Medtronic has announced the start of SYMPLICITY HTN-3, the company’s US clinical trial of the Symplicity renal denervation system for treatment-resistant hypertension. The first patient in this landmark study was enrolled at the Prairie Heart Institute at St John’s Hospital in Springfield, USA.
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 randomised, controlled trial designed to evaluate the safety and effectiveness of renal denervation with the Symplicity renal denervation system in patients with treatment-resistant hypertension.
The study will enrol approximately 530 treatment-resistant hypertension patients across 60 US medical centres. All patients and hypertension follow-up assessors will be blinded to the randomisation 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 randomisation.
“Renal denervation has the potential to extend the lives of millions of people who suffer from treatment-resistant hypertension,” said Krishna Rocha-Singh, 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 US site for SYMPLICITY HTN-1, the original feasibility study of the Symplicity renal denervation system for treatment-resistant hypertension. The site’s principal investigators are Richard Katholi, and Nilesh Goswami.
The national principal investigators of SYMPLICITY HTN-3 are George Bakris, professor of medicine and director of the Hypertension Center at the University of Chicago Medical Center and president of the American Society of Hypertension, and Deepak L Bhatt, 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 Symplicity catheter is introduced through a separate catheter placed through the skin into the femoral artery, located in the upper thigh, and is then threaded up into the renal artery leading to each kidney. It is connected to the Symplicity generator, which produces low-power radiofrequency energy.
Once in place within the renal artery, the tip of the Symplicity catheter is placed against the arterial wall in several places where it delivers RF energy to the surrounding sympathetic nerves according to a proprietary, computer-controlled algorithm. The treatment does not involve a permanent implant and is performed under conscious sedation.
The Symplicity renal denervation 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 Symplicity system is not approved by the US 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 has shown that renal denervation with the Symplicity renal denervation system may provide a significant and sustained reduction in blood pressure levels for many patients with treatment-resistant hypertension.
Published in The Lancet, results from SYMPLICITY HTN-2 –– a randomised, controlled trial of 106 patients in Europe and Australia –– showed that patients with treatment-resistant hypertension randomised to renal denervation achieved a mean blood pressure reduction of 32/12 mmHg (millimeters of mercury) at six months, whereas the patients in the control group randomised 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.
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 the availability of modern antihypertensive agents, approximately 50% of patients with hypertension remain uncontrolled and approximately 15–20% of those are treatment resistant.