Is baroreflex activation therapy safe for the kidney?

The current study explores the effect on kidney function of baroreflex activation therapy, a treatment for high blood pressure (hypertension).

The baroreflex or the baroreceptor reflex is a normal mechanism that helps the body maintain a normal blood pressure (BP) by decreasing BP when it gets too high. Baroreflex activation therapy (BAT) is a treatment for patients with drug-resistant hypertension (hypertension that does not respond to at least 3 antihypertensive drugs at maximum dosage). In BAT, a device that delivers electrical impulses is implanted underneath the collarbone and electrically activates the baroreflex, which lowers BP. The kidneys also play an important role in BP regulation, and BP, in turn, can affect the function of the kidneys. Therefore, it is important to understand how BAT affects kidney function. Kidney function is usually measured through the value of the serum creatinine and the estimated Glomerular Filtration Rate or eGFR. A high creatinine level and low eGFR means a compromised kidney function. The current study analyzed the effects on kidney function of BAT in patients with drug-resistant hypertension.

This phase III clinical trial included 322 patients with drug-resistant hypertension who had a BAT device implanted. 236 patients started BAT 1 month after the implantation of the device (immediate BAT), and the remaining 86 patients had the BAT device activated six months later (late BAT). BP, serum creatinine and eGFR were measured at the beginning of the study and at 6 and 12 months after the implantation of the BAT device. Results showed that in the immediate BAT group, there were significant drops in BP levels at both 6 and 12 months following the start of BAT. At 6 months, serum creatinine increased from 78 to 84 µmol/L and the eGFR decreased from 92 to 87 mL/min in the immediate BAT group. These results, however, did not change any further at 12 months. Patients in the late BAT group had similar results with patients in the immediate BAT group.

In summary, this research showed that continuous BAT initially decreased kidney function (at 6 months). However, at 12 months no further decline in kidney function was found, indicating that the initial change in kidney function was due to the drop in BP associated with BAT. Therefore, researchers conclude that BAT is a safe and effective treatment for patients with drug-resistant hypertension.

However, this study followed patients for only 12 months following the start of BAT. Further measurements of kidney function of these patients, for longer periods of time, are necessary in order to confirm the long-term effects of BAT on kidney function.

Discuss with your physician the risks and benefits of baroreflex activation therapy.