In about a third of all patients prescribed medications to lower elevated blood pressure (BP) levels, the drugs do not work or patients fail to take them as directed.
“There are a variety of effective medications for lowering blood pressure, but many people need to take several drugs to control their hypertension, which can have side effects. In addition, many people simply don’t want to take additional medications and are poorly adherent to them,” says Ajay Kirtane, MD, professor of medicine at Columbia University Vagelos College of Physicians and Surgeons, and an interventional cardiologist at NewYork-Presbyterian/Columbia University Irving Medical Center.
These practical issues indicate a need for alternative or additional therapeutic approaches to help patients get their blood pressure under control.
A new study reports brief pulses of ultrasound at nerves near the kidney shows clinically significant drops in blood pressure (BP) in drug-resistant hypertensive patients. The procedure has the potential of complementing pharmaceutical therapeutic approaches, particularly in patients who find it difficult to manage multiple medications for BP.
These findings were presented at the American College of Cardiology conference on May 16 and simultaneously published in The Lancet in an article titled, “Ultrasound renal denervation for hypertension resistant to a triple medication pill (RADIANCE-HTN TRIO): a randomised, multicentre, single-blind, sham-controlled trial.”
In a clinical trial called RADIANCE-HTN TRIO (ClinicalTrials.gov, NCT02649426), led by researchers at Columbia University Vagelos College of Physicians and Surgeons and NewYork-Presbyterian, the safety and efficacy of the procedure called “renal denervation” was tested in patients who did not respond to a triple cocktail of medications. All patients were switched to the same medication regimen for hypertension where they took a single pill that combined three commonly used antihypertensive drugs.
“In our study, 80% of patients continued to take their medication as directed, and while that’s a good adherence rate, it still means that one in five patients weren’t adherent to the medication regimen,” says Kirtane.
Of 136 patients whose blood pressure remained high after four weeks on the new regimen, 69 were treated with renal denervation and 67 had the sham procedure.
The results demonstrate a daytime drop in BP of 8 points compared to a 3-point drop in patients who were treated with a sham procedure, and a nighttime drop in BP by 8.3 points in the treatment group versus 1.8 points in the sham group, after two months’ treatment.
“For patients with drug-resistant hypertension, a drop in blood pressure of 8 points—if maintained over longer-term follow-up—is almost certainly going to help reduce the risk of heart attack, stroke, and other adverse cardiac events,” says Kirtane, who is co-principal investigator of the trial.
Kidney regulate the volume of water in the circulation and plays a significant role in regulating BP. Renal denervation uses ultrasound to disrupt signals from hyperactive nerves in the renal arteries. The minimally invasive therapy is delivered via a catheter that is threaded through an artery in the leg and delivers two to three short blasts of ultrasound to nerve fibers close to the renal artery.
Several existing medications reduce renal nerve activity to reduce blood pressure.
“But unlike medications, which are only effective when you take them, renal denervation is a therapy that’s always ‘on,'” Kirtane says.
This experimental treatment has not been approved for use by the FDA and is only available through clinical trials. The trial will follow patients for five years to determine if the drop in blood pressure is maintained over time. Whether renal denervation can be used in other patient populations such as older patients with hypertension or those with chronic kidney disease will require additional studies.
