The goal for systolic blood pressure (the top number in a blood pressure reading) was under 140 mmHg. At monthly visits, if a patient's target was not met, the voltage was upped to further lower blood pressure.
Systolic blood pressure dropped in both groups, the researchers reported. Forty-one percent of patients with the device achieved target levels after six months, and more than half (54 percent) met the goal after the 12-month mark.
The researchers were also surprised by a placebo effect noted in the other group: about one-fifth of people who weren't getting shocks still met their target for lowered blood pressure during the first six months, or control phase, while 46 percent achieved the target by the end of the study.
Overall, "reductions in [systolic blood pressure] at 12 months were at least 50 percent of those seen at six months, demonstrating a sustained response," the researchers wrote.
In both time periods, both groups saw their diastolic blood pressure (the lower number in a reading) drop as well.
At the end of the study, "there was an 88 percent responder rate, a 35 mmHg blood pressure drop and a decrease in left ventricular mass," the researchers wrote, explaining that chronic hypertension enlarges the heart's left ventricle.
"The data showed that the therapy significantly reduced blood pressure in patients with resistant hypertension," they said.
Cardiologists not involved in the study did offer some caveats, however.
Dr. Nieca Goldberg, director of the women's heart program at NYU Langone Medical Center in New York City, called the treatment "a novel approach" for people unable to tolerate or benefit from high
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