Long-term Outcomes with Renal Denervation Show Sustained Benefit

DALLAS, TX—Catheter-based renal denervation by radiofrequency (RF) ablation for patients with refractory hypertension continues to show benefit, according to 2-year follow-up data from the Symplicity HTN-2 trial presented November 17, 2013, at the American Heart Association (AHA) Scientific Sessions.

Six-month results, which showed substantial blood pressure decreases in a small, randomized cohort of patients after renal denervation, were presented November 2010 at the AHA Scientific Sessions and simultaneously published in the Lancet. A small cohort originally assigned to the control group and allowed to cross over to treatment at 6 months saw substantial reductions in blood pressure at 1 year similar to those of patients who originally received treatment (Esler MD et al. Circulation. 2012).

Murray D. Esler, MD, of the Baker IDI Heart and Diabetes Institute (Melbourne, Australia), presented follow-up data out to 2 years in the overall Symplicity HTN-2 trial population of 106 patients with refractory hypertension randomized to renal denervation (n = 52) or control (n = 54).

Continued BP Reductions at 2 Years

At 2 years, office systolic BP was similar for patients initially assigned to renal denervation (153 mm Hg) and those who crossed over at 6 months (144 mm Hg). Patients who crossed over saw substantial reductions in blood pressure similar to those of patients who originally received treatment (-35 mm Hg systolic; P < 0.01 vs. baseline; -13 mm Hg diastolic; P < 0.01 vs. baseline). 

Post-procedure heart rate at 24 months was reduced from baseline in the initial renal denervation group (68 vs. 75 BPM; P < 0.03) but not in the crossover group (70 vs. 72 BPM; P = NS).

The rate of procedural groin hematoma, pseudoaneurysm, and renal artery dissection was < 0.3%, but there were no long-term occurrences of atherogenesis, fibrotic stenosis, renal artery aneurysm, and deterioration in renal function. 

Unanswered Questions Remain

Dr. Esler said the sympathetic nervous system has been neglected in hypertension over the past 3 decades and suggested several reasons for this:

• Ace inhibitors and ARBs are “good drugs” and “there was thought to be no incentive to need anything more”
• Clinical trialists have been working with anti-renal drugs and they have not been particularly interested in the renal system itself
• Pharmaceutical companies funded experimental research in the renin-angiotensin system and not in the nervous system
• Cardiac interventionalists, hypertension specialists, and neuroscientists “live in different worlds”
  

Several mysteries remain to be solved pertaining to an “optimal amount” of denervation, the right preselection strategies, and safety predictions, he continued.  In addition, Dr. Esler suggested there might be a class effect given the varying costs of different drugs. Nevertheless, “I think we have what appears to be a powerful way of treating resistant hypertension,” he concluded. “But we wait on the mother of all renal denervation trials, Symplicity HTN-3, which will be presented in March [2014].” 

Seems Like a ‘Durable Treatment’  

Discussant Scott Kinlay, MBBS, PhD, of the VA Boston Healthcare System (West Roxbury, MA), said despite the painful nature of the procedure and even the very slight risk of renal artery dissection, “it seems like this is a durable treatment.”

Renal denervation is exciting because “it offers better blood pressure control for resistant hypertension and thereby extra benefits in preventing end organ damage,” he explained. “It’s potentially going to reduce left ventricular hypertrophy, possibly arrhythmias, and maybe even improve glucose metabolism.”

Importantly, “ambulatory blood pressure reduction is about a third of office based blood pressure reduction, so it’s going to be important to see how that affects the overall evaluation of this treatment,” Dr. Kinlay concluded.

Esler MD. Renal sympathetic denervation for treatment of drug-resistant hypertension: One-year results from the Symplicity HTN-2 randomized, controlled trial. Presented at: American Heart Association Scientific Sessions; November 17, 2013; Dallas, TX.

Disclosures:

• Dr. Esler reports receiving research grant, travel, and consultancy funding from Medtronic.
• Dr. Kinlay reports receiving research funding from Medtronic, Novartis, and The Medicines Company.

Related Stories:

• Symplicity Works: Renal Denervation Reduces Resistant Hypertension
• Renal Denervation Shows Sustained BP Improvements at 1 Year
• Symplicity Itself: Endovascular RF Ablation Lowers Resistant Hypertension