Renal Denervation Device Treats Resistant Hypertension

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Vasilios Papademetriou, MD
Vasilios Papademetriou, MD

LOS ANGELES—An investigational multi-electrode ablation catheter system is safe and effective for treating patients with resistant hypertension, according to preliminary results released at the American Heart Association Scientific Sessions 2012.

“Importantly, we observed that the device has a rapid and sustained treatment effect as evidenced by office and ambulatory blood pressure measurements throughout the six-month follow-up period,” said Vasilios Papademetriou, MD, Professor of Medicine at Georgetown University and Director of Hypertension and Cardiovascular Research at the Veterans Affairs Medical Center in Washington D.C.

In addition, there were no serious periprocedural events or changes in renal function, Dr. Papademetriou said.

He presented results from the first 46 patients with resistant hypertension to be treated with the EnligHTN device (St. Jude Medical, St. Paul, Minn.).

Until now, single-tip electrode radiofrequency ablation catheters have been used to achieve sympathetic fiber disruption through the renal artery wall; intentional renal fiber disruption has been found to decrease blood pressure (BP). The multi-electrode catheter was designed to create a stable, predictable pattern of lesions circumferentially around the renal artery wall, thereby producing renal fiber disruption without scarring along with less need for contrast and a shorter procedure time.  

Study participants had an office systolic BP of 160 mm Hg or higher and stable use of  three or more antihypertensive medications concurrently at maximally tolerated doses for a minimum of 14 days before enrollment. One of the drugs had to be a diuretic or the patient had to have previously been on a diuretic but had been documented to be diuretic-intolerant. The primary efficacy outcome was the change in office BP at six months. 

Overall, 34 patients, or 76%, had a treatment response, defined as a 10 mm Hg decrease in systolic BP from baseline.

The baseline office BP of 176/96 mm Hg decreased by a mean of 28/10 mm Hg at one month, 27/10 mm Hg at three months, and 28/10 mm Hg at six months.

The mean reductions in the baseline 24-hour ambulatory BP of 150/83 mm Hg were 10/5 mm Hg, 10/5 mm Hg, and 10/6 mm Hg at one, three, and six months, respectively.

Two-thirds of patients had a large enough BP reduction to permit a lower stage of hypertension classification and treatment. About a third of patients were no longer considered hypertensive.

Dr. Papademetriou and his colleagues observed no renal artery dissections, aneursyms, new stenoses, flow-limiting renal artery vasospasms, or major vascular access complications. Serious events related to the device or procedure included worsening or preexisting proteinuria in one patient, symptomatic hypotension in one patient, and worsening of pre-existing renal artery stenosis in one patient.

The study revealed no clinically significant change in renal function as determined by a 50% or greater reduction in estimated glomerular filtration rate, a twofold increase in serum creatinine, or progression to end-stage renal disease. 

Dr. Papademetriou noted that the study excluded patients who had undergone a prior renal artery intervention or had evidence of renal artery disease with a diameter stenosis greater than 30%. Patients with multiple main renal arteries in either kidney or main renal arteries less than 4 mm in diameter or less than 20 mm in length also were ineligible.

“I am confident that the catheter is an improvement over technologies that we have available because there was no target renal artery that we were unable to access,” he told Renal & Urology News. “Also, minimal manipulation is required to complete the procedure so I don't have any issues with the catheter device.” 

He added: “The remaining questions are related to the procedure. We only enrolled a small number of patients so we need to make sure that that the results are reproducible and that we study a larger number of patients in a randomized trial and ideally with a sham comparator.”

Finally, he said that the ideal length of follow-up is “from two to four years” to determine whether reinnervation occurs.

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