Renal Denervation Helps Resistant Hypertensives

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CHICAGO—Catheter-based renal denervation significantly decreases blood pressure (BP) in patients with treatment-resistant essential hypertension, according to results released at the American Heart Association Scientific Sessions 2010 and simultaneously published online in The Lancet.

Cardiologist Murray D.  Esler, MD, Associate Director of the Baker IDI Heart and Diabetes Institute in Melbourne, Australia, presented findings in 106 treatment-resistant hypertensive patients who had been randomized to undergo renal denervation and continue their prior antihypertensive therapy or to continue their prior therapy only. 

Catheter-based renal denervation is a minimally invasive procedure that uses a catheter to ablate renal sympathetic nerves, which are frequently activated in chronic hypertension. Surgical renal denervation has been shown to reduce BP in animal models of hypertension.   

“Blood pressure levels remain high in about half of hypertensive patients even though effective medications are available along with programs designed to help patients with lifestyle modifications,” Dr. Esler pointed out.

“Based on our findings, we believe that in patients whose systolic blood pressure is 160 to 200 mm Hg even though they are taking multiple antihypertensive medications, catheter-based renal denervation is a logical next step provided that long-term safety is assured and all the evidence to date shows that this is indeed a safe procedure.”

Patients enrolled in the 24-center Symplicity HTN-2 trial had a baseline systolic pressure of 160 mm Hg or more despite adherence to a regimen of three or more antihypertensive drugs. To be eligible for enrollment, patients with concurrent type 2 diabetes had to have a baseline systolic pressure of 150 mm Hg or higher. The trial excluded patients who had renal artery stenosis or who had undergone a prior renal artery intervention. The study's primary efficacy endpoint was the change in supine office-based measurement of systolic blood pressure at six months.

At six months, BP in the renal denervation group had decreased significantly by 32/12 mm Hg from a mean baseline level of 178/96 mm Hg. BP remained unchanged in control patients. In addition, 84% of the renal denervation group had a decrease in systolic pressure of 10 mm Hg or more versus 35% of controls, a significant difference between the groups.  

The researchers observed no serious device- or procedure-related adverse events.

In addition, there were no changes in renal function with denervation, even in patients with mild to moderate renal failure.  The findings suggest that the procedure itself and associated hemodynamic changes have no adverse renal effects, Dr. Esler said.

Several patients were able to withdraw entirely from their antihypertensive medications.

“I think there's a bit of a turf war as to who would perform the procedure,” Dr. Esler said.  “In the trial, the procedure was done by interventional cardiologists and interventional radiologists. But I am sure that any proceduralist who is used to doing invasive procedures could be trained to perform this procedure competently.”

Although his team had theorized that sympathetic nerve regrowth could “mitigate” treatment effects, the antihypertensive effect of renal denervation was maintained for up to two years in pilot studies, Dr. Esler said.

Finally, he emphasized that while he is strongly encouraged by the results, some unknowns remain. Future studies will test the efficacy of renal denervation in milder hypertension and also in populations that have not yet been examined, including African-American, Hispanic, and Asian patients. Researcher also will examine whether catheter-based renal denervation shows benefit in other diseases in which the renal sympathetic outflow is activated, including cardiac failure, chronic kidney disease, and cirrhoses with ascites. 

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