– Study flowchart. taVNS: transcutaneous auricular vagus nerve stimulation; Sham group: simulation; HFrEF: heart failure with reduced ejection fraction; SDNN: standard deviation of all normal R-R intervals recorded in a time interval; rMSSD: square root of the mean squared differences between adjacent normal R-R intervals over a time interval (milliseconds).
stroke, mitral regurgitation
AORTIC STENOSIS, STROKE, HEART, MITRAL REGURGITATION

Outpatients with compensated or recovered HF NYHA classes I-IV, receiving optimal pharmacological therapy in the last 3 months.Age over 18 years old.LVEF (left ventricle ejection fraction) less than 50% documented by echocardiography.
Patients hospitalized for HF or using intravenous therapy for HF in the last 30 days.Patients with severe mitral regurgitation or severe aortic stenosis.Heart surgery or angioplasty, or stroke within the last 3 months.Pacemaker users.Patients with an LVEF ≥ 50%.