Shelley Wood

May 18, 2012

May 18, 2012 (Paris, France) — One year after garnering the "innovation award" at EuroPCR 2011, renal denervation — poised to depose transcatheter aortic-valve implantation (TAVI) as the hottest thing in interventional cardiology — had its own color-coded track in the EuroPCR 2012 program, with debates, live cases, program-building tips, and preliminary results from animal and first-in-human studies with devices still in development.

The Symplicity system (Medtronic) is the far-and-away front runner, having demonstrated average office-based BP drops of 32/12 mm Hg at six months in the SYMPLICITY HTN 2 trial, as reported by heartwire , with 84% of patients having had a ≥10-mm-Hg drop in systolic blood pressure from baseline.

Upwards of 20 other companies, according to Dr Ron Waksman (Washington Hospital, DC), are busy developing competing systems, some of which were featured in a EuroPCR session devoted to emerging technologies.

Leading this pack is St Jude's EnligHTN system, which received CE Mark on the opening day of the meeting. Dr Stephen Worthley (Royal Adelaide Hospital, Australia) presented 30-day results in 47 resistant-hypertension patients treated with the multielectrode, RF-ablation–based system. Mean office BP changes at one month in EnligHTN 1 were -28 systolic and -10 diastolic (p < 0.0001 from baseline), with 78% of patients having systolic BP drops of ≥10 mm Hg.

In terms of safety, no serious complications were seen in the renal artery or at the access site in the EnligHTN study; minor procedure-related events included four hematomas, three vasovagal responses to sheath removal, and two postprocedure transient bradycardias.

Other devices featured in the session included a second RF-energy system and two ultrasound systems.

System Overview Data BP drop, mm Hg
Paradise (ReCor Medical) 6-F balloon catheter, circumferential ultrasound energy First-in-human (15 patients) -32/-16 at 3 mo
Vascular renal denervation (Vessix) Bipolar RF balloon catheter REDUCE-HTN pilot (10 patients) -30/-11 at 1 mo
Tivus (Cardiosonic) 6-F transducer-tipped catheter, ultrasound energy Animal data only N/A

 

Interventionalists who spoke with heartwire were unvaryingly excited about the potential of renal denervation, with some caveats.

"You need enthusiasm to develop new things, and in hypertension we haven't seen an innovation in decades," Dr Thomas Lüscher (University Hospital Zürich, Switzerland) told heartwire . "So just the possibility that you would be able to have a persistent treatment effect by a procedure that helps severe hypertension patients and maybe in the future even the option to cure hypertension is very exciting indeed. But I agree it's a dream at this point. I think we need the SYMPLICITY HTN 3 trial, which hopefully will confirm what the other studies have shown."

Now enrolling at as many as 90 US centers, SYMPLICITY HTN 3, Lüscher pointed out, has design characteristics addressing two concerns with the earlier trials, namely a sham procedure for the control group and ambulatory blood-pressure monitoring in all patients.

No clouds? Dream on

During the same emerging-technologies session, Lüscher explored the albeit-scant data supporting a role for renal denervation in other conditions: everything from metabolic syndrome and obstructive sleep apnea to heart failure, atrial fibrillation, and polycystic-ovary syndrome.

But his counterpoint, Dr Jean Renkin (UCL St Luc University Hospital, Brussels, Belgium), was skeptical, pointing to the myriad unanswered questions with the technology.

"Currently, reasonably solid data are available only for patients with hypertension resistant to pharmacotherapy, which cannot necessarily be extrapolated to other forms of hypertension or conditions referred to [by Dr Lüscher]. However, at this point in time, no clouds have appeared in the sky, so let us dream on."

Renkin had one staggering number for the audience to consider: of 5000 patients who have undergone renal denervation, only 250 were actually treated as part of clinical studies. While no device has US approval, five denervation systems already hold CE Mark in Europe and are being used with increasing frequency.

Treating the truly resistant

Another talking point was the proportion of patients who are truly "resistant." The number agreed on by Lüscher, Waksman, and session comoderator Dr Robert Whitbourn (St Vincent's Hospital, Fitzroy, Australia) was that just 3% of all hypertensive patients receiving blood-pressure–lowering medication are truly "resistant." Numbers as high as 30% have been suggested in other reports, he noted.

"Interestingly, when we've been involved in various trials, every cardiologist says they have hundreds of these patients, but when we actually go to get them, no one actually has any," Whitbourn quipped. "I think it should be a sobering thought — the numbers are actually quite small."

Dr William Wijns (Cardiovascular Center Aalst, Belgium), also speaking with heartwire , agreed that the subset was "small" but argued it was "still big numbers, millions of people," and "a massive unmet need."

Waksman, insisting he was "excited" by what he called "robust reductions in blood pressure," nevertheless urged eager interventionalists to work with hypertension experts and resist the urge "to jump on patients before we truly verify that they are resistant to medical treatment."

In the vast majority of people even for whom renal denervation is appropriate, it "won't be a cure," Waksman said. "Most of these patients will have to continue on medical treatment — this is not replacing medical treatment, it is just getting [patients] more in control."

Lüscher disclosed research contracts with Medtronic and consulting for Medtronic, St Jude, and Vessix. Waksman disclosed receiving research contracts from Boston Scientific, Abbott Vascular, Medtronic, and Biotronic and consulting for Biotronic. Worthley disclosed consulting for St Jude, Medtronic, and Biotronik.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....