Tragus Stimulation to Prevent Atrial Fibrillation After Cardiac Surgery

This was a single-blind study where patients were randomized tragus stimulation versus sham procedure and remained blinded to their treatment allocation. Both treatment options utilized similar equipment, namely the use of alligator clips which will be placed on the tragus and earlobe of the right ear for patients.

Prior to cardiac surgery, the discomfort threshold of both left and right tragus stimulation was determined for all participating patients. Intermittent electrode signals, or microcurrents, were delivered at 20 Hz with100 µsec pulse width with variable microampere (mA) output. The discomfort threshold was defined as the stimulation intensity in mA at which point patients experience discomfort. The stimulation intensity used in the study was set below the sensation and discomfort threshold. The clip was placed on the patient's ear at the end of surgery. Stimulation then continued, one ear alternating with the other, every 4 hours for a total of 48 hours. If the patient showed any sign of discomfort from stimulation, the intensity of stimulation was reduced to a level at which signs of discomfort disappears.

Follow-up was performed with a 14-day event monitor at the time of discharge, as clinically indicated. Echocardiography were assessed prior to study initiation and when clinically available in follow-up.

Inclusion criteria

• Patients ≥18 years of age, <90 years of age
• Estimated life expectancy of at least 1 year at the time of enrollment
• History of sinus rhythm or paroxysmal atrial fibrillation

Exclusion criteria

• Patients ≥90 years of age, <18 years
• Patients with known prior history of persistent or permanent AF
• Atrial Fibrillation occurrence within the last 24 hours of procedure
• Urgent or Emergency cases
• Pregnant patients
• Patients undergoing the following cardiac procedures: heart transplant, pulmonary thromboendarterectomy, isolated aortic arch procedures, congenital hear disease, ventricular assist device insertion, extracorporeal membrane oxygenation insertion, and surgical AF ablation
• Antiarrhythmics prior to surgery (Class I and Class III)
• High degree atrioventricular block requiring temporary pacing
• Prior maze procedure for the treatment of AF