News Release

Deactivating nerves in the kidneys reduces high blood pressure in patients not responding to drug treatment (Symplicity HTN-2 trial)

Peer-Reviewed Publication

The Lancet_DELETED

Deactivating nerves in the kidney using a burst of radiofrequency energy delivered through a catheter causes large reductions in blood pressure in patients with hypertension who are not responding to drug treatment. Such treatment is these patients is likely to substantially reduce mortality and hypertension-related illness. The findings of the Symplicity HTN-2 trial are published in an Article Online First and in an upcoming Lancet. The study is by Professor Murray D Esler, Baker IDI Heart and Diabetes Institute, Melbourne, Australia, and colleagues. Professor Esler will be presenting the findings at the American Heart Association meeting in Chicago.

Successful treatment of raised blood pressure has proven elusive despite availability of various drugs, combination pharmaceutical products, and resources to assist patients' adherence and lifestyle changes. In about half of hypertensive patients blood pressure remains higher than accepted treatment targets despite broad availability of effective drug treatments.

It is already known that renal (kidney) nerves play a key part in the regulation of blood pressure, through its effects on renin release and sodium reabsorption, and kidney blood flow. Recently developed endovascular catheter technology enables selective denervation of the human kidney, with radiofrequency energy delivered in the renal artery, targeting the relevant renal nerves . In this study, the first randomised controlled trial of this technology, the authors aimed to show that catheter-based renal denervation could safely reduce blood pressure in patients with treatment-resistant hypertension.

Patients with a baseline systolic blood pressure of 160 mm Hg or more (≥150 mm Hg for patients with type 2 diabetes), despite taking three or more antihypertensive drugs, were randomly allocated to undergo renal denervation with previous treatment or to maintain previous treatment alone (control group) at 24 participating centres. The primary effectiveness endpoint was change in seated office-based measurement of systolic blood pressure at 6 months. Primary analysis included all patients remaining in follow-up at 6 months.

106 (56%) of 190 patients screened for eligibility were randomly allocated to renal denervation (n=52) or control (n=54) groups between June 2009, and Jan 2010. 49 (94%) of 52 patients who underwent renal denervation and 51 (94%) of 54 controls were assessed for the primary endpoint at 6 months. Office-based blood pressure measurements in the renal denervation group reduced by 32/12 mm Hg (from a baseline of 178/96 mm Hg), whereas they did not differ from baseline in the control group (change of 1/0 mm Hg, baseline of 178/97 mm Hg). At 6 months, 41 (84%) of 49 patients who underwent renal denervation had a reduction in systolic blood pressure of 10 mm Hg or more*, compared with 18 (35%) of 51 controls. There were no serious procedure-related or device-related complications (such as blood clots in the renal arteries) and occurrence of adverse events did not differ between groups; one patient who had renal denervation had possible progression of an underlying atherosclerotic lesion, but required no treatment.

The authors conclude: "The magnitude of blood-pressure reduction can be predicted to affect the development of hypertension-related diseases and mortality. The technique was applied without major complications. This therapeutic innovation, based on the described neural pathophysiology of essential hypertension, affirms the crucial relevance of renal nerves in the maintenance of raised blood pressure in patients with hypertension. Catheter-based renal denervation is very beneficial for patients with treatment-resistant essential hypertension."

In a linked Comment, Professor Michael Doumas, Veteran Affairs Medical Centre, George Washington University, Washington, DC, USA, and Dr Stella Douma, Aristotle University of Thessaloniki, Thessaloniki, Greece, say: "Only the future can tell whether renal denervation will change the way we treat hypertension, whether it will be an additional arsenal in our therapeutic armamentarium, or just another shooting star. However, the exciting results of the Symplicity study generate great expectations, and the investigators have paved the way for interventional management of patients with resistant hypertension."

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Professor Murray D Esler, Baker IDI Heart and Diabetes Institute, Melbourne, Australia. T) +61 409 178 058 E) murray.esler@bakeridi.edu.au (Prof Esler will be staying at the Palmer House Hilton Hotel in Chicago for the AHA meeting: T) + 1 312 726 7500)

Professor Michael Doumas, Veteran Affairs Medical Centre, George Washington University, Washington, DC, USA. T) +30 694 700 600 1 E) michalisdoumas@yahoo.co.uk

For full Article and Comment, see: http://press.thelancet.com/symplicity.pdf

NOTE: THE ABOVE LINK IS FOR JOURNALISTS ONLY; IF YOU WISH TO PROVIDE A LINK TO THE FREE ABSTRACT OF THIS PAPER FOR YOUR READERS, PLEASE USE THE FOLLOWING, WHICH WILL GO LIVE AT THE TIME THE EMBARGO LIFTS: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)62039-9/abstract

Note to editors: *a fall of 10mm Hg was a secondary endpoint in the trial. This is a BP reduction sufficient in degree to be shown in epidemiological studies to confer material protection against heart attacks and strokes.


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