Predicting Antidepressant Response to Transcranial Magnetic Stimulation With Heart Rate Variability

Treatment resistant depression (TRD) in major depressive disorder (MDD) is defined as poor response to ≥2 antidepressant treatment trials. Repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to have breakthrough antidepressant efficacy in this population, with around a 50% response rate. Yet, it is not possible to predict which patients will show sufficient improvement with TMS a priori. Heart rate variability (HRV) measures the temporal variability between successive heartbeats and reflects the balance of sympathetic and parasympathetic nervous system processes. This balance is associated with emotion regulation and other autonomic processes thought to be impaired in MDD and TRD. Moreover, reductions in HRV have been reported in patients with TRD.