Endovascular radiofrequency renal denervation in treating refractory arterial hypertension: a preliminary experience

The effects of renal denervation on resistant hypertension patients: a meta-analysis

We carried out this meta-analysis to assess the effects of renal denervation (RDN) on resistant hypertension patients. According to the collaborative review group search strategy, we searched MEDLINE (1996 to 2015.10); EBCO (1996 to 2015.10) and CNKI. A meta-analysis was carried out using RevMan 5.0. We identified 11 reports that fulfilled the inclusion criteria for our review. Controlled trials reporting systolic blood pressure (SBP), diastolic blood pressure in RDN, and control groups at the 6-month follow-up in patients with resistant hypertension were systematically reviewed. Pooled analysis of all 11 included studies showed significant reductions in SBP (weighted mean difference -13.9 mmHg, 95% confidence interval -21.17 to -6.63, P=0.00025, I=93%) and diastolic blood pressure (weighted mean difference -4.41 mmHg, 95% confidence interval -6.95 to -1.88, P=0.004, I=90%) compared with the control group at the 6-month follow-up. Six controlled trials reported specific values of ambulatory SBP that showed no significant difference between two groups. It has also been found that RDN has benefits in protecting cardiac and renal function compared with the control group without increasing adverse events. In conclusion, this meta-analysis shows that RDN is superior to the control group in lowering office blood pressure rather than ambulatory SBP, and might have other potential benefits to protect heart and renal function.

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.

Ischemia and reactive oxygen species in sympathetic hyperactivity states: a vicious cycle that can be interrupted by renal denervation?

Renal denervation has developed as a new treatment strategy for patients suffering from resistant hypertension. The success of this therapy is due to the fact that sympathetic hyperactivity is involved in the pathogenesis of elevated blood pressure. However, not only the sympathetic nervous system (SNS), but also the renin angiotensin system (RAS) is known to be involved in hypertension. In addition, RAS is involved in other sympathetic hyperactivity states, such as heart failure, chronic kidney disease, insulin resistance and obstructive sleep apnea. Moreover, renal denervation has a beneficial effect on patients suffering from these disease states. Recent research suggested that the production of reactive oxygen species (ROS) is elevated in sympathetic hyperactivity states, and that ROS are able to activate the SNS and local tissue renin angiotensin system. Therefore, this review discusses the possibility of ROS as a common trigger of SNS and RAS activity in sympathetic hyperactivity states, and the effect of renal denervation on this ROS production.

International RCT-based guidelines for use of preoperative stress testing and perioperative beta-blockers and statins in non-cardiac surgery

BACKGROUND

Cardiologists frequently advise on perioperative care for non-cardiac surgery and require guidance based on randomised controlled trials that are not discredited by misconduct or misreporting. Regional political bodies currently do not provide this. We therefore examined the credible randomised controlled trial (RCT) evidence on key cardiac perioperative questions which currently have 14 recommendations.

METHODS

Three aspects of perioperative measures were considered: perioperative statins, preoperative stress-testing and perioperative beta-blockade. One author searched PubMed for RCTs considering these topics. All authors independently assessed the RCTs and then collaboratively composed guidelines.

RESULTS

Perioperative statin therapy has been examined by three RCTs, DECREASE III and IV, which are discredited and a third containing serious inconsistencies undermining its validity. Preoperative stress testing has been examined by two RCTs: one discredited trial, DECREASE II, and a second which found no benefit. Perioperative beta-blockade has been examined by eleven RCTs, two of which are discredited. The nine remaining trials together suggest that perioperative beta-blockade increases mortality.

CONCLUSIONS

When the non-credible RCTs are omitted, the evidence base on these three subjects is much smaller than previously believed: 14 recommendations can be replaced by 3. Current guideline arrangements collectively paralyse the numerous signatories from making urgent amendments after initial publication, even when important new information comes to light. Clinicians simply have to wait for the routine five-year expiry. We present a concise scientifically based guideline and commit to updating it responsibly.

Size of blood pressure reduction from renal denervation: insights from meta-analysis of antihypertensive drug trials of 4,121 patients with focus on trial design: the CONVERGE report

OBJECTIVE

30 mm Hg drops in office systolic blood pressure are reported in trials of renal denervation, but ambulatory reductions are much smaller. This disparity is assumed to have a physiological basis and also be present with antihypertensive drugs.

DESIGN

We examine this office-ambulatory discrepancy through meta-analysis of drug and denervation trials, categorising by trial design.

PATIENTS (STUDIES)

31 drug trials enrolling 4121 patients and 23 renal denervation trials enrolling 720 patients met the criteria.

RESULTS

In drug trials without randomisation or blinding, pressure reductions are 5.6 mm Hg (95% CI 2.98 to 8.22 mm Hg) larger on office measurements than ambulatory blood pressure monitoring (p<0.0001). By contrast, with randomisation and blinding, office reductions are identical to ambulatory reductions (difference -0.88 mm Hg, 95% CI -3.18 to 1.43, p=0.45). For renal denervation, there are no randomised blinded trial results. In unblinded trials, office pressure drops were 27.6 mm Hg versus pretreatment, and 26.6 mm Hg versus unintervened controls. By contrast, ambulatory pressure drops averaged 15.7 mm Hg across all trials. Among those where the baseline ambulatory pressure was not the deciding factor for enrolment (avoiding regression to the mean), ambulatory drops averaged only 11.9 mm Hg.

CONCLUSIONS

Discrepancies in drug trials between office and ambulatory blood pressure reductions disappear once double-blinded placebo control is implemented. Renal denervation trials may also undergo similar evolution. We predict that as denervation trial designs gradually improve in bias-resistance, office and ambulatory pressure drops will converge. We predict that it is the office drops that will move to match the ambulatory drops, that is, not 30, but nearer 13.

Renal denervation: a new treatment option in resistant arterial hypertension

Hypertension is one of the most prevalent cardiovascular risk factors. Despite this high prevalence and a broad availability of effective pharmaceutical agents, a significant proportion of patients do not reach treatment goals. Partly this can be explained by secondary causes of hypertension or non-compliance of patients. Nevertheless, a subgroup of patients can be diagnosed with 'resistant hypertension'. Activation of the sympathetic nervous system is known to be an important factor in the development and progression of systemic hypertension. In this context, a percutaneous, catheter-based approach has been developed using radiofrequency energy to disrupt renal sympathetic nerves. The first studies have shown this technique to be safe, illustrated by a lack of vascular or renal injury. More importantly, catheter-based renal nerve ablation resulted in a significant reduction in blood pressure on top of traditional medical therapy. Additional to the encouraging effects shown on hypertension, a positive influence of this intervention in other conditions, characterised by sympathetic overactivation, may be expected. Though this technique seems promising, further studies are needed to address long-term safety and efficacy of renal denervation in hypertension and other disease states.

Renal sympathetic denervation for treatment of resistant hypertension: a systematic review

Catheter-based renal sympathetic denervation (RSD) is a novel technique that is being investigated as treatment for resistant hypertension. To systematically evaluate the existing literature on the safety and efficacy of RSD in persons with resistant hypertension, online searches of Medline and the Cochrane Library Database (up to June 2012) were performed. Randomized controlled trials, observational studies, and conference proceedings published in English language were included. Nineteen studies (N=683 persons) were included. Follow-up duration ranged from 1 to 24 months. All studies reported significant reductions in systolic and diastolic pressures. Maximal reduction of blood pressure ranged from 18 mm Hg to 36 mm Hg (systolic) and 9 mm Hg to 15 mm Hg (diastolic). Sustained benefit of blood pressure reduction at 12 months was seen in 5 studies. No worsening of renal function was reported and there were few procedure-related adverse events such as pseudoaneurysm formation, hypotension, and bradycardia. Data from short-term studies suggest that RSD is a safe and effective therapeutic option in carefully selected patients with resistant hypertension. Long-term studies with large patient populations are needed to study whether this benefit is sustained with a demonstrable difference in cardiovascular disease event rates.

Current views on the management of atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) is a common condition in both elderly patients and those with other vascular disease. No published randomized controlled trial has demonstrated an overall benefit of revascularization on any clinical or biochemical end-point, and optimal medical therapy in this condition is not clearly defined. In this review we consider the epidemiology of ARVD and discuss the evidence for current medical treatment. We also address the literature on revascularization, consider settings in which an interventional approach may still be considered, and touch upon on-going areas of research.