Renal denervation fails to lower blood pressure in critical test
By Gene Emery
March 29 (Reuters) - Patients treated by renal artery denervation were no more likely to see their blood pressure decline than those who received a fake therapy in a major clinical trial, calling into question a therapy used in more than 80 countries to treat high blood pressure that doesn't respond to drugs.
The study was considered a key test of the intervention in which nerve connections between the heart and kidney were disrupted in an effort to lower blood pressure as prior trials did not include a proper blinded control group for efficacy comparison.
The study, released on Saturday by the New England Journal of Medicine and presented at the meeting of the American College of Cardiology in Washington, "brings the renal-denervation train to a grinding halt," said Dr. Franz Messerli and Dr. Sripal Bangalore in a Journal editorial.
Because earlier tests of the technique did not involve treating some patients with sham therapy, "placebo effect may well explain all or most of the blood pressure differences" in two key trials, known as SYMPLICITY HTM-1 and HTN-2.
The new blinded test, called SYMPLICITY HTN-3, was financed by Medtronic Inc, which makes the equipment used in the study. Boston Scientific Corp and St. Jude Medical Inc also make renal denervation equipment.
"We wanted to see whether this would offer something beyond what the best medical therapy can," chief investigator Dr. Deepak Bhatt of Brigham and Women's Hospital in Boston said in a telephone interview. "It should give doctors pause to what they're doing, at a minimum."
Renal denervation involves threading a catheter into the arteries feeding the kidney and using radiotherapy to destroy some of the nerves believed to control blood pressure.
About 10 percent of people with high blood pressure are resistant to conventional therapy and are candidates for the treatment, which is still regarded as experimental in the United States. It is approved in parts of Europe, South America, Australia and Canada. Continued...