Health.

Treatment resistant hypertension--investigation and conservative management

BACKGROUND

The introduction of invasive treatments, some of which are irreversible, for the entity called treatment-resistant hypertension (TRH) creates the need for a comprehensive discussion of the diagnostic evaluation that TRH requires and the available options for its conservative treatment.

METHOD

The pertinent literature is selectively reviewed in the light of the authors' longstanding clinical experience.

RESULTS

Our review of the literature suggests that the high prevalence of TRH in Germany (ca. 20%) can be nearly halved with the aid of more thorough diagnostic evaluation. Such an evaluation should include a review of the patient's antihypertensive drugs (adherence, daily dosing, concomitant medication), investigation for other vascular changes that might affect blood pressure measurement, and exclusion of white-coat hypertension, sleep apnea syndrome, and secondary rather than essential hypertension. As there have been no randomized trials of treatment for TRH, the physician confronted with such cases must devise treatments on the basis of observational data and pathophysiological reasoning (volume status considering renin levels, sympathetic blockade, vasodilatation). Such measures can presumably lower the number of truly treatment-resistant cases still further.

CONCLUSION

To save patients from preventable harm, patients should undergo a thorough diagnostic evaluation and-under close monitoring for side effects-conservative pharmacological and nonpharmacological treatments should be deployed before any invasive treatment is performed.

New Approaches in the Treatment of Hypertension

Hypertension is the most common modifiable risk factor for cardiovascular disease and death, and lowering blood pressure with antihypertensive drugs reduces target organ damage and prevents cardiovascular disease outcomes. Despite a plethora of available treatment options, a substantial portion of the hypertensive population has uncontrolled blood pressure. The unmet need of controlling blood pressure in this population may be addressed, in part, by developing new drugs and devices/procedures to treat hypertension and its comorbidities. In this Compendium Review, we discuss new drugs and interventional treatments that are undergoing preclinical or clinical testing for hypertension treatment. New drug classes, eg, inhibitors of vasopeptidases, aldosterone synthase and soluble epoxide hydrolase, agonists of natriuretic peptide A and vasoactive intestinal peptide receptor 2, and a novel mineralocorticoid receptor antagonist are in phase II/III of development, while inhibitors of aminopeptidase A, dopamine β-hydroxylase, and the intestinal Na + /H + exchanger 3, agonists of components of the angiotensin-converting enzyme 2/angiotensin(1–7)/Mas receptor axis and vaccines directed toward angiotensin II and its type 1 receptor are in phase I or preclinical development. The two main interventional approaches, transcatheter renal denervation and baroreflex activation therapy, are used in clinical practice for severe treatment resistant hypertension in some countries. Renal denervation is also being evaluated for treatment of various comorbidities, eg, chronic heart failure, cardiac arrhythmias and chronic renal failure. Novel interventional approaches in early development include carotid body ablation and arteriovenous fistula placement. Importantly, none of these novel drug or device treatments has been shown to prevent cardiovascular disease outcomes or death in hypertensive patients.

Renal denervation after Symplicity HTN-3: an update

After three years of excessive confidence, overoptimistic expectations and performance of 15 to 20,000 renal denervation procedures in Europe, the failure of a single well-designed US trial—Symplicity HTN-3—to meet its primary efficacy endpoint has cast doubt on renal denervation as a whole. The use of a sound methodology, including randomisation and blinded endpoint assessment was enough to see the typical 25–30 mmHg systolic blood pressure decrease observed after renal denervation melt down to less than 3 mmHg, the rest being likely explained by Hawthorne and placebo effects, attenuation of white coat effect, regression to the mean and other physician and patient-related biases. The modest blood pressure benefit directly assignable to renal denervation should be balanced with unresolved safety issues, such as potentially increased risk of renal artery stenosis after the procedure (more than ten cases reported up to now, most of them in 2014), unclear long-term impact on renal function and lack of morbidity–mortality data. Accordingly, there is no doubt that renal denervation is not ready for clinical use. Still, renal denervation is supported by a strong rationale and is occasionally followed by major blood pressure responses in at-risk patients who may otherwise have remained uncontrolled. Upcoming research programmes should focus on identification of those few patients with truly resistant hypertension who may derive a substantial benefit from the technique, within the context of well-designed randomised trials and independent registries. While electrical stimulation of baroreceptors and other interventional treatments of hypertension are already “knocking at the door”, the premature and uncontrolled dissemination of renal denervation should remain an example of what should not be done, and trigger radical changes in evaluation processes of new devices by national and European health authorities.

Renal sympathetic denervation after Symplicity HTN-3 and therapeutic drug monitoring in severe hypertension

Renal sympathetic denervation (RDN) has been and is still proposed as a new treatment modality in patients with apparently treatment resistant hypertension (TRH), a condition defined as persistent blood pressure elevation despite prescription of at least 3 antihypertensive drugs including a diuretic. However, the large fall in blood pressure after RDN reported in the first randomized study, Symplicity HTN-2 and multiple observational studies has not been confirmed in five subsequent prospective randomized studies and may be largely explained by non-specific effects such as improvement of drug adherence in initially poorly adherent patients (the Hawthorne effect), placebo effect and regression to the mean. The overall blood-pressure lowering effect of RDN seems rather limited and the characteristics of true responders are largely unknown. Accordingly, RDN is not ready for clinical practice. In most patients with apparently TRH, drug monitoring and improvement of drug adherence may prove more effective and cost-beneficial to achieve blood pressure control. In the meantime, research should aim at identifying characteristics of those patients with truly TRH who may respond to RDN.

[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.

Renal Denervation After Symplicity HTN-3 - Back to Basics. Review of the Evidence

Renal sympathetic denervation (RDN) has been proposed as a new treatment modality in patients with apparent treatment resistant hypertension, a condition defined as office blood pressure elevation despite prescription of at least three antihypertensive drugs including a diuretic. However, the impressive fall in blood pressure reported after RDN in Symplicity HTN-2, the first randomised study, and multiple observational studies has not been confirmed in the US sham-controlled trial Symplicity HTN-3 and four subsequent prospective randomised studies, all published or presented in 2014. The blood pressure reduction documented in earlier studies may be largely due to non-specific effects such as improvement of drug adherence in initially poorly adherent patients (Hawthorne effect), placebo effect and regression to the mean. The overall blood pressure lowering effect of RDN seems rather limited and the characteristics of true responders remain largely unknown. Accordingly, RDN is not ready for clinical practice. In most patients with apparent drug-resistant hypertension, drug monitoring and subsequent improvement of drug adherence may prove more effective and cost-beneficial to achieve blood pressure control. In the meantime, research should aim at identifying characteristics of those few patients adherent to drug treatment and with true resistant hypertension who may respond to RDN.

Joint UK societies' 2014 consensus statement on renal denervation for resistant hypertension

Resistant hypertension continues to pose a major challenge to clinicians worldwide and has serious implications for patients who are at increased risk of cardiovascular morbidity and mortality with this diagnosis. Pharmacological therapy for resistant hypertension follows guidelines-based regimens although there is surprisingly scant evidence for beneficial outcomes using additional drug treatment after three antihypertensives have failed to achieve target blood pressure. Recently there has been considerable interest in the use of endoluminal renal denervation as an interventional technique to achieve renal nerve ablation and lower blood pressure. Although initial clinical trials of renal denervation in patients with resistant hypertension demonstrated encouraging office blood pressure reduction, a large randomised control trial (Symplicity HTN-3) with a sham-control limb, failed to meet its primary efficacy end point. The trial however was subject to a number of flaws which must be taken into consideration in interpreting the final results. Moreover a substantial body of evidence from non-randomised smaller trials does suggest that renal denervation may have an important role in the management of hypertension and other disease states characterised by overactivation of the sympathetic nervous system. The Joint UK Societies does not recommend the use of renal denervation for treatment of resistant hypertension in routine clinical practice but remains committed to supporting research activity in this field. A number of research strategies are identified and much that can be improved upon to ensure better design and conduct of future randomised studies.

Blood pressure response to renal nerve stimulation in patients undergoing renal denervation: a feasibility study

During renal sympathetic denervation (RDN), no mapping of renal nerves is performed and there is no clear end point of RDN. We hypothesized high-frequency renal nerve stimulation (RNS) may increase blood pressure (BP), and this increase is significantly blunted after RDN. The aim of this study was to determine the feasibility of RNS in patients undergoing RDN. Eight patients with resistant hypertension undergoing RDN were included. A quadripolar catheter was positioned at four different sites in either renal artery. RNS was performed during 1 min with a pacing frequency of 20 Hz. After all patients successfully underwent RDN, RNS was repeated at the site of maximum BP response before RDN in either renal artery. Mean age was 66 years. During RNS, BP increased significantly from 108/55 to 132/68 mm Hg (P < 0.001). After RDN, systolic BP response at the site of maximum response to RNS was significantly blunted (+43.1 vs +9.3 mm Hg, P = 0.002). In three patients, a systolic BP increase >10 mm Hg was observed after RDN. In conclusion, RNS resulted in an acute temporary BP increase. This response was significantly blunted after RDN. RNS may potentially serve as an end point for RDN.

Blood pressure and neurohormonal responses to renal nerve ablation in treatment-resistant hypertension

OBJECTIVE

Catheter-based renal nerve ablation is a novel therapy for treatment-resistant hypertension. Although the precise mechanism is unknown, a reduction in global sympathetic tone and renal sympathetic tone, potentially resulting in a decrease in renin, may account for the antihypertensive effect.

DESIGN AND METHODS

In 17 patients (mean age 51.2 ± 9.4 years) with treatment-resistant hypertension (antihypertensive drugs 4.7 ± 1.3), office and ambulatory blood pressure (BP) measurements and circulating concentrations of catecholamines, renin, aldosterone and endothelin-1 were measured at baseline and 6 and 12 months after ablation. Office BP was measured for 1 h at 5-min intervals using an automatic device.

RESULTS

Office BP (164.7 ± 27.7/102.3 ± 19.3  mmHg) decreased by 5.7 ± 18.8  mmHg (P = 0.11) systolic and by 2.6 ± 10.7 (P = 0.33) mmHg diastolic after 6 months, whereas after 12 months decreases were 12.7 ± 16.0  mmHg (P = 0.007) and 7.3 ± 11.9  mmHg (P = 0.02). Heart rate, 24-h (151.8 ± 12.6/94.2 ± 10.3  mmHg) and day and night ambulatory BP did not change, after either 6 or 12 months. Of the neurohormones, only plasma noradrenaline (397  pg/ml, interquartile range 268-461  pg/ml) decreased by 128 ± 167  pg/ml (P = 0.008) after 6 months, whereas other neurohormones remained unchanged. Forty-seven percent of patients had at least 10  mmHg decrease in 24-h ambulatory SBP. In these responders, office and ambulatory BP tended to be higher than in nonresponders, but neurohormones or changes after ablation between responders and nonresponders did not differ.

CONCLUSION

Renal nerve ablation in treatment-resistant hypertensive patients had a moderate effect on office BP and is associated with a decrease in plasma noradrenaline but not in renin. The absent decrease in renin may imply that the intensity of efferent renal denervation achieved with the number of ablations applied was insufficient.

Rationale and design of the Investigator-Steered Project on Intravascular Renal Denervation for Management of Drug-Resistant Hypertension (INSPiRED) trial

The SYMPLICITY studies showed that renal denervation (RDN) is feasible as novel treatment for resistant hypertension. However, RDN is a costly and invasive procedure, the long-term efficacy and safety of which has not yet been proven. Therefore, we designed the INSPiRED trial to compare the blood pressure lowering efficacy and safety of RDN vs usual medical therapy. INSPiRED is a randomized controlled trial enrolling 240 treatment-resistant hypertensive patients at 16 expert hypertension centres in Belgium. Eligible patients, aged 20–69 years old, have a 24-h ambulatory blood pressure of 130 mmHg systolic or 80 mmHg diastolic or more, while taking at least three antihypertensive drugs. They are randomized to RDN (EnligHTN^TM, SJM system) plus usual care (intervention group) or usual care alone (control group) in a ratio of 1:1. The primary endpoints for efficacy and safety, measured after 6 months, are the baseline-adjusted between-group differences in 24h systolic blood pressure and in glomerular filtration rate as estimated by the Chronic Kidney Disease Epidemiology Collaboration equation. Follow-up will continue up to 36 months after randomization. INSPiRED is powered to demonstrate a 10-mmHg difference in systolic blood pressure between randomized groups with a two-sided p-value of 0.01 and 90% power. It will generate long-term efficacy and safety data, identify the subset of treatment-resistant hypertensive patients responsive to RDN, provide information on cost-effectiveness, and by doing so INSPiRED will inform guideline committees and health policy makers. Trial registration: ClinicalTrials.gov Identifier: NCT 01505010.

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.

Renal denervation in the treatment of hypertension

Despite advances in nonpharmacologic and pharmacologic therapy, blood pressure control rates in hypertension are low. About 10 % of patients with hypertension fulfill the criteria of therapy resistance, which is defined as noncontrolled blood pressure despite treatment with ≥3 antihypertensive drugs of different classes, including a diuretic, at optimal or maximal tolerated doses. Although the pathogenesis of resistant hypertension is multifactorial, an interaction between renal afferent and efferent sympathetic nerves and the central nervous system plays a key role, leading to increased renal and central sympathetic activity. Catheter-based renal sympathetic denervation (RDN) is a novel therapeutic technique for the treatment of resistant hypertension. Clinical trials of RDN have shown a significant and sustained reduction of blood pressure as well as renal and central sympathetic activity. In clinical practice, appropriate patient selection is crucial to ensure successful and safe treatment. Beyond hypertension, RDN was associated with reduction of heart rate, regression of left ventricular mass, and improvements in glucose metabolism and severity of sleep apnea. Further studies addressing open questions in the treatment of resistant hypertension and evaluating potential new indications such as metabolic syndrome or heart failure (RE-ADAPT-HF) are necessary to prove effectiveness and safety of RDN in these patients. By modulating sympathetic activity, RDN has the potential to provide benefit in a variety of diseases, but these concepts have to be evaluated in well-designed prospective controlled clinical trials.