A novel, proof-of-concept radiofrequency renal denervation strategy to improve procedural efficiency: 12-month results from the SPYRAL DYSTAL pilot study.

BACKGROUND: Catheter-based renal sympathetic denervation (RDN) reduced blood pressure (BP) in multiple randomized sham-controlled trials of patients with uncontrolled hypertension (HTN). We tested proof-of-concept for a more selective treatment strategy, exclusively targeting these areas to improve the efficiency of the procedure. METHODS: The SPYRAL DYSTAL Pilot study was designed to mirror the SPYRAL HTN-OFF MED Pivotal study, enabling comparison with a propensity score adjusted active-control group. Patients were antihypertensive medication-free for one month before undergoing BP assessment. Those with office BP of 150-180/>90 mmHg and with an ambulatory systolic BP of 140-170 mmHg were selected to undergo open label treatment, delivering energy only to the distal main renal arteries and first order branches. Patients from DYSTAL were compared with patients who underwent maximized RF RDN treatment in the prior randomized OFF MED trial at 3 months. After 3 months, patients resumed antihypertensive medications as indicated. Safety and efficacy outcomes were assessed post hoc through 12 months. RESULTS: The SPYRAL DYSTAL Pilot study treated 56 HTN patients. Baseline office systolic BP (OSBP) and 24-h ambulatory systolic BP (ASBP) were similar between DYSTAL and OFF MED patient groups. The number of ablations (32.3 ± 8.0 vs 46.6 ± 15.3, p < 0.001), procedure time (67 ± 21 min vs 99 ± 36 min; p < 0.001), and contrast volume (173 ± 77 cc vs 208 ± 96 cc; p = 0.014) were significantly lower with the simplified treatment strategy. OSBP and ASBP changes compared with baseline were -9.0 and -1.4 mmHg at 3 months, -20.3 and -13.9 mmHg at 6 months, and -20.3 and -16.6 mmHg at 12 months, respectively. During the medication up-titration phase, BP reductions among DYSTAL patients were similar to reductions observed in OFF MED through 12 months, with comparable number of drugs (1.4 and 1.5 medications, respectively (P=NS)). Two adverse events related to guidewire placement were reported. CONCLUSION: In this pilot study, focusing ablation treatment on the distal main and proximal branch renal arteries was performed, resulting in fewer RF lesions, and reduced contrast volume and procedure time. Whether BP reductions are similar between a selective vs. maximized RDN approach requires further prospective study.

Safety and Efficacy of Renal Denervation in Patients Taking Antihypertensive Medications.

BACKGROUND: Renal denervation (RDN) reduces blood pressure (BP) in patients with uncontrolled hypertension in the absence of antihypertensive medications. OBJECTIVES: This trial assessed the safety and efficacy of RDN in the presence of antihypertensive medications. METHODS: SPYRAL HTN-ON MED is a prospective, randomized, sham-controlled, patient- and assessor-blinded trial enrolling patients from 56 clinical centers worldwide. Patients were prescribed 1 to 3 antihypertensive medications. Patients were randomized to radiofrequency RDN or sham control procedure. The primary efficacy endpoint was the baseline-adjusted change in mean 24-hour ambulatory systolic BP at 6 months between groups using a Bayesian trial design and analysis. RESULTS: The treatment difference in the mean 24-hour ambulatory systolic BP from baseline to 6 months between the RDN group (n = 206; -6.5 ± 10.7 mm Hg) and sham control group (n = 131; -4.5 ± 10.3 mm Hg) was -1.9 mm Hg (95% CI: -4.4 to 0.5 mm Hg; P = 0.12). There was no significant difference between groups in the primary efficacy analysis with a posterior probability of superiority of 0.51 (Bayesian treatment difference: -0.03 mm Hg [95% CI: -2.82 to 2.77 mm Hg]). However, there were changes and increases in medication intensity among sham control patients. RDN was associated with a reduction in office systolic BP compared with sham control at 6 months (adjusted treatment difference: -4.9 mm Hg; P = 0.0015). Night-time BP reductions and win ratio analysis also favored RDN. There was 1 adverse safety event among 253 assessed patients. CONCLUSIONS: There was no significant difference between groups in the primary analysis. However, multiple secondary endpoint analyses favored RDN over sham control. (SPYRAL HTN-ON MED Study [Global Clinical Study of Renal Denervation With the Symplicity Spyral Multi-electrode Renal Denervation System in Patients With Uncontrolled Hypertension in the Absence of Antihypertensive Medications]; NCT02439775).

Patient Preferences for Pharmaceutical and Device-Based Treatments for Uncontrolled Hypertension: Discrete Choice Experiment.

BACKGROUND: Discrete choice experiment is a survey method used to understand how individuals make decisions and to quantify the relative importance of features. Using discrete choice experiment methods, we quantified patient benefit-risk preferences for hypertension treatments, including pharmaceutical and interventional treatments, like renal denervation. METHODS: Respondents from the United States with physician-confirmed uncontrolled hypertension selected between treatments involving a procedure or pills, using a structured survey. Treatment features included interventional, noninterventional, or no hypertension treatment; number of daily blood pressure (BP) pills; expected reduction in office systolic BP; duration of effect; and risks of drug side effects, access site pain, or vascular injury. The results of a random-parameters logit model were used to estimate the importance of each treatment attribute. RESULTS: Among 400 patients completing the survey between 2020 and 2021, demographics included: 52% women, mean age 59.2±13.0 years, systolic BP 155.1±12.3 mm Hg, and 1.8±0.9 prescribed antihypertensive medications. Reduction in office systolic BP was the most important treatment attribute. The remaining attributes, in decreasing order, were duration of effect, whether treatment was interventional, number of daily pills, risk of vascular injury, and risk of drug side effects. Risk of access site pain did not influence choice. In general, respondents preferred noninterventional over interventional treatments, yet only a 2.3 mm Hg reduction in office systolic BP was required to offset this preference. Small reductions in office systolic BP would offset risks of vascular injury or drug side effects. At least a 20% risk of vascular injury or drug side effects would be tolerated in exchange for improved BP. CONCLUSIONS: Reduction in systolic BP was identified as the most important driver of patient treatment preference, while treatment-related risks had less influence. The results indicate that respondents would accept interventional treatments in exchange for modest reductions in systolic BP compared with those observed in renal denervation trials.

Long-term outcomes after catheter-based renal artery denervation for resistant hypertension: final follow-up of the randomised SYMPLICITY HTN-3 Trial.

BACKGROUND: The SYMPLICITY HTN-3 (Renal Denervation in Patients With Uncontrolled Hypertension) trial showed the safety but not efficacy of the Symplicity system (Medtronic, Santa Rosa, CA, USA) at 6 months follow-up in patients with treatment-resistant hypertension. This final report presents the 36-month follow-up results. METHODS: SYMPLICITY HTN-3 was a single-blind, multicentre, sham-controlled, randomised clinical trial, done in 88 centres in the USA. Adults aged 18-80 years, with treatment-resistant hypertension on stable, maximally tolerated doses of three or more drugs including a diuretic, who had a seated office systolic blood pressure of 160 mm Hg or more and 24 h ambulatory systolic blood pressure of 135 mm Hg or more were randomly assigned (2:1) to receive renal artery denervation using the single electrode (Flex) catheter or a sham control. The original primary endpoint was the change in office systolic blood pressure from baseline to 6 months for the renal artery denervation group compared with the sham control group. Patients were unmasked after the primary endpoint assessment at 6 months, at which point eligible patients in the sham control group who met the inclusion criteria (office blood pressure ≥160 mm Hg, 24 h ambulatory systolic blood pressure ≥135 mm Hg, and still prescribed three or more antihypertensive medications) could cross over to receive renal artery denervation. Changes in blood pressure up to 36 months were analysed in patients in the original renal artery denervation group and sham control group, including those who underwent renal artery denervation after 6 months (crossover group) and those who did not (non-crossover group). For comparisons between the renal artery denervation and sham control groups, follow-up blood pressure values were imputed for patients in the crossover group using their most recent pre-crossover masked blood pressure value. We report long-term blood pressure changes in renal artery denervation and sham control groups, and investigate blood pressure control in both groups using time in therapeutic blood pressure range analysis. The primary safety endpoint was the incidence of all-cause mortality, end stage renal disease, significant embolic event, renal artery perforation or dissection requiring intervention, vascular complications, hospitalisation for hypertensive crisis unrelated to non-adherence to medications, or new renal artery stenosis of more than 70% within 6 months. The trial is registered with ClinicalTrials.gov, NCT01418261. FINDINGS: From Sep 29, 2011, to May 6, 2013, 1442 patients were screened, of whom 535 (37%; 210 [39%] women and 325 [61%] men; mean age 57·9 years [SD 10·7]) were randomly assigned: 364 (68%) patients received renal artery denervation (mean age 57·9 years [10·4]) and 171 (32%) received the sham control (mean age 56·2 years [11·2]). 36-month follow-up data were available for 219 patients (original renal artery denervation group), 63 patients (crossover group), and 33 patients (non-crossover group). At 36 months, the change in office systolic blood pressure was -26·4 mm Hg (SD 25·9) in the renal artery denervation group and -5·7 mm Hg (24·4) in the sham control group (adjusted treatment difference -22·1 mm Hg [95% CI -27·2 to -17·0]; p≤0·0001). The change in 24 h ambulatory systolic blood pressure at 36 months was -15·6 mm Hg (SD 20·8) in the renal artery denervation group and -0·3 mm Hg (15·1) in the sham control group (adjusted treatment difference -16·5 mm Hg [95% CI -20·5 to -12·5]; p≤0·0001). Without imputation, the renal artery denervation group spent a significantly longer time in therapeutic blood pressure range (ie, better blood pressure control) than patients in the sham control group (18% [SD 25·0] for the renal artery denervation group vs 9% [SD 18·8] for the sham control group; p≤0·0001) despite a similar medication burden, with consistent and significant results with imputation. Rates of adverse events were similar across treatment groups, with no evidence of late-emerging complications from renal artery denervation. The rate of the composite safety endpoint to 48 months, including all-cause death, new-onset end-stage renal disease, significant embolic event resulting in end-organ damage, vascular complication, renal artery re-intervention, and hypertensive emergency was 15% (54 of 352 patients) for the renal artery denervation group, 14% (13 of 96 patients) for the crossover group, and 14% (10 of 69 patients) for the non-crossover group. INTERPRETATION: This final report of the SYMPLICITY HTN-3 trial adds to the totality of evidence supporting the safety of renal artery denervation to 36 months after the procedure. From 12 months to 36 months after the procedure, patients who were originally randomly assigned to receive renal artery denervation had larger reductions in blood pressure and better blood pressure control compared with patients who received sham control. FUNDING: Medtronic.

Twenty-Four-Hour Pulsatile Hemodynamics Predict Brachial Blood Pressure Response to Renal Denervation in the SPYRAL HTN-OFF MED Trial.

BACKGROUND: Renal denervation (RDN) lowers blood pressure (BP), but BP response is variable in individual patients. We investigated whether measures of pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, predict BP drop following RDN. METHODS: From the randomized, sham-controlled SPYRAL HTN-OFF MED Pivotal trial, we performed a post hoc analysis of BP waveforms from 111 RDN patients and 111 sham controls, obtained with a brachial cuff-based sphygmomanometer. Waveforms were acquired during ambulatory BP monitoring at diastolic BP level and processed with validated ARCSolver algorithms to derive hemodynamic parameters (augmentation index; augmentation pressure; backward and forward wave amplitude; estimated aortic pulse wave velocity). We investigated the relationship between averaged 24-hour values at baseline and the change in 24-hour BP at 3 months in RDN patients, corrected for observed trends in the sham group. RESULTS: There was a consistent inverse relationship between baseline augmentation index/augmentation pressure/backward wave amplitude/forward wave amplitude/estimated aortic pulse wave velocity and BP response to RDN: the decrease in 24-hour systolic BP/diastolic BP was 7.8/5.9 (augmentation index), 8.0/6.3 (augmentation pressure), 6.7/5.4 (backward wave amplitude), 5.7/4.7 (forward wave amplitude), and 7.8/5.2 (estimated aortic pulse wave velocity) mm Hg greater for patients below versus above the respective median value (P<0.001 for all comparisons, respectively). Taking augmentation index/augmentation pressure/backward wave amplitude/forward wave amplitude/estimated aortic pulse wave velocity into account, a favorable BP response following RDN, defined as a drop in 24-hour systolic blood pressure of ≥5 mm Hg, could be predicted with an area under the curve of 0.70/0.74/0.70/0.65/0.62 (P<0.001 for all, respectively). CONCLUSIONS: These results suggest that pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, may predict BP response to RDN.

A re-examination of the SPYRAL HTN-OFF MED Pivotal trial with respect to the underlying model assumptions.

BACKGROUND: The SPYRAL HTN-OFF MED Pivotal trial demonstrated that RDN was efficacious compared to a sham control. The underlying model was an extension of the analysis of covariance (ANCOVA) model, adjusted for baseline blood pressure (BP), and allowed borrowing of information from the previously reported feasibility study using a novel Bayesian method. Fundamental to the estimation of a treatment effect for efficacy are a multitude of statistical modelling assumptions, including the role of outliers, linearity of the association between baseline BP and outcome, and parallelism of the treatment effect difference over the baseline BP range. In this report, we examine the validity of these assumptions to verify the robustness of the treatment effect measured. METHODS: We examined the requisite modelling assumptions of the ANCOVA model fitted to the SPYRAL HTN-OFF MED Pivotal trial using Bayesian methods. To address outliers, we fit a robust regression model (with heavy tailed errors) to the data with diffuse weakly informative prior distributions on the parameters. To address linearity, we replaced the linear baseline term by a natural spline term with 4 degrees of freedom. To address parallelism, we refit the ANCOVA model with an interaction term for treatment arm and baseline BP. RESULTS: ANCOVA models were fitted to the trial data (pooled across the feasibility and pivotal cohorts) using Bayesian methodology with diffuse (non-informative) prior distributions. The modelling assumptions inherent to the ANCOVA models were shown to be broadly satisfied. A robust ANCOVA model yielded a posterior treatment effect of -4.1 mmHg (95% credible interval: -6.3 to -1.9) indicating the influence of outlier values was small. There was moderate evidence of an interaction term effect between baseline BP and treatment, but no evidence of gross violation of linearity in baseline BP. CONCLUSION: The posterior treatment effect estimate is shown to be robust to underlying model assumptions, thus further supporting the evidence of RDN to be an efficacious treatment for resistant hypertension.

Correction to: Rationale and design of two randomized sham­controlled of catheter­based renal denervation in subjects with uncontrolled hypertension in the absence (SPYRAL HTN­OFF MED Pivotal) and presence (SPYRAL HTN­ON MED Expansion) of antihypertensive medications: a novel approach using Bayesian design.

The original version of this article unfortunately contained a mistake.

Efficacy of catheter-based renal denervation in the absence of antihypertensive medications (SPYRAL HTN-OFF MED Pivotal): a multicentre, randomised, sham-controlled trial.

BACKGROUND: Catheter-based renal denervation has significantly reduced blood pressure in previous studies. Following a positive pilot trial, the SPYRAL HTN-OFF MED (SPYRAL Pivotal) trial was designed to assess the efficacy of renal denervation in the absence of antihypertensive medications. METHODS: In this international, prospective, single-blinded, sham-controlled trial, done at 44 study sites in Australia, Austria, Canada, Germany, Greece, Ireland, Japan, the UK, and the USA, hypertensive patients with office systolic blood pressure of 150 mm Hg to less than 180 mm Hg were randomly assigned 1:1 to either a renal denervation or sham procedure. The primary efficacy endpoint was baseline-adjusted change in 24-h systolic blood pressure and the secondary efficacy endpoint was baseline-adjusted change in office systolic blood pressure from baseline to 3 months after the procedure. We used a Bayesian design with an informative prior, so the primary analysis combines evidence from the pilot and Pivotal trials. The primary efficacy and safety analyses were done in the intention-to-treat population. This trial is registered at ClinicalTrials.gov, NCT02439749. FINDINGS: From June 25, 2015, to Oct 15, 2019, 331 patients were randomly assigned to either renal denervation (n=166) or a sham procedure (n=165). The primary and secondary efficacy endpoints were met, with posterior probability of superiority more than 0·999 for both. The treatment difference between the two groups for 24-h systolic blood pressure was -3·9 mm Hg (Bayesian 95% credible interval -6·2 to -1·6) and for office systolic blood pressure the difference was -6·5 mm Hg (-9·6 to -3·5). No major device-related or procedural-related safety events occurred up to 3 months. INTERPRETATION: SPYRAL Pivotal showed the superiority of catheter-based renal denervation compared with a sham procedure to safely lower blood pressure in the absence of antihypertensive medications. FUNDING: Medtronic.

Rationale and design of two randomized sham-controlled trials of catheter-based renal denervation in subjects with uncontrolled hypertension in the absence (SPYRAL HTN-OFF MED Pivotal) and presence (SPYRAL HTN-ON MED Expansion) of antihypertensive medications: a novel approach using Bayesian design.

BACKGROUND: The SPYRAL HTN clinical trial program was initiated with two 80-patient pilot studies, SPYRAL HTN-OFF MED and SPYRAL HTN-ON MED, which provided biological proof of principle that renal denervation has a blood pressure-lowering effect versus sham controls for subjects with uncontrolled hypertension in the absence or presence of antihypertensive medications, respectively. TRIAL DESIGN: Two multicenter, prospective, randomized, sham-controlled trials have been designed to evaluate the safety and efficacy of catheter-based renal denervation for the reduction of blood pressure in subjects with hypertension in the absence (SPYRAL HTN-OFF MED Pivotal) or presence (SPYRAL HTN-ON MED Expansion) of antihypertensive medications. The primary efficacy endpoint is baseline-adjusted change from baseline in 24-h ambulatory systolic blood pressure. The primary safety endpoint is incidence of major adverse events at 1 month after randomization (or 6 months in cases of new renal artery stenosis). Both trials utilize a Bayesian design to allow for prespecified interim analyses to take place, and thus, the final sample sizes are dependent on whether enrollment is stopped at the first or second interim analysis. SPYRAL HTN-OFF MED Pivotal will enroll up to 300 subjects and SPYRAL HTN-ON MED Expansion will enroll up to 221 subjects. A novel Bayesian power prior approach will leverage historical information from the pilot studies, with a degree of discounting determined by the level of agreement with data from the prospectively powered studies. CONCLUSIONS: The Bayesian paradigm represents a novel and promising approach in device-based hypertension trials. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02439749 (SPYRAL HTN-OFF MED Pivotal) and NCT02439775 (SPYRAL HTN-ON MED Expansion).

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.

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

BACKGROUND: Previous randomised renal denervation studies did not show consistent efficacy in reducing blood pressure. The objective of our study was to evaluate the effect of renal denervation on blood pressure in the absence of antihypertensive medications. METHODS: SPYRAL HTN-OFF MED was a multicentre, international, single-blind, randomised, sham-controlled, proof-of-concept trial. Patients were enrolled at 21 centres in the USA, Europe, Japan, and Australia. Eligible patients were drug-naive or discontinued their antihypertensive medications. Patients with an office systolic blood pressure (SBP) of 150 mm Hg or greater and less than 180 mm Hg, office diastolic blood pressure (DBP) of 90 mm Hg or greater, and a mean 24-h ambulatory SBP of 140 mm Hg or greater and less than 170 mm Hg at second screening underwent renal angiography and were randomly assigned to renal denervation or sham control. Patients, caregivers, and those assessing blood pressure were blinded to randomisation assignments. The primary endpoint, change in 24-h blood pressure at 3 months, was compared between groups. Drug surveillance was done to ensure patient compliance with absence of antihypertensive medication. The primary analysis was done in the intention-to-treat population. Safety events were assessed at 3 months. This study is registered with ClinicalTrials.gov, number NCT02439749. FINDINGS: Between June 25, 2015, and Jan 30, 2017, 353 patients were screened. 80 patients were randomly assigned to renal denervation (n=38) or sham control (n=42) and followed up for 3 months. Office and 24-h ambulatory blood pressure decreased significantly from baseline to 3 months in the renal denervation group: 24-h SBP -5·5 mm Hg (95% CI -9·1 to -2·0; p=0·0031), 24-h DBP -4·8 mm Hg (-7·0 to -2·6; p<0·0001), office SBP -10·0 mm Hg (-15·1 to -4·9; p=0·0004), and office DBP -5·3 mm Hg (-7·8 to -2·7; p=0·0002). No significant changes were seen in the sham-control group: 24-h SBP -0·5 mm Hg (95% CI -3·9 to 2·9; p=0·7644), 24-h DBP -0·4 mm Hg (-2·2 to 1·4; p=0·6448), office SBP -2·3 mm Hg (-6·1 to 1·6; p=0·2381), and office DBP -0·3 mm Hg (-2·9 to 2·2; p=0·8052). The mean difference between the groups favoured renal denervation for 3-month change in both office and 24-h blood pressure from baseline: 24-h SBP -5·0 mm Hg (95% CI -9·9 to -0·2; p=0·0414), 24-h DBP -4·4 mm Hg (-7·2 to -1·6; p=0·0024), office SBP -7·7 mm Hg (-14·0 to -1·5; p=0·0155), and office DBP -4·9 mm Hg (-8·5 to -1·4; p=0·0077). Baseline-adjusted analyses showed similar findings. There were no major adverse events in either group. INTERPRETATION: Results from SPYRAL HTN-OFF MED provide biological proof of principle for the blood-pressure-lowering efficacy of renal denervation. FUNDING: Medtronic.