Changes in heart rate variability in response to treatment with electroconvulsive therapy

Background: Objective methods are needed to determine when to terminate a course of electroconvulsive therapy (ECT). Heart rate variability (HRV) has proven predictive value for patients with cardiac and neurologic disorders and correlates with depression severity and treatment effects. Variable changes in HRV after ECT have been reported. Methods: Holter monitoring was performed before and after ECT in 11 patients with depression. Measures of HRV were obtained from these recordings and the relationships between HRV and treatment outcome was analyzed. Response to ECT was measured by the 24-item Hamilton Rating Scale for Depression. Results: Standard deviation of interbeat intervals (SDNN, a measure of HRV) increased in subjects who improved with ECT (P < 0.02) but not in those who became confused and agitated. Among those patients who acutely responded to ECT, SDNN increased (P < 0.05) in subjects with a sustained response but not in subjects who relapsed within 3 weeks. SDNN was significantly lower in the rapid relapse group at baseline (P < 0.05) and after ECT (P < 0.05) compared with the group with a sustained response. Conclusions: Low baseline HRV is associated with rapid relapse of depression after ECT. Both high baseline HRV and increasing HRV predict a sustained outcome. Further research is necessary to support these findings and to clarify if the serial measurement of HRV during ECT may help to determine the optimal number of treatments for each patient.