The effect of amitriptyline, doxepin, fluvoxamine, and paroxetine treatment on heart rate variability.

A total of 32 unmedicated patients with episodes of major depression (DSM-III-R) and 32 normal control subjects matched for age and sex were tested for heart rate variability (R-R variation) while resting and during deep breathing. Compared with the group of healthy subjects, the depressed patients showed no abnormalities before therapy. The patients were randomly allocated for treatment with 150 mg of amitriptyline per day (N = 8), 150 mg of doxepin per day (N = 8), 150 mg of fluvoxamine per day (N = 8), and 20 mg of paroxetine per day (N = 8). During treatment with either amitriptyline or doxepin, the coefficients of variation at rest and during deep breathing, which are largely independent of heart rate, had significantly decreased after 14 days (p = 0.012), whereas patients treated with fluvoxamine or paroxetine showed no significant changes of heart rate variability parameters after 14 days. The implications of these findings are discussed.