Baroreflex Activation Device Gets Mixed Results : Only three of the five efficacy and safety goals were met in a pivotal study of 265 patients.


Major Finding: Continuous low-voltage stimulation of the carotid sinus by an implanted device led to blood pressure reductions in patients with drug-resistant hypertension. The trial results fulfilled three of five prespecified efficacy and safety goals.

Data Source: The Rheos Pivotal Trial, which enrolled 265 patients with drug-resistant hypertension who received an implanted baroreflex activation device at 37 U.S. centers and 2 centers in Europe.

Disclosures: Dr. Bisognano said that he has received consulting fees or honoraria from CVrx, the company that is developing the carotid baroreflex activation device. Dr. Ram has served on the speakers bureau for the Peer Group and for Advanced Health Media.

NEW ORLEANS – A novel way to manage drug-resistant hypertension using an implanted device to deliver a small, continuous electrical current to both carotid sinuses will need more testing as results from a 265-patient pivotal trial failed to clearly prove efficacy.

The trial results “justify further development” of baroreflex activation therapy, Dr. John D. Bisognano said at the meeting.

“This treatment is coming. The data were very encouraging. This is a modality that will work. I anticipate further studies to better define which patients get the greatest benefit,” said Dr. Bisognano, director of cardiac rehabilitation and clinical preventive cardiology at the University of Rochester (N.Y.).

Cardiologists who heard the results had a mixed read on the potential role of this approach, which involved implanting a small device below the patient's clavicle and placing a pair of electrical leads that wrap around the carotid sinus on each side of the patient's neck.

The device delivers a continuous electrical current of 1-6 V to each carotid sinus, activating the reflex and producing a reduction in blood pressure in most patients.

“When the device becomes available, the greatest benefit will be in patients with end-stage renal failure.

“No matter what you do, their blood pressure does not go down,” commented Dr. C. Venkata S. Ram, professor of medicine at the University of Texas Southwestern Medical Center in Dallas. “I just hope that patients tolerate” having leads in their necks, he added in an interview.

In the study results reported by Dr. Bisognano, 25% of the patients who received the device had at least one procedure-related adverse event within 30 days of device placement, including 4% with permanent nerve injury that resulted in numbness, dysphagia, or dysphonia; 5% with a transient nerve injury; 4% with surgical complication (most of which resolved); and 3% with respiratory complaints (all of which resolved). Overall, 76% of the adverse events resolved, but about 2% of patients required explant of the device.

Dr. Prakesh C. Deedwania took a more skeptical view of the approach. “This device would require battery changes and is subject to malfunctions. In my opinion, renal artery denervation is probably better, right now, for patients with treatment-resistant hypertension,” he said.

The current study's design also “left many unanswered questions,” said Dr. Deedwania, professor of medicine at the University of California, San Francisco, in Fresno. (See View on the News at bottom right.)

The pivotal study for the Rheos baroreflex activation device enrolled patients at 37 U.S. sites and 2 centers in Europe. All 265 patients who were enrolled received placement of the device.

One month after surgery, a 2:1 randomization scheme led to blinded activation of the device in 181 patients and no activation in the other 84. Six months later, the researchers activated all the devices.

The patients averaged 54 years old, about 60% were men, and about three-quarters were white.

Participants had failed to have their blood pressure controlled by an average of five drugs, and they had been on a stable regimen for at least a month at the time of entry.

During the course of the study their treating physicians could freely change antihypertensive drug dosages and also add or remove drugs.

Their systolic and diastolic blood pressure at baseline averaged about 177/103 mm Hg, and their heart rate averaged 74 beats/min.

To qualify for the study, patients needed a minimum blood pressure of at least 160/80 mm Hg and a 24-hour average ambulatory pressure of at least 135 mm Hg, and they had to be on at least three antihypertensive medications.

The study included five primary end points, with a prespecified definition of success for each of the end points.

One end point assessed short-term response after 6 months, defining success as at least a 10–mm Hg drop in systolic pressure compared with baseline. This criterion for success occurred in 54% of patients with an activated device in the study's first 6 months and in 46% of those with an inactive device, an 8% difference in response rate between the active and control arms that failed to meet the prespecified goal of a 20% difference.


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