Differential actions of antidepressant treatments on cardiac autonomic alterations in depression: A prospective comparison.

BACKGROUND: Patients with depression have higher rates of cardiac morbidity and mortality. Alterations of cardiac autonomic functions associated with depression may partly explain this. Prospective studies comparing the effects of antidepressants on these abnormalities are limited due to confounding factors and co-morbidities.
METHODS: Cardiac autonomic functions were studied in antidepressant naïve patients with major depression (without co-morbid medical or psychiatric disorders) before and after treatment with repetitive transcranial magnetic stimulation (rTMS; n=30), specific serotonin reuptake inhibitors (SSRIs; n=32) and tricyclic antidepressants (TCAs; n=32). Conventional autonomic function tests and time- and frequency-domain measures of heart rate variability (HRV) were measured using standard procedures. Changes in autonomic functions were compared across the three treatment groups using repeated measures analysis of variance (ANOVA) using sex and age as covariates.
RESULTS: Depression improved by comparable extent across patients treated with the three treatments. Overall, there was no change in cardiac autonomic functions. However, significant group×occasion interactions were noted for HRV measures. Both time- and frequency-domain HRV measures showed increase with rTMS and decrease with TCAs; they remained virtually unchanged with SSRIs. LIMITATIONS: One of the major limitations of our work being we could not randomize the treatment groups.
CONCLUSIONS: The effects of antidepressant treatments on cardiac autonomic function abnormalities found in depression vary with the mode of treatment used. Long-term clinical implications of these effects on cardiac health of patients with depression need further studies.