Results from the Symplicity HTN-2, the first randomised clinical trial investigating renal denervation, were published online before print in Circulation, the Journal of the American Heart Association. These data showed patients, who initially received treatment with the Symplicity renal denervation system (n=47), sustained a significant drop in blood pressure (-28/-10 mm Hg [p<0.001]) compared to baseline at 12 months. The 12 month results demonstrated preservation of the benefit at six month follow-up (-32/-12 mm Hg). No device related serious adverse events, no late vascular complications, and no significant decline in kidney function were reported at 12 months.
The Symplicity renal denervation system is not approved by the US Food and Drug Administration (FDA) for commercial distribution in the United States. Also reported in the manuscript were six month results of 35 patients in the control group who received renal denervation after the primary endpoint was assessed at six months post randomisation (referred to as the crossover group). The crossover group also showed a significant drop in blood pressure six months after the renal denervation procedure (-24/-8 mm Hg [p<0.001]). This decrease in blood pressure is similar to the blood pressure reduction in the initial treatment arm at six months.
“We continue to see positive results from the Symplicity HTN-2 clinical trial, demonstrating consistent, long-term blood pressure reduction with the Symplicity system in patients with treatment-resistant hypertension, who have a three-fold increase in risk of cardiovascular events,” said Murray Esler, principal investigator of the Symplicity HTN-2 trial and senior director of the Baker IDI Heart and Diabetes Institute of Melbourne, Australia. “These data further substantiate the clinical benefits of renal denervation with Symplicity over longer periods of time in this difficult-to-treat patient group.”
Symplicity HTN-2 trial
The Symplicity HTN-2 trial is an international, multi-centre, prospective, randomised, controlled study of renal denervation in patients with treatment-resistant hypertension. One hundred and six patients were randomly allocated in a one-to-one ratio to undergo renal denervation with previous anti-hypertensive medication treatment or to maintain previous anti-hypertensive medication treatment alone (control group) at 24 participating centers. Patients in the control arm of the study were offered renal denervation following assessment of the trial’s primary endpoint at six months following randomisation.
Symplicity renal denervation system
The Symplicity system’s catheter and proprietary generator and algorithms were specifically developed for the renal denervation procedure. The Symplicityrenal denervation system was launched commercially in April 2010 and is currently available in parts of Europe, Asia, Africa, Australia and the Americas and has been used to treat patients with treatment resistant hypertension worldwide.
The Symplicity renal denervation system consists of a flexible catheter and proprietary generator. In an endovascular procedure, similar to an angioplasty, the physician inserts the small, flexible Symplicitycatheter into the femoral artery in the upper thigh and threads it into both renal arteries in turn. Once the catheter tip is in place within the renal artery, the Symplicitygenerator is activated to deliver a controlled, low-power radio-frequency energy routine according to a proprietary algorithm, or pattern, aiming to deactivate the surrounding renal nerves. This, in turn, reduces hyper-activation of the sympathetic nervous system, which is an established contributor to chronic hypertension. The procedure does not involve a permanent implant.
The FDA has granted Medtronic approval for the protocol for SYMPLICITY HTN-3, the company’s US clinical trial of the Symplicity renal denervation system for treatment.