Renal Denervation Shows Promise in Patients Refractory to Stenting

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In patients with persistently high blood pressure despite optimal medical therapy and prior renal artery stenting, renal denervation shows a high rate of efficacy with no vascular complications out to 1 year, according to a small pilot study published in the April 2014 issue of the Journal of Endovascular Therapy.

Researchers led by Yvonne Bausback, MD, of Park Hospital Leipzig (Leipzig, Germany), looked at 10 patients (6 women; mean age 70 years) who had an office systolic blood pressure (BP) greater than 160 mm Hg despite receiving 3 or more antihypertensive drugs (median 6.5) and unilateral or bilateral renal artery stenting. Patients were treated with renal denervation using the Symplicity catheter (Medtronic; Minneapolis, MN) between January 2011 and January 2012.

The number of ablations performed in stented renal arteries was lower than in nonstented, and the catheter was kept a distance of 5 mm from the distal edge of renal stents. Overall, there were no procedure-related complications.

Sustained Pressure Reductions

At 3, 6, and 12 months postprocedure, sustained reductions in mean office systolic and diastolic pressures were seen. Ambulatory pressures also were reduced (table 1).

Table 1. Effect of Renal Denervation on BP

^aP < .001 vs baseline.

^bP < .01 vs baseline.

^cP < .05 vs baseline.

Nine of the 10 patients had a reduction in systolic office BP of 10 mm Hg or more and were considered responders to renal denervation therapy.

Patients and admitting physicians were instructed not to change antihypertensive regimens unless symptomatic hyper- or hypotension occurred. At 6 months, 3 patients remained on the same number of drugs and same dosage of medication. In the remaining patients:

• 3 stayed on the same number of drugs but changed medications
• 2 had their medication increased by 1 additional drug
• 1 patient had a reduction of 2 drugs
• 1 had a reduction of 3 drugs

There were no instances of in-stent restenosis or morphologic findings in the renal artery in any patients nor any cases of dissection or aneurysm. Additionally, there were no changes in mean creatinine, cystatin C, or glomerular filtration rate. Four patients experienced a decrease in urine albumin creatinine ratio ranging from 15.8% to 56.7% compared to their individual baseline values. While renal resistive index measures improved in native arteries (from 0.744 to 0.717; P < .04), the changes in stented renal arteries were not significant (from 0.756 to 0.71; P = .18).

Findings Suggest Potential for Combining Therapies

According to the study authors, renal denervation may fill a gap in treatment since options are limited for patients who do not respond to renal artery stenting, often resulting in additional antihypertensive medications.

“Our findings support the approach of revascularizing renal artery occlusive diseases and following with renal sympathetic denervation in patients with resistant hypertension if the blood pressure fails to respond,” they write. “This is even more useful in patients who present with uncontrolled hypertension and prior renal artery revascularization from any cause and go on to develop drug-resistant hypertension.”

Furthermore, Dr. Bausback and colleagues say, it “might even be appropriate in the future to consider combining renal artery stenting with renal denervation for hypertensive patients with high grade renal artery stenosis.”

The findings also show that once renal artery obstruction is apparent, the ability of the kidney to recover may be compromised. “This suggests that even if renal artery stenosis is not yet clinically relevant, sympathetic denervation might serve to counteract the consequences of atherosclerotic kidney damage,” Dr. Bausback and colleagues say.

Finally, they acknowledge concerns that in patients with prior renal artery stents, use of radiofrequency energy via a metal stent could induce restenosis or occlusion as a result of uncontrolled tissue heating.

Don’t ‘Throw Out the Baby with the Bath Water’

The study comes on the heels of the recent presentation at the American College of Cardiology/i2 Scientific Session and publication in the New England Journal of Medicine of the long-awaited 6-month results of the SYMPLICITY HTN-3 trial showing no change in office or ambulatory systolic BP with renal denervation compared with a sham procedure.

In commentary accompanying the current paper, Giuseppe Biondi-Zoccai, MD, of Sapienza University (Latina, Italy), and colleagues recommend proceeding with a “cautious and constructive approach” in further renal denervation research.

“We should thus not throw out the baby with the bath water,” the editorial notes. “The SIMPLICITY HTN-3 trial failure is not the epitaph of the [transcatheter renal sympathetic denervation] concept but must nonetheless move us into rethinking the pathophysiological basis and clinical translation of this procedure.”

The editorial stresses the importance of avoiding “exceedingly liberal use” of renal denervation, noting that it should not be routinely recommended to all patients with resistant hypertension.

Deepak L. Bhatt, MD, MPH, of Brigham and Women’s Hospital (Boston, MA), co-principal investigator for SYMPLICITY HTN-3, told TCTMD in an email that while the study is interesting, much more work needs to be done to define the role of renal artery denervation in treating severe hypertension in general. The subset in the current paper—patients with prior renal artery stenting—will require additional careful study, he added.

“The apparent safety in this subset is encouraging, but renal denervation as a whole first needs validation in rigorous clinical trials which incorporate the key elements of randomization and blinding,” Dr. Bhatt said.

1. Bausback Y, Friedenberger J, Hertting K, et al. Renal denervation for hypertension refractory to renal artery stenting. J Endovasc Ther. 2014;21:181-190.

2. Biondi-Zoccai G, Peruzzi M, Giordano A, et al. Transcatheter renal sympathetic denervation for resistant arterial hypertension: when sham brings shame [commentary]? J Endovasc Ther. 2014;21:197-201.

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