The effects of venlafaxine on heart rate variability in healthy subjects

Dr. Siepmann, Timo , Aykac, Volkan , Prof. Dr. Siepmann, Martin , Prof. Dr. Kirch, Wilhelm. Institute of Clinical Pharmacology, Medical Faculty, Technical University, Fiedlerstr. 27, 01307 Dresden, Germany.

Antidepressant treatment may impair heart rate variability (HRV). This randomized, double blind placebo-controlled study examined the effects of venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor (SSNRI), on parameters of heart rate variability in humans. 12 healthy male subjects aged 23 to 32 years (26 ±3 years mean ± sd) orally received 37.5 mg venlafaxine b.i.d. for 7 days and subsequently 75 mg b.i.d. for another 7 days. After a 14-day washout phase, placebo was administered to the subjects for 14 days under randomized double-blind cross over conditions. An ECG was conducted under resting conditions and during paced breathing (6 seconds of inspiration and 4 seconds of expiration) prior to start of medication and after the last dose was given. Heart rate analysis was carried out with the computer program Chart® (AD Instruments, Castle Hill, Australia). The root mean square of successive differences (RMSSD) of R-R intervals significantly decreased 3 hours following last dosing with venlafaxine (ANOVA P< 0.01, Chi-Square=27.3) whereas heart rate and spectral power values in the high frequency (HF), low frequency (LF) and very low frequency (VLF) ranges did not change. In conclusion, venlafaxine may impair HRV when given subchronically at therapeutic doses.