Eligibility for percutaneous renal denervation: the importance of a systematic screening

Stepwise treatment of uncontrolled HyperTensioN (Stepwise-HTN): Study design of a cluster randomised controlled trial in primary care

BACKGROUND

Uncontrolled hypertension is a major health problem, and a key risk factor for cardiovascular disease. Most patients are detected and managed in primary care, but approximately 50% remains uncontrolled. Our aim is to assess whether a guided stepwise work-up management strategy for patients with uncontrolled hypertension in primary care would result in better blood pressure control in these patients compared to usual care.

METHODS

A cluster randomised controlled trial aiming at randomizing 40 general practices to either "a protocolised stepwise work-up" or to "usual care". Uncontrolled hypertension is defined as an office blood pressure (BP) >140/90 mmHg while being prescribed three or more antihypertensive drugs simultaneously from different therapeutic classes for three or more months in an adequate dose. In the intervention arm, patients with uncontrolled hypertension will receive the stepwise approach, consisting of (i) excluding a white coat effect, (ii) re-evaluation of lifestyle, (iii) re-evaluation of drug adherence, (iv) optimalisation of antihypertensive treatment and (v) referral if the office BP is still >140/90 mmHg. The control group receives usual care in a regular program for cardiovascular risk management. The primary outcome is the absolute difference in the mean 24-h systolic BP between intervention and control arm after 8 months. Secondary outcomes include differences in the percentage of patients achieving a controlled BP, and time to reach a controlled BP.

CONCLUSION

If stepwise treatment of uncontrolled hypertension is proven effective, the strategy could be implemented by blending the approach to the cardiovascular risk management already applied in general practice. Trial registration NTR7304, https://www.trialregister.nl/trial/7099.

High screen failure rate in patients with resistant hypertension: Findings from SYMPLICITY HTN-3

BACKGROUND

The SYMPLICITY HTN-3 trial, which randomized subjects to renal denervation (RDN) or sham control, was designed to evaluate the efficacy and safety of RDN for the treatment of resistant hypertension. Outcomes were previously reported. This retrospective analysis evaluated reasons for screen failure (SF) for randomization in the trial.

METHODS

SYMPLICITY HTN-3 enrolled subjects with office systolic blood pressure (SBP) ≥160 mmHg on stable and maximal doses of ≥3 antihypertensive medication classes. Blood pressure was measured during screening visit (SV) 1 and SV2 a minimum of 2 weeks later to ensure resistant hypertension and to exclude white-coat hypertension. We analyzed baseline characteristics and reasons for SF at each SV and changes in BP between SVs.

RESULTS

Among 1,415 patients screened, 880 (62%) did not meet criteria for randomization. Compared with randomized patients, those in the SF cohort were more likely to be older (58.7 vs. 57.4 years, P=.029), current smokers (14.5% vs. 10.7%, P=.041), and prescribed fewer antihypertensive medications (4.7 vs. 5.1, P<.001). The predominant reason for SF at SV2 was office SBP <160 mmHg despite office SBP ≥160 mmHg at SV1.

CONCLUSION

Screening patients with resistant hypertension on maximal doses of ≥3 antihypertensive drugs led to a high SF rate. Screen failures were most common at SV1 and were due to failing the office SBP entry criteria. Not meeting ambulatory SBP criteria at SV2 was a secondary reason for SF, often due to white-coat hypertension; thus, 24-hour ambulatory monitoring is important to validate resistant hypertension.

Safety of Temporary Discontinuation of Antihypertensive Medication in Patients With Difficult-to-Control Hypertension

Successful control of blood pressure relies on identification of secondary causes and contributing factors of hypertension. As antihypertensive medication can interfere with diagnostic investigations, temporary discontinuation of medication is advised. However, there are concerns about the safety of temporary discontinuation of antihypertensive medication in patients with difficult-to-control hypertension. We assessed the occurrence of adverse cardiovascular and cerebrovascular events potentially attributable to temporary discontinuation of antihypertensive medication between February 2010 and March 2016 (n=604) in our Analysis of Complicated Hypertension screening program. A reference group (n=604) was extracted from the SMART study (Second Manifestations of Arterial Disease) cohort (comprising a similar cohort at our hospital in whom medication was not stopped) and individually matched for blood pressure, age, sex, and history of cardiovascular disease. Discontinuation of medication was well tolerated; 62% reported no complaints, 24% had mild discomfort that could be left untreated, and 14% experienced complaints that required prescription of antihypertensive escape medication. Three major adverse events were observed in the Analysis of Complicated Hypertension group between discontinuation of medication and 30 days after restart of medication (event rate=31.2 events per 1000 patient-year). In the reference cohort, 5 cardiovascular events were observed during a similar follow-up period (event rate=51.2 events per 1000 patient-year). In conclusion, discontinuation of antihypertensive medication for the diagnostic evaluation of hypertension does not increase the acute risk of cardiovascular events when performed in a well-controlled setting in specialized hospitals with appropriate protocols for monitoring safety.

Impact of Medication Adherence on the Effect of Renal Denervation

Randomized trials of catheter-based renal denervation (RDN) as therapy for resistant hypertension showed conflicting results in blood pressure (BP) lowering effect. Adherence to medication is modest in this patient group and may importantly drive these conflicting results. SYMPATHY is a prospective open label multicenter trial in Dutch patients with resistant hypertension. Primary outcome was change in daytime systolic ambulatory BP at 6 months. Patients were randomly assigned to RDN on top of usual care. Adherence to BP lowering drugs was assessed at baseline and follow-up, using blood samples drawn synchronously with BP measurements. Patients and physicians were unaware of the adherence assessment. Primary analyses showed a mean difference between RDN (n=95) and control (n=44) in changes in daytime systolic ambulatory BP after 6 months of 2.0 mm Hg (95% confidence interval, −6.1 to 10.2 mm Hg) in favor of control. In 80% of patients, fewer medications were detected than prescribed and adherence changed during follow-up in 31%. In those with stable adherence during follow-up, mean difference between RDN and control for daytime systolic ambulatory BP was −3.3 mm Hg (−13.7 to 7.2 mm Hg) in favor of RDN. RDN as therapy for resistant hypertension was not superior to usual care. Objective assessment of medication use shows that medication adherence is extremely poor, when patients are unaware of monitoring. Changes over time in adherence are common and affect treatment estimates considerably. Objective measurement of medication adherence during follow-up is strongly recommended in randomized trials.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01850901.

Renal Denervation in a Real Life Setting: A Gradual Decrease in Home Blood Pressure

OBJECTIVES

To investigate the blood pressure dynamics after renal denervation through monthly home blood pressure measurements throughout the first 12 months.

METHODS

A cohort of 70 patients performed highly standardized monthly home blood pressure monitoring during the first year after denervation according to the European Society of Hypertension guidelines. At baseline and 12 months follow-up, office and ambulatory blood pressure as well as routine physical and laboratory assessment was performed.

RESULTS

Home blood pressure decreased with a rate of 0.53 mmHg/month (95% CI 0.20 to 0.86) systolic and 0.26 mmHg/month (95% CI 0.08 to 0.44) diastolic throughout 12 months of follow-up, while the use of antihypertensive medication remained stable (+0.03 daily defined doses/month, 95% CI -0.01 to 0.08). On average, a 12 month reduction of 8.1 mmHg (95% CI 4.2 to 12.0) was achieved in home systolic blood pressure, 9.3 mmHg (95% CI -14.2 to -4.4) as measured by 24-hour ambulatory blood pressure monitoring and 15.9 mmHg (95% CI -23.8 to -7.9) on office measurements.

CONCLUSION

Blood pressure reduction after renal denervation occurs as a gradual decrease that extends to at least one-year follow-up. Home monitoring seems a suitable alternative for ambulatory blood pressure monitoring after renal denervation.

Chronic Kidney Disease As a Potential Indication for Renal Denervation

Renal denervation is being used as a blood pressure lowering therapy for patients with apparent treatment resistant hypertension. However, this population does not represent a distinct disease condition in which benefit is predictable. In fact, the wide range in effectiveness of renal denervation could be a consequence of this heterogeneous pathogenesis of hypertension. Since renal denervation aims at disrupting sympathetic nerves surrounding the renal arteries, it seems obvious to focus on patients with increased afferent and/or efferent renal sympathetic nerve activity. In this review will be argued, from both a pathophysiological and a clinical point of view, that chronic kidney disease is particularly suited to renal denervation.

Renal denervation in hypertensive patients not on blood pressure lowering drugs

Introduction

Studies on the blood pressure lowering effect of renal denervation (RDN) in resistant hypertensive patients have produced conflicting results. Change in medication usage during the studies may be responsible for this inconsistency. To eliminate the effect of medication usage on blood pressure we focused on unmedicated hypertensive patients who underwent RDN.

Methods and results

Our study reports on a cohort of patients, who were not on blood pressure lowering drugs at baseline and during follow-up, from eight tertiary centers. Data of patients were used when they were treated with RDN and had a baseline office systolic blood pressure (SBP) ≥140 mmHg and/or 24-h ambulatory SBP ≥130 mmHg. Our primary outcome was defined as change in office and 24-h SBP at 12 months after RDN, compared to baseline. Fifty-three patients were included. There were three different reasons for not using blood pressure lowering drugs: (1) documented intolerance or allergic reaction (57 %); (2) temporary cessation of medication for study purposes (28 %); and (3) reluctance to take antihypertensive drugs (15 %). Mean change in 24-h SBP was −5.7 mmHg [95 % confidence interval (CI) −11.0 to −0.4; p = 0.04]. Mean change in office SBP was −13.1 mmHg (95 % CI −20.4 to −5.7; p = 0.001). No changes were observed in other variables, such as eGFR, body–mass-index and urinary sodium excretion.

Conclusion

This explorative study in hypertensive patients, who are not on blood pressure lowering drugs, suggests that at least in some patients RDN lowers blood pressure.

Electronic supplementary material

The online version of this article (doi:10.1007/s00392-016-0984-y) contains supplementary material, which is available to authorized users.

Renal BOLD-MRI relates to kidney function and activity of the renin-angiotensin-aldosterone system in hypertensive patients

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system are key factors in the pathophysiology of hypertension. Renal hypoxia is the putative mechanism stimulating both systems. Blood oxygen level-dependent MRI (BOLD-MRI) provides a noninvasive tool to determine renal oxygenation in humans. The aim of the current study was to investigate the relation between blood pressure (BP) and kidney function with renal BOLD-MRI. Moreover, the relation between direct and indirect variables of the RAAS and sympathetic nervous system and renal BOLD-MRI was studied.

METHOD

Seventy-five hypertensive patients (38 men) were included. Antihypertensive medication was temporarily stopped. Patients collected urine during 24 h (sodium, catecholamines), blood samples were taken (creatinine, renin, aldosterone), a captopril challenge test was performed, and ambulatory BP was measured.

RESULTS

Mean age was 58 (±11) years, day-time BP was 167 (±19)/102 (±16) mmHg, and estimated glomerular filtration rate was 75 (±18) ml/min per 1.73 m). In multivariable regression analysis, renal medullary R2*-values inversely related to estimated glomerular filtration rate (P = 0.02). Moreover, the BP-lowering effect of captopril positively related to cortical (P = 0.02) and medullary (P = 0.008) R2*-values, as well as to P90 (P = 0.02).

CONCLUSION

In patients with hypertension, kidney function relates to medullary R2*-values. Activation of the RAAS is also positively related to the renal R2*-values.

The blood pressure-lowering effect of renal denervation is inversely related to kidney function

OBJECTIVES

In renal denervation (RDN), a wide range in the blood pressure (BP)-lowering effect has been reported. On the basis of the current knowledge of pathophysiology, we hypothesized that the BP-lowering effect of RDN would be inversely related to kidney function. Second, we investigated whether direct and indirect variables of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) would be related as well.

METHODS

Sixty-seven patients from a prospective cohort of patients treated with RDN with completed 6 months follow-up were included. Data collected during routine standardized work-up before RDN were used: 24-h urine excretion of creatinine, albumin, sodium and catecholamines, plasma creatinine, renin activity and aldosterone, ambulatory BP-monitoring and a captopril challenge test. When considered well tolerated, antihypertensive drugs were stopped before these investigations.

RESULTS

The BP-lowering was inversely related to estimated glomerular filtration rate (eGFR) in patients who stopped antihypertensive drugs prior to testing (ß: 0.46, P = 0.013). There was a positive relation between SBP at baseline and the BP-lowering effect of RDN (ß:-0.55 mmHg per mmHg, P < 0.001). Parameters related to the rennin-angiotensin system (aldosterone, captopril test) and the sympathetic nervous system (dipping pattern and catecholamines in urine) positively related to the BP-lowering effect of RDN.

CONCLUSION

The present explorative study shows an inverse relation between the BP-lowering effect of RDN and eGFR. Second, we found relations between variables of the RAAS and SNS with the BP-lowering effect of RDN. The data complement current concepts on pathophysiology of sympathetic hyperactivity and hypertension and may give some insight in the wide range of the effect of RDN.

Screening for non-adherence to antihypertensive treatment as a part of the diagnostic pathway to renal denervation

Renal denervation is a potential therapeutic option for resistant hypertension. A thorough clinical assessment to exclude reversible/spurious causes of resistance to antihypertensive therapy is required prior to this procedure. The extent to which non-adherence to antihypertensive treatment contributes to apparent resistance to antihypertensive therapy in patients considered for renal denervation is not known. Patients (n=34) referred for renal denervation entered the evaluation pathway that included screening for adherence to antihypertensive treatment by high-performance liquid chromatography-tandem mass spectrometry-based urine analysis. Biochemical non-adherence to antihypertensive treatment was the most common cause of non-eligibility for renal denervation-23.5% of patients were either partially or completely non-adherent to prescribed antihypertensive treatment. About 5.9% of those referred for renal denervation had admitted non-adherence prior to performing the screening test. Suboptimal pharmacological treatment of hypertension and 'white-coat effect' accounted for apparently resistant hypertension in a further 17.7 and 5.9% of patients, respectively. Taken together, these three causes of pseudo-resistant hypertension accounted for 52.9% of patients referred for renal denervation. Only 14.7% of referred patients were ultimately deemed eligible for renal denervation. Without biochemical screening for therapeutic non-adherence, the eligibility rate for renal denervation would have been 38.2%. Non-adherence to antihypertensive treatment and other forms of therapeutic pseudo-resistance are by far the most common reason of 'resistant hypertension' in patients referred for renal denervation. We suggest that inclusion of biochemical screening for non-adherence to antihypertensive treatment may be helpful in evaluation of patients with 'resistant hypertension' prior to consideration of renal denervation.

Renal denervation

PURPOSE OF REVIEW

Renal denervation (RDN) has, within recent years, been suggested as a novel treatment option for patients with resistant hypertension. This review summarizes the current knowledge on this procedure as well as limitations and questions that remain to be answered.

RECENT FINDINGS

The Symplicity HTN-1 (2009) and HTN-2 (2010) studies re-introduced an old treatment approach for resistant hypertension and showed that catheter-based RDN was feasible and resulted in substantial blood pressure (BP) reductions. However, they also raised questions of durability of BP reduction, correct patient selection, anatomical and physiological effects of RDN as well as possible beneficial effects on other diseases with increased sympathetic activity. The long awaited Symplicity HTN-3 (2014) results illustrated that the RDN group and the sham-group had similar reductions in BP.

SUMMARY

Initial studies demonstrated that RDN in patients with resistant hypertension was both feasible and safe and indicated that RDN may lead to impressive reductions in BP. However, recent controlled studies question the BP lowering effect of RDN treatment. Large-scale registry data still supports the favorable BP reducing effect of RDN. We suggest that, in the near future, RDN should not be performed outside clinical studies. The degree of denervation between individual operators and between different catheters and techniques used should be clarified. The major challenge ahead is to identify which patients could benefit from RDN, to clarify the lack of an immediate procedural success parameter, and to establish further documentation of overall effect of treatment such as long-term cardiovascular morbidity and mortality.

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.

The effect of renal denervation on kidney oxygenation as determined by BOLD MRI in patients with hypertension

OBJECTIVES

Renal denervation (RDN) is a promising therapy for resistant hypertension. RDN is assumed to decrease sympathetic activity. Consequently, RDN can potentially increase renal oxygenation. Blood oxygen level-dependent MRI (BOLD-MRI) provides a non-invasive tool to determine renal oxygenation in humans. The aim of the current study was to investigate the effect of RDN on renal oxygenation as determined by BOLD-MRI.

METHODS

Patients with resistant hypertension or the inability to follow a stable drug regimen due to unacceptable side effects were included. BOLD-MRI was performed before and 12 months after RDN. Twenty-seven patients were imaged on 3 T and 19 on 1.5 T clinical MRI systems.

RESULTS

Fifty-four patients were included, 46 patients (23 men, mean age 57 years) completed the study. Mean 24-h BP changed from 163(±20)/98(±14) mmHg to 154(±22)/92(±13) mmHg (p = 0.001 and p < 0.001). eGFR did not change after RDN [77(±18) vs. 79(±20) mL/min/1.73 m(2); p = 0.13]. RDN did not affect renal oxygenation [1.5 T: cortical R2*: 12.5(±0.9) vs. 12.5(±0.9), p = 0.94; medullary R2*: 19.6(±1.7) vs. 19.3(1.4), p = 0.40; 3 T: cortical R2*: 18.1(±0.8) vs. 17.8(±1.2), p = 0.47; medullary R2*: 27.4(±1.9) vs. 26.7(±1.8), p = 0.19].

CONCLUSION

The current study shows that RDN does not lead to changes in renal oxygenation 1 year after RDN as determined by BOLD-MRI.

KEY POINTS

• Renal denervation significantly decreased ambulatory blood pressure. • Renal denervation did not change renal oxygenation as determined by BOLD-MRI. • Absence of a change in renal oxygenation might be explained by autoregulation.

Cost-effectiveness of renal denervation therapy for the treatment of resistant hypertension in The Netherlands

OBJECTIVES

Safety and efficacy data for catheter-based renal denervation (RDN) in the treatment of resistant hypertension have been used to estimate the cost-effectiveness of this approach. However, there are no Dutch-specific analyses. This study examined the cost-effectiveness of RDN from the perspective of the healthcare payer in The Netherlands.

METHODS

A previously constructed Markov state-transition model was adapted and updated with costs and utilities relevant to the Dutch setting. The cost-effectiveness of RDN was compared with standard of care (SoC) for patients with resistant hypertension. The efficacy of RDN treatment was modeled as a reduction in the risk of cardiovascular events associated with a lower systolic blood pressure (SBP).

RESULTS

Treatment with RDN compared to SoC gave an incremental quality-adjusted life year (QALY) gain of 0.89 at an additional cost of €1315 over a patient's lifetime, resulting in a base case incremental cost-effectiveness ratio (ICER) of €1474. Deterministic and probabilistic sensitivity analyses (PSA) showed that treatment with RDN therapy was cost-effective at conventional willingness-to-pay thresholds (€10,000-80,000/QALY).

CONCLUSION

RDN is a cost-effective intervention for patients with resistant hypertension in The Netherlands.

[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.

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.

Effects of renal denervation on end organ damage in hypertensive patients

BACKGROUND

Renal denervation (RDN) is believed to reduce sympathetic nerve activity and is a potential treatment for resistant hypertension. The present study investigated the effects of RDN on end organ damage (EOD).

DESIGN

The present study was a prospective cohort study (registered as NCT01427049).

METHODS

Uncontrolled hypertensive patients underwent a work-up prior to and one year after RDN. Cardiac magnetic resonance (CMR) imaging was used to determine left ventricular (LV)-mass; pulse wave analysis and pulse wave velocity (PWV) were used for evaluation of central blood pressure (BP) and arterial stiffness and 24-hour urine was collected for assessment of urinary albumin excretion. The 24-hour ambulatory BP measurement (ABPM) was used to evaluate the effect of RDN on BP.

RESULTS

Fifty-four patients gave informed consent for study participation. Mean age was 58 ± 10 years, 50% were male. One year after RDN, mean ABPM decreased by 7 ± 18/5 ± 11 mm Hg (p = 0.01/p < 0.01). In the patients followed-up in a standardised fashion ABPM decreased by 5 ± 18/4 ± 12 mm Hg (n = 34; p = 0.11/p = 0.09). Mean body surface area indexed LV-mass decreased by 3.3 ± 11.5 g/m(2) (corresponding to a 3 ± 11% reduction; p = 0.09). PWV increased by 2.9 (-2.2 to +6.1) m/s (p = 0.04). Augmentation index corrected for 75 beats per min did not change (median increase 3.0 (-7 to +17) mm Hg; p = 0.89). Urinary albumin excretion did not change during follow-up (mean decrease 10 ± 117 mg/24 hour; p = 0.61).

CONCLUSION

In the current study, we observed a modest effect from renal denervation. Moreover, RDN did not result in a statistical significant effect on end organ damage 12 months after treatment.

Renal denervation in multiple renal arteries

BACKGROUND

In most previous studies investigating efficacy of renal denervation (RDN), patients with multiple renal arteries are generally excluded from treatment. This study was designed to determine the prevalence of multiple renal arteries in patients referred for RDN, to propose a classification for anatomical eligibility and to investigate the relation between the presence of multiple arteries and blood pressure (BP)-lowering effect.

MATERIALS AND METHODS

Patients referred for RDN who underwent noninvasive imaging of the renal arteries before treatment were included in present analysis. Eligible patients were treated. Renal function and BP were evaluated 6 months after treatment.

RESULTS

Hundred and twenty-six patients referred for RDN were included in present analysis. Thirty-four per cent had multiple arteries. Sixty-nine patients underwent RDN. Office BP significantly reduced from 195 (± 26)/106 (± 14) mmHg to 165 (± 24)/95 (± 14) mmHg (P < 0·001). BP reduction in patients with multiple arteries which were all treated was comparable to patients with solitary arteries. However, patients with multiple which were not all treated showed a trend towards a less pronounced effect of RDN (β: 11·6, P = 0·11). The proposed classification appeared useful by identifying eligible anatomy. Renal function at 6 months did not differ from baseline in all subgroups.

CONCLUSIONS

Based on our results and the high prevalence of multiple arteries, it seems reasonable not to exclude patients with multiple renal arteries from RDN. Current analysis suggests that BP reduction may be less pronounced in patients with multiple renal arteries of whom not all arteries were treated.

The effect of percutaneous renal denervation on muscle sympathetic nerve activity in hypertensive patients

OBJECTIVE

The rationale of percutaneous renal denervation (RDN) is based on extensive studies suggesting that renal nerves contribute to hypertension and that they comprise a sensible treatment target. Muscle sympathetic nerve activity (MSNA) is considered to be one of the few reliable methods to quantify central sympathetic activity. The aim of this current study is to determine the effect of RDN on MSNA in a standardized fashion.

METHODS

MSNA was determined in 13 patients before and 6months after RDN. Anti-hypertensive medication was stopped before MSNA. If cessation of medication was considered unsafe, a patient was instructed to use the exact same medication on both occasions.

RESULTS

Ten sets of MSNA recordings were of good quality for analysis. Mean age was 57 ± 3 years and mean eGFR was 85 ± 18 mL/min/1.73 m(2). MSNA was determined twice during a medication free interval in 5 patients; 1 patient used the exact same medication twice, and 4 patients used different drugs. Mean BP changed from 206 ± 7 over 116 ± 4 mmHg, to 186 ± 6 over 106 ± 3 mmHg, 6 months after RDN (p=0.06 for systolic BP, p=0.04 for diastolic BP). Mean resting heart rate did not change (p=0.44). MSNA did not change after RDN: 37 ± 4 bursts/min and 43 ± 4 bursts/min (p=0.11) at baseline and after RDN, respectively. In the 6 patients with standardized medication use during the MSNA sessions, results were comparable.

CONCLUSIONS

Treatment with RDN did not result in a change in MSNA. Changes in BP did not correlate with changes in MSNA.

The effect of renal denervation added to standard pharmacologic treatment versus standard pharmacologic treatment alone in patients with resistant hypertension: rationale and design of the SYMPATHY trial

The first studies on renal denervation (RDN) suggest that this treatment is feasible, effective, and safe in the short term. Presently available data are promising, but important uncertainties exist; therefore, SYMPATHY has been initiated. SYMPATHY is a multicenter, randomized, controlled trial in patients randomized to RDN in addition to usual care (intervention group) or to continued usual care (control group). Randomization will take place in a ratio of 2 to 1. At least 300 participants will be included to answer the primary objective. Sample size may be extended to a maximum of 570 to address key secondary objectives. The primary objective is to assess whether RDN added to usual care compared with usual care alone reduces blood pressure (BP) (ambulatory daytime systolic BP) in subjects with an average daytime systolic BP ≥135, despite use of ≥3 BP-lowering agents, 6 months after RDN. Key secondary objectives are evaluated at 6 months and at regular intervals during continued follow-up and include the effect of RDN on the use of BP-lowering agents, in different subgroups (across strata of estimated glomerular filtration rate and of baseline BP), on office BP, quality of life, and cost-effectiveness.

Blood pressure changes after renal denervation at 10 European expert centers

We did a subject-level meta-analysis of the changes (Δ) in blood pressure (BP) observed 3 and 6 months after renal denervation (RDN) at 10 European centers. Recruited patients (n=109; 46.8% women; mean age 58.2 years) had essential hypertension confirmed by ambulatory BP. From baseline to 6 months, treatment score declined slightly from 4.7 to 4.4 drugs per day. Systolic/diastolic BP fell by 17.6/7.1 mm Hg for office BP, and by 5.9/3.5, 6.2/3.4, and 4.4/2.5 mm Hg for 24-h, daytime and nighttime BP (P⩽0.03 for all). In 47 patients with 3- and 6-month ambulatory measurements, systolic BP did not change between these two time points (P⩾0.08). Normalization was a systolic BP of <140 mm Hg on office measurement or <130 mm Hg on 24-h monitoring and improvement was a fall of ⩾10 mm Hg, irrespective of measurement technique. For office BP, at 6 months, normalization, improvement or no decrease occurred in 22.9, 59.6 and 22.9% of patients, respectively; for 24-h BP, these proportions were 14.7, 31.2 and 34.9%, respectively. Higher baseline BP predicted greater BP fall at follow-up; higher baseline serum creatinine was associated with lower probability of improvement of 24-h BP (odds ratio for 20-μmol l⁻¹ increase, 0.60; P=0.05) and higher probability of experiencing no BP decrease (OR, 1.66; P=0.01). In conclusion, BP responses to RDN include regression-to-the-mean and remain to be consolidated in randomized trials based on ambulatory BP monitoring. For now, RDN should remain the last resort in patients in whom all other ways to control BP failed, and it must be cautiously used in patients with renal impairment.

International expert consensus statement: Percutaneous transluminal renal denervation for the treatment of resistant hypertension

Catheter-based radiofrequency ablation technology to disrupt both efferent and afferent renal nerves has recently been introduced to clinical medicine after the demonstration of significant systolic and diastolic blood pressure reductions. Clinical trial data available thus far have been obtained primarily in patients with resistant hypertension, defined as standardized systolic clinic blood pressure ≥ 160 mm Hg (or ≥ 150 mm Hg in patients with type 2 diabetes) despite appropriate pharmacologic treatment with at least 3 antihypertensive drugs, including a diuretic agent. Accordingly, these criteria and blood pressure thresholds should be borne in mind when selecting patients for renal nerve ablation. Secondary forms of hypertension and pseudoresistance, such as nonadherence to medication, intolerance of medication, and white coat hypertension, should have been ruled out, and 24-h ambulatory blood pressure monitoring is mandatory in this context. Because there are theoretical concerns with regard to renal safety, selected patients should have preserved renal function, with an estimated glomerular filtration rate ≥ 45 ml/min/1.73 m(2). Optimal periprocedural management of volume status and medication regimens at specialized and experienced centers equipped with adequate infrastructure to cope with potential procedural complications will minimize potential patient risks. Long-term safety and efficacy data are limited to 3 years of follow-up in small patient cohorts, so efforts to monitor treated patients are crucial to define the long-term performance of the procedure. Although renal nerve ablation could have beneficial effects in other conditions characterized by elevated renal sympathetic nerve activity, its potential use for such indications should currently be limited to formal research studies of its safety and efficacy.