Hype or Hope? Renal Denervation Hits the Headlines

December 21, 2012

LONDON — Renal sympathetic denervation for the treatment of resistant hypertension has been the subject of much media coverage this week, with the publication of one-year results from the Symplicity HTN-2 trial in the December 18, 2012 issue of Circulation by Dr Murray Esler (Baker IDI Heart and Diabetes Institute, Melbourne, Australia) and colleagues, showing 10- to 20-mm-Hg drops in blood pressure with the procedure [1].

These results were first reported at the ACC meeting earlier this year, and in fact, 18-month data were presented at the European Society of Cardiology Congress in the summer, although they are not yet published.

Press coverage of the one-year data varied from some overly sensationalist stories in the lay media, describing the technology as "zapping the kidneys with radio waves" and claiming a "cure" or a "miracle" for hypertension [2], to more responsible ones [3,4], which included outside comment noting that it was important not to overhype this procedure. On Twitter and other social media, journalists and bloggers debated whether complex medical stories should be written by generalist reporters [5,6]. Coverage in the medical press was less evident, likely because much of the data have already been discussed at meetings.

AHA Press Release Overoptimistic?

Yet despite some of the content of the lay-press coverage, most stories did point out that this was a treatment for high blood pressure that was resistant to medication. Some, however, went on to suggest that it could also be a therapy for milder hypertension, likely due to a quote in the AHA press release that accompanied the publication of the paper in Circulation [7].

In this, lead investigator Esler says: "Studies will soon determine whether this procedure can cure mild hypertension, producing permanent drug-free normalization of blood pressure. Based on the blood-pressure declines achieved, reduction in heart attack and stroke rates of more than 40% is anticipated."

The AHA press release is perhaps too optimistic in saying that we will soon know if mild hypertension can be cured by renal denervation.

But Esler told heartwire by email that "the AHA press release is perhaps too optimistic in saying that we will soon know if mild hypertension can be cured by renal denervation." While work in this vein is in progress by several groups, "one being my own in Melbourne," there "will be no answer before the end of 2014," he noted.

The AHA's own press release, while summarizing key data from the story, also included the words "radio waves" and "cure."

To their credit, several of the lay reports, notably the WebMD and HealthDay.com stories, also made it clear that renal denervation, while it is in use in Europe and other parts of the world, has not yet been approved for use in the US. Currently the only use of this procedure there is as part of the Symplicity-3 HTN pivotal trial, which Esler says is "still enrolling. I doubt that analyses will be available before the end of 2013, and perhaps a little later than this." He adds that "there will be no preliminary reports in this double-blind randomized trial."

Time will tell whether renal denervation will live up to expectations

The technology is, in fact, generating great excitement within the medical profession and the hypertension community in particular.

The AHA highlighted the procedure this week by naming it one of the top 10 advances in heart disease and stroke of 2012--" 'Disconnecting' the kidneys might be the key to treating high blood pressure"--which may have further fueled the press coverage of the Symplicity HTN-2 results.

The top brass of cardiology is similarly enthusiastic. When asked to name the biggest stories of the year, hypertension expert Dr Michael Weber (State University of New York, Brooklyn) chose renal denervation and told heartwire : "It's a little unexpected how effective it really is." Editor in chief of theheart.org, Dr Eric Topol (Scripps Translational Science Institute, La Jolla, CA), also highlighted the procedure as one of the "hot" topics. "The renal-denervation procedure to treat hypertension is getting legs, and more data came out in 2012 to suggest it will be here to stay, with the potential for expanded application," he commented.

Small Study Suggests Renal Denervation Does Not Cause Kidney Damage

Separately, a study published online December 19, 2012 in the Journal of the American College of Cardiology, by Dr Oliver Dörr (University of Gissen, Germany) and colleagues found no evidence of procedure-related kidney damage at three-month follow-up in a trial of 62 patients undergoing renal denervation [7]. This included some patients with renal impairment, in whom the procedure also appeared to be safe.

The exclusion of kidney damage from renal denervation "is of major clinical importance," they note. "Our results provide additional evidence that renal sympathetic denervation in patients with resistant hypertension is safe and potentially could be used for patients with progressive chronic kidney disease," they conclude.

Esler received research support from Medtronic Ardian for conducting Symplicity HTN-2. Disclosures for the coauthors are listed in the paper.