Noninvasive vagus nerve stimulation promising for treating postural tachycardia syndrome

Low-level transcutaneous stimulation of the auricular branch of the vagus nerve at the tragus is anti-inflammatory and antiarrhythmic in humans and animals. Preliminary studies demonstrated that transcutaneous vagus nerve stimulation (tVNS) benefits animal models of POTS. Stavros Stavrakis, University of Oklahoma Health Sciences Center, Oklahoma, USA, and colleagues conducted a double-blind, sham-controlled, randomized clinical trial to investigate the effect of tVNS on POTS over 2 months relative to sham stimulation.

For this purpose, the researchers delivered transcutaneous vagus nerve stimulation (20 Hz, 1 mA below discomfort threshold) using an ear clip attached to either the tragus (active; n = 12) or the ear lobe (sham; n = 14) daily for 1 hour over 2 months. Postural tachycardia was evaluated during the baseline and 2-month visit. Heart rate variability based on a 5-minute electrocardiogram, antiautonomic autoantibodies, and serum cytokines were measured at the respective time points. The mean age of the participants was 34 ± 11 years (100% female; 81% Caucasian).

The study revealed the following findings:

• Adherence to daily stimulation was 83% in the active arm and 86% in the sham arm.
• Postural tachycardia was significantly less in the active arm compared with the sham arm at two months (mean postural increase in heart rate 17.6 ± 9.9 beats/min vs 31.7 ± 14.4 beats/min).
• Antiadrenergic autoantibodies and inflammatory cytokines were lower in the active arm compared with the sham arm at 2 months.
• Heart rate variability was better in the active arm.
• No device-related side effects were observed.

"Our findings support the emerging paradigm of noninvasive neuromodulation for POTS treatment," the researchers wrote. "Mechanistically, this effect appears to be related to a reduction of inflammatory cytokines and anti-autonomic autoantibodies, and an improvement in autonomic tone."

"Further studies are warranted," they concluded.

Reference:

Stavrakis S, Chakraborty P, Farhat K, Whyte S, Morris L, Abideen Asad ZU, Karfonta B, Anjum J, Matlock HG, Cai X, Yu X. Noninvasive Vagus Nerve Stimulation in Postural Tachycardia Syndrome: A Randomized Clinical Trial. JACC Clin Electrophysiol. 2023 Nov 10:S2405-500X(23)00806-X. doi: 10.1016/j.jacep.2023.10.015. Epub ahead of print. PMID: 37999672.