2011 ACC: Implantable Pacemaker-like Device Can Keep Blood Pressure in Check

Study results show Rheos implantable device is effective at lowering blood pressure in patients with drug-resistant hypertension.

NEW ORLEANS — April 5, 2011 –A novel implantable device for controlling blood pressure is being tested in a phase III Study, and results are encouraging, according to study results presented in a late-breaking news conference at the American College of Cardiology’s (ACC) 60th Annual Scientific Session and ACC.i2 Summit.

John D. Bisognano, MD, PhD, professor of medicine in the cardiology division at the University of Rochester, NY, presented “Baroreflex Activation Therapy Sustainably Lowers Blood Pressure in Patients with Resistant Hypertension: Results from the Rheos Pivotal Trial.” He said the trial is the first step in showing that the system is safe and that its effect “is as good as two or three drugs for people who are already taking five or six drugs and still aren’t controlled for their hypertension, and is a good option for these patients.”

The Rheos system device is implanted just below the collarbone, like a pacemaker, and delivers four to six volts of electricity to the carotid arteries. The pulses mimic a spike in blood pressure that activate a process called baroflex therapy and “tricks the brain” to lower blood pressure.

For the study, the device was implanted in 265 patients with resistant hypertension of less than 160/mmhg who were taking at least three blood pressure drugs, including a diuretic. All patients were randomized to two groups in a 2 to 1 ratio.

The number of medications taken by patients was similar in the two groups but could not be controlled in the study because patients had blood pressures far above their goals; thus, physicians often changed their medication.

Goup A’s devices delivered baroflex therapy for the study’s full 12-month duration. Group B patients served as the control group for the first half of the study and at six months their devices were programmed to begin treatment.

“If the patients had not reached the target systolic blood pressure (SBP) of 140 mm/hg the device was adjusted on an individual bases to assert and further reduce blood pressure,” said Bisognano. Both groups showed significant reductions in SBP. “In group A, SBP decreased to target levels for 41% of patients after six months and 54% after 12 months,” he said. Group B showed a surprisingly larger placebo effect. “Reductions in SBP at 12 months were at least 50% of those seen at six months, demonstrating a sustained response,” he said. Diastolic blood pressure also fell in both groups at blot time periods.

Although the trial did not meet all primary endpoints, the data show that the therapy significantly reduced blood pressure in patients with resistant hypertension. Bisognano noted that “at 12 months, there was an 88% reduction responder rate -- a 35mmHg blood pressure drop and decrease in left ventricular mass. Future trials need to incorporate measures to improve viability in blood pressure.”

Bisognano also said that he expects the device to be available within a few years, and that cost analysis has shown that is it comparable to drug therapies in this difficult to treat population. Even with the plethora of anti- hypertension drugs, 20-30% still remains uncontrolled, he added.

The study was sponsored by CVRx, which developed the Rheos System. Bisognano is a consultant for the company and has received consulting fees and research support.