Effect of Fluoxetine and Escitalopram on Heart Rate Variability (HRV) and Serum Potassium Level in Patients of Depression and Anxiety Disorders

Background: The present study was conducted to generate data regarding the effect of fluoxetine as an anti-depressant and escitalopram as an antianxiety agent on heart rate variability (HRV). There is a scarcity of data regarding the correlation between selective serotonin reuptake inhibitors (SSRIs) and serum potassium levels.

Purpose: To find out the effect of SSRIs on HRV, and whether it is either dependent or independent of serum potassium level.

Materials and Methods: In this prospective, open-label, observational study, 70 participants were enrolled and divided into two groups, the fluoxetine group (n = 35) and the escitalopram group (n = 35) suffering from depression and anxiety, respectively. Parameters, like HRV, serum potassium level, heart rate, respiratory rate, and blood pressure, were measured baseline and after the first, second, and third months of treatment. HRV was calculated by root mean square deviation of successive differences between adjacent RR intervals (RMSSD). ECG (electrocardiogram) was recorded by Physio Pac Digital Polygraph software. All values were expressed as mean ± SD, and statistical analysis was done by using the repeated measure analysis of variance (ANOVA) test with Greenhouse–Geisser correction, post hoc analysis with Bonferroni correction, and SPSS 20.0 software.

Results: Among a total of 70 participants, post hoc tests using the Bonferroni correction showed a statistically significant difference between the HRV of the pretreatment group and after the second, and third month of fluoxetine therapy (p < .05). In the escitalopram group, the Bonferroni correction showed a significant difference between the HRV of the pretreatment and third-month value (p < 0.05). Repeated measure ANOVA with Greenhouse–Geisser correction showed no statistical significance of serum potassium at different time points (p > 0.05). There were also no significant changes in heart rate, respiratory rate, and blood pressure at different points of time in both groups. Pearson’s correlation coefficient test for a relationship between HRV and serum potassium was negative at different time points.

Conclusion: Fluoxetine significantly increased HRV from the pretreatment value to the second and third months of treatment, whereas in the escitalopram group of participants, the third-month value of HRV was increased compared to the first month. The effect of SSRIs on HRV was independent of serum potassium levels at different time points suggesting that the effect of SSRIs on HRV was independent of serum potassium level.