October 26, 2011 — Medtronic Inc. announced the start of SYMPLICITY HTN-3, the company’s United States clinical trial of the Symplicity Renal Denervation System for treatment-resistant hypertension. The first patient was enrolled at the Prairie Heart Institute at St. John’s Hospital in Springfield, Ill.
Treatment-resistant hypertension is defined as persistently high blood pressure despite three or more antihypertensive medications of different types. It puts approximately 120 million people worldwide at risk of premature death from kidney disease and cardiovascular events such as stroke, heart attack and heart failure.
Renal denervation is a minimally invasive, catheter-based procedure that modulates the output of nerves that line the walls of the arteries leading to the kidneys. The targeted nerves are part of the sympathetic nervous system, which has been found to play a central role in blood pressure regulation.
SYMPLICITY HTN-3 is a randomized, controlled trial designed to evaluate the safety and effectiveness of renal denervation with the Symplicity system in patients with treatment-resistant hypertension.
The study will enroll approximately 530 patients across 60 United States medical centers. All patients and hypertension follow-up assessors will be blinded to the randomization assignments to remove any potential for bias. The primary endpoints of the study are the change in blood pressure from baseline to six months and incidence of major adverse events up to six months following randomization.
“Renal denervation has the potential to extend the lives of millions of people who suffer from treatment-resistant hypertension,” said Krishna Rocha-Singh, M.D., medical director of the Prairie Vascular Institute and the Prairie Education and Research Cooperative. “Based on the results of prior clinical studies and contemporary clinical practice, this interventional technique could be one of the most significant advances in our approach to addressing this insidious disease to be developed in decades.”
The Prairie Heart Institute has significant prior experience with renal denervation from having been the top United States site for SYMPLICITY HTN-1, the original feasibility study of the Symplicity system. The site’s principal investigators (PIs) are Richard Katholi, M.D., and Nilesh Goswami, M.D.
The national PIs are George Bakris, M.D., and Deepak L. Bhatt, M.D., M.P.H. Bakris is professor of medicine and director of the Hypertension Center at the University of Chicago Medical Center and president of the American Society of Hypertension. Bhatt is associate professor of medicine at Harvard Medical School, chief of cardiology for the VA Boston Healthcare System and director of the Integrated Interventional Cardiovascular Program at Brigham and Women’s Hospital and the VA Boston Healthcare System.
The Symplicity Renal Denervation System consists of a proprietary generator and flexible catheter. The catheter is introduced through a separate catheter placed through the skin into the femoral artery, located in the upper thigh; it is then threaded up into the renal artery leading to each kidney. It is connected to the generator, which produces low-power radiofrequency (RF) energy.
Once in place within the renal artery, the catheter tip is placed against the arterial wall in several places where it delivers RF energy to the surrounding sympathetic nerves; it does so according to a proprietary, computer-controlled algorithm. The treatment does not involve a permanent implant and is performed under conscious sedation.
The Symplicity system has been successfully used since 2007 to treat more than 2,000 patients worldwide. It has been commercially available in Europe and Australia since April 2010. The system is not approved by the U.S. Food and Drug Administration (FDA) for commercial distribution in the United States. The FDA granted Medtronic approval for the SYMPLICITY HTN-3 protocol in August.
Clinical research to date shows that renal denervation with the Symplicity system may provide a significant and sustained reduction in blood pressure levels for many patients with treatment-resistant hypertension.
The Lancet published the results of a randomized, controlled trial of 106 patients in Europe and Australia in the Dec. 4, 2010 issue. The study showed patients with treatment-resistant hypertension randomized to renal denervation achieved a mean blood pressure reduction of 32/12 mmHg (millimeters of mercury) at six months; patients in the control group randomized to anti-hypertensive medications alone had blood pressures that did not vary from baseline (1/0 mmHg). The overall occurrence of adverse events did not differ between groups.
Hypertension is the leading attributable cause of death worldwide. It is a significant, costly and escalating global healthcare problem affecting approximately 1.2 billion people; it is also associated with an increased risk of heart attack, stroke, heart failure, kidney disease and death.
Among adults 40–70 years old, each increment of 20 mmHg in systolic blood pressure (the top number) or 10 mmHg in diastolic blood pressure (the bottom number) doubles the risk of cardiovascular disease. Hypertension is estimated to have a direct cost to the global healthcare system of more than $500 billion annually.
Although pharmaceutical therapy plays a primary role in hypertension management, drugs alone are not effective for all patients. As a result, despite lifestyle changes and availability of modern antihypertensive agents, approximately 50 percent of patients remain uncontrolled and approximately 15–20 percent of those are treatment-resistant.
For more information: www.medtronic.com