ACC 2009: Rheos Hypertension System Demonstrates Feasibility; Phase 3 Trial Under Way

Lisa Nainggolan

March 30, 2009

March 30, 2009 (Orlando, Florida) — Results of a small feasibility study with the Rheos hypertension system (CVRx, Minneapolis, MN), a new implantable device that activates the baroreceptors of the carotid sinus, show that it produces significant reductions in blood pressure in patients with refractory hypertension.

Dr Marcos Rothstein (Washington University School of Medicine, St Louis, MO) presented the findings of the phase 2 study at a late-breaking clinical-trials session here today. The device, on average, dropped blood pressure by 20 mm Hg, which Rothstein said "is nothing short of revolutionary in the treatment of hypertension." Nevertheless, he acknowledged that pivotal data are needed, and a phase 3 study with the Rheos hypertension system is under way in the US. This has enrolled half of its planned 300 patients to date and will follow participants long-term for at least two years, he said.

A panelist at the presentation, Dr Douglas L Mann (Washington University), said: "This really is an innovative trial for a vexing problem. It's fascinating and compelling data." Mann had questions, however, about the age of participants in the phase 2 study--the average age was quite young, at 53 years--and he wondered whether older people, who most typically suffer from hypertension refractory to multiple drug treatment, would be able to tolerate the device. Rothstein said that patients in their late 60s and 70s are being enrolled into the pivotal trial without any problems: "The technical challenges relate more to the neck anatomy and size rather than age."

An Entirely New Approach for Persistent Hypertension

The novel device, which is not unlike a pacemaker, consists of an pulse generator, implanted near the collarbone, and carotid sinus leads. It works by electrically stimulating the carotid sinus, activating pressure reflexes that lower heart rate, dilate blood vessels, and cause natriuresis and diuresis, Rothstein explained. While not the cause of hypertension, pressure receptors within the carotid sinus of hypertensive patients often do not detect intravascular blood pressure and, as a result, the autonomic response is inadequate, he said.

In the study, 61 patients with stage 2 hypertension (160 mm Hg systolic or greater) who were resistant to three or more antihypertensives including a diuretic were enrolled in Europe and the US. The Rheos device was surgically implanted and then activated one month later, and efficacy at three months, one year, and two years after activation was determined. In this study, 38 patients completed two years of chronic device therapy, and 22 completed three years. Patients had the ability to personalize and control therapy by altering the voltage of the device, Rothstein noted.

On average, systolic blood pressure dropped by 25 mm Hg after one year, 22 mm Hg after two years, and 31 mm Hg after three years. The equivalent figures for diastolic blood pressure were 15 mm Hg, 15 mm Hg, and 21 mm Hg, and heart rate also fell. And a significant improvement in left ventricular mass was observed (-25g/m2; p<0.001). No serious adverse events occurred.

Rothstein said there has been a rate of around 20% adverse events with the device, most of which relate to the surgical implantation. However, the rate of infection seen has "been lower than the average for pacemaker implantation," he noted.

Summing up, he said that patients with severe, persistent hypertension that is not amenable to usual medical therapy have the highest possible risk for early death, strokes, and renal disease. These patients "need an entirely new approach to treat their hypertension," he concluded.


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