In a new consensus statement, the Joint UK Societies (JUKS)—which includes the British Society of Interventional Radiology—say that the evidence for renal denervation is “insufficient” to recommend its routine use in clinical practice. However, they add that they support ongoing clinical trial programmes of renal denervation and “strongly encourage” clinicians to tell their hypertensive patients about ongoing renal denervation studies.
Melvin D Lobo (William Harvey Research Institute, Queen Mary University London, London, UK) and colleagues write in Heart that a previous JUKS consensus statement on renal denervation—published in 2014—“placed a moratorium” on the use of renal denervation in routine UK clinical practice until further “favourable evidence had emerged”. They explain that the 2014 statement was in response to the results of the SYMPLICITY HTN-3 trial, which found that renal denervation with the Symplicity system (Medtronic) did not significantly reduce blood pressure compared with a sham procedure.
According to Lobo et al, recommendations from this 2014 statement and those from the European Clinical Consensus Conferences “led to new and improved clinical trials of renal denervation utilising input from experts in the field to lead on both the design and execution of studies in collaboration with commercial sponsors”. Therefore, now that several of these studies have been published, JUKS have published a new consensus statement to “consider the new evidence that they provide”.
The authors review data both for Medtronic’s radiofrequency Symplicity Spyral system and for ReCor Medical’s ultrasound Paradise system, noting that both system have been associated with significant reductions in ambulatory blood pressure (albeit in different patient populations). “The SPYRAL and RADIANCE [Paradise] study programmes to date have provided encouraging data to suggest that renal denervation may have a role in the treatment of hypertension,” Lobo et al comment. They add that, together, the studies have shown the “value of collaboration” better different disciplines (including industry) and “rekindled enthusiasm for renal denervation in the clinical community”.
However, Lobo et al do outline the limitations of the studies—such as being of short duration—and that the studies have “reported considerable heterogeneity in the response to renal denervation”. Furthermore, they note: “At present, it is unclear which technology may be best for renal denervation, with radiofrequency and ultrasound systems appearing more or less similar in efficacy and ongoing trials of chemical ablation systems are not published yet.”
Thus, Lobo et al report that the JUKS are not changing their position that there is “insufficient evidence to recommend the routine use of renal denervation and that the use of renal denervation should remain restricted to clinical trials”. They do though provide an “agenda” for important areas for future research. These areas include further studies to determine the role of renal denervation in the treatment of hypertension, establishing the safety/durability of different renal denervation technologies, and identifying which patients will be the best responders.
Although they do not advocate the use of renal denervation in routine clinical practice, Lobo et alsay that the JUKS support ongoing clinical trials programmes from the different device manufacturers across the spectrum of renal denervation technologies. They add that they “strongly encourage clinicians who look after patients with hypertension to inform their patients about these studies which are recruiting participants who are on and off medications in order to inform future practice.”
Lobo told BIBA Briefings that he thinks there will be a definitive answer about the role of renal denervation for managing hypertension in “the next two to three years”.
Expanding the role of renal denervation
The need for further studies to better understand the role of renal denervation to manage hypertension has not, however, prevented studies exploring the use of the procedure to treat other cardiac conditions. Lobo said: “I think these studies make a lot of sense particularly where those conditions are characterised by high sympathetic drive. The design of these studies, however, will need to be very carefully thought out given how complex it has been to evaluate the efficacy of renal denervation for hypertension.”
Speaking at EuroPCR 2019 (21–24 May, Paris, France), Marshall Heradien (Department of Internal Medicine, Stellenbosch University, Tygerberg, South Africa) presented a study that evaluated the use of renal denervation for the management of atrial fibrillation. He said that several previous studies “support the idea that renal denervation may have an antiarrhythmic effect”, adding that he and his fellow investigators sought to test the hypothesis that “upstream renal denervation treatment can reduce atrial fibrillation in patients with hypertensive heart disease”.
In the study, 42 patients were randomised to receive treatment with renal denervation (10 with the first-generation Flex catheter and 32 with the second-generation Spyral catheter) and 38 underwent “sham” renal denervation. The primary endpoint was the first event of subclinical atrial fibrillation atrial fibrillation at least six minutes on an implantable loop recorder (which was scanned at six-month intervals).
After an average of three years of follow-up, 19% of the renal denervation group had an episode of atrial fibrillation compared with 47% of the sham procedure group (0.011). Furthermore, patients in the sham procedure experienced significantly more episodes of fast atrial fibrillation: 12% vs. 2% (p=0.002). Renal denervation was also associated with a significant reduction in cardiovascular death at two years: one patient vs. six patients for the sham procedure (p=0.04). However, there were no significant differences in office systolic blood pressure at six months between groups.
Heradien concluded: “In this single-centre randomised controlled trial of patients with hypertensive heart disease, upstream treatment of renal denervation reduced subclinical and fast atrial fibrillation and cardiovascular death.”
Renal denervation has also been explored for the management of heart failure secondary to Chagas’ disease. In Catheterization and Cardiovascular Interventions, André G Spadaro (Heart Institute, University of São Paulo Medical School, São Paulo, Brazil) and others report that renal denervation was “safe and feasible” for patients with Chagas cardiomyopathy. They add that after nine months of follow-up, the primary endpoint (all-cause mortality, myocardial infarction, stroke, need for renal artery invasive treatment or worsening renal function) occurred in 36.4% of 11 patients randomised to undergo renal denervation compared with 50% of six patients randomised to conservative treatment (p=0.06). Spadaro et al state that these findings warrant “future studies to better evaluate the clinical efficacy of the interventional strategy in improving the prognosis of this high-risk population.”
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