ORLANDO — An innovative implantable device therapy that stimulates baroreceptors safely achieved dramatic long-term blood pressure reduction in patients with refractory hypertension in a phase II study.
On the basis of the highly favorable phase II results, a pivotal phase III clinical trial of the Rheos hypertension system is well underway, Dr. Marcos Rothstein said at the annual meeting of the American College of Cardiology.
The Rheos system consists of a pacemaker-like pulse generator that is surgically implanted near the clavicle, baroreceptor activation leads wrapped around each carotid sinus, and an external programmer. Electrical stimulation of the baroreceptors causes vasodilation, natriuresis, diuresis, and reduction in heart rate, with a resultant dose-dependent decrease in blood pressure, explained Dr. Rothstein, professor of medicine at Washington University in St. Louis.
The phase II study involved 38 American and European patients with stage 2 hypertension. Their mean office cuff blood pressure was 183/105 mm Hg despite an average of 5.1 antihypertensive medications.
After 1 year on the Rheos system, their systolic and diastolic blood pressures dropped by 25 and 15 mm Hg, respectively, and after 3 years, by 31/21 mm Hg. Mean heart rate declined from 78 bpm at baseline to 71 bpm at 1 year and 73 at 3 years. Meanwhile, participants' total antihypertensive drug dosage dropped by more than one-quarter.
These changes were associated with significant improvement in cardiac structure and function. Mean left ventricular mass decreased from a mean baseline of 132.8 g/m
Importantly, 24-hour ambulatory monitoring showed that diurnal variation in blood pressure was maintained.
The complication rate associated with the Rheos system was about 20%. Roughly three-quarters of the problems were related to the implantation procedure.
More than 17 million Americans have uncontrolled hypertension despite medical treatment. Dr. Rothstein said the Rheos device is aimed at the estimated 1 million or more patients with severe persistent hypertension resistant to three or more drugs and no significant anatomic contraindications. “They have the highest possible risk for early death, strokes, heart attacks, and kidney disease. These patients need an entirely new approach to their treatment,” he observed.
Discussant Douglas L. Mann said that the phase II data were “fascinating and compelling.”
“I'm particularly impressed with the impact on structural heart disease. Most people would agree that preventing end-organ damage with your therapy is indeed beneficial,” said Dr. Mann, professor and chief of cardiovascular medicine at Washington University in St. Louis.
The study was sponsored by CVRx Inc. Dr. Rothstein disclosed having no financial conflicts of interest.
The system electrically stimulates the carotid sinus baroreceptors. Courtesy CVRx Inc.