A promising treatment for severe high blood pressure has failed in a large, rigorous study, doctors reported on Saturday.

The treatment, called renal denervation, involves threading a tube through blood vessels into the renal arteries, then zapping them with radio-frequency energy to kill nerve endings.

The procedure was thought to be a lifesaver for people whose high blood pressure could not be lowered even with multiple drugs. Uncontrolled hypertension increases the risk of strokes, heart attacks and other problems.

In the United States, 67 million people have high blood pressure, and it resists treatment in about 10 percent of them.

The new findings on denervation are likely to surprise many doctors, because previous case reports and studies had found astounding drops in blood pressure after the treatment — as much as 30 millimeters of mercury in systolic pressure, the top number in a blood pressure reading.

“I think many people were anticipating there would be some degree of reduction and will be surprised there wasn’t anything,” said Dr. Deepak L. Bhatt, an author of the study and executive director of interventional cardiovascular programs at Brigham and Women’s Hospital in Boston.

But the negative finding should not kill research into denervation, Dr. Bhatt said, because performing the procedure in a different way might work.

The idea behind denervation came from studies decades ago involving surgical procedures that did lower blood pressure — but too much, so that patients would faint when they tried to get out of bed.

The new study, published in The New England Journal of Medicine, was presented at a cardiology meeting in Washington.

The earlier reports led to great enthusiasm for denervation in Europe and other parts of the world, and it has been approved in more than 80 countries and performed on thousands of patients. It has not been approved in the United States, so in most cases, patients in this country could receive it only by participating in clinical trials.

“You have to perhaps congratulate the Food and Drug Administration that they were not as eager to approve this procedure based on the little evidence there was, as opposed to the Europeans and the Australians,” said Dr. Franz Messerli, a cardiologist and hypertension expert at Mount Sinai Roosevelt Hospital in Manhattan, who wrote an editorial accompanying the new report.

The study included 535 patients with treatment-resistant hypertension. All continued taking their blood pressure drugs and agreed to undergo either the denervation treatment or a “sham” procedure closely resembling it. Patients were not told whether they had gotten the real treatment or the fake one.

Earlier studies did not include a sham-treatment group. The reason for using it this time was to try to control for the power of suggestion — the idea that people’s blood pressure might go down simply because they thought they had been treated. (This is the same reasoning used in drug studies with control groups that are given placebos.)

Six months later, both groups experienced drops in blood pressure, but there was no significant difference between those who had undergone the denervation and those who had received the sham procedure.

“It is absolutely a landmark study,” Dr. Messerli said. “I hope it will have an impact and will override some of the zeal of the European investigators.”

Written by Denise Grady and published by the New York Times, March 29, 2014.

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