Cervicothoracic Transcutaneous Electrical Nerve Stimulation Attenuates Cardiac Sympathetic Overdrive in Heart Failure: A 123l-MIBG Myocardial Scintigraphy, Randomized Double-Blind Crossover Trial

Introduction: Cardiac sympathetic drive provides inotropic support to the failing heart and preserves cardiovascular homeostasis. Nonetheless, as myocardial insult evolves, this compensatory response leads to a progressive decline in contractile function, increases the vulnerability to arrhythmias and constitutes an independent mortality predictor. Despite advanced pharmacological therapies, side effects and persistent cardiac sympathetic overdrive highlights the modulation of the adrenergic system as a primary target for non-pharmacological strategies in the heart failure (HF) treatment. In this scenario, we will propose cervicothoracic transcutaneous electrical nerve stimulation (TENS) as a non-pharmacological therapy to attenuate cardiac sympathetic overdrive in patients with heart failure. Methods: In this prospective, randomized, sham-controlled, double-blind crossover trial, ten (10) HF patients under optimal pharmacological treatment will be randomly assigned to either an in-home cervicothoracic transcutaneous electrical nerve stimulation therapy (TENS: 30 min twice a day with 80 Hz frequency and pulse duration of 150 μs) or a sham control intervention (SHCI) for two weeks. Following a two-month washout phase from TENS/SHCI, patients crossed over and started the opposite condition. Washout rate and heart-to-mediastinum ratio (planar 123l-metaiodobenzylguanidine myocardial scintigraphy images), indexes of cardiac sympathetic activity and innervation density, muscle sympathetic nerve activity (microneurography) and brachial artery blood flow (Doppler ultrasound) during dynamic handgrip exercise will be obtained at the beginning and end of each condition.