St Jude Medical Inc said on Monday its procedure that deadens nerves near the kidneys helped lower blood pressure in a small study of patients whose hypertension could not be controlled with drugs.

Patients in the study who were treated with the Enlightn renal denervation system saw an average reduction of 28 points in systolic blood pressure, which is the first number expressed in a reading, after 30 days. At six months, the 46 patients who received the treatment maintained an average systolic blood pressure reduction of 26 mmHg points.

The results were presented at the annual meeting of the American Heart Association in Los Angeles.

Patients enrolled in the study had an average blood pressure of 176/96 mmHg despite being treated with multiple medications to manage the condition. No serious side effects were reported, St Jude said.

Normal blood pressure is below 120/80 mmHg. Hypertension, or high blood pressure, is a reading above 140/90 mmHg.

Renal denervation is a procedure in which a thin, flexible catheter is threaded through the body to the renal sympathetic nerves near the kidneys. Radiofrequency energy is delivered to disrupt the nerve activity, relieving high blood pressure.

Millions of people have hypertension that is resistant to drugs, putting them at risk of heart attacks and stroke.

The new therapy is not yet approved in the United States, but several products are already available in Europe.

Device makers that have already received approval to sell hypertension devices in Europe include Medtronic, the front-runner, St Jude, Covidien, ReCor Medical and Vessix Vascular.

St Jude shares were up 29 cents, or less than 1 percent, at $38.80 in afternoon trading on the New York Stock Exchange.

(Reporting By Susan Kelly and Debra Sherman in Chicago; Editing by Gerald E. McCormick, Leslie Adler and Jim Marshall)

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(Reuters)