Renal denervation does not reduce ambulatory blood pressure in patients with resistant hypertension, and denervation procedures may miss targets, according to two studies published in the Journal of the American College of Cardiology.

George L. Bakris, M.D., from University of Chicago Medicine, and colleagues examined the efficacy of renal denervation in patients with resistant hypertension. Patients on a stable antihypertensive regimen including maximally tolerated doses of at least three drugs were randomized to renal denervation or sham control (2-to-1 ratio).

The researchers found that the trial did not demonstrate a benefit of renal artery denervation on reduction in ambulatory BP in either the 24-hour or day and night periods compared with sham.

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Abraham R. Tzafriri, Ph.D., from CBSET Inc., in Lexington, Massachusetts, and colleagues correlated the response to endovascular radiofrequency ablation of renal arteries with distributions of nerve and ganglia. Eight renal arteries underwent multielectrode radiofrequency catheter treatment. Nerve and ganglion distributions and sizes were quantified and compared with 16 control arteries.

The researchers found that with distance from the aorta, there was variation in nerve and ganglion distributions. Only one of eight treated arteries exhibited efficacy where ablation involved all four quadrants, reached a depth of 9.1 mm, and affected 50 percent of nerves. Renal norepinephrine levels remained at baseline value in seven of the treated arteries.

“Renal denervation procedures that do not account for asymmetries in renal periarterial nerve and ganglia distribution may miss targets and fall below the critical threshold for effect,” Tzafriri and colleagues write.

Some authors from the Bakris study disclosed ties to pharmaceutical, medical device, and medical technology companies, including Medtronic, which funded the study. Several authors from the Tzafriri study disclosed financial ties to the pharmaceutical and medical device industries.