Effect of paroxetine on heart rate variability in panic disorder: analysis of holter records

Some evidence suggests increased cardiovascular morbidity in patients with panic disorder. Our previous reports suggest decreased heart rate variability in patients with panic disorder, with a relative increase in cardiac sympathetic function. We have previously found that patients with panic disorder have significantly decreased ULF power and total powers during sleep compared to controls. Decreased ULF and VLF powers are linked to sudden death and increased cardiovascular morbidity. In this report, we investigated the changes in cardiac autonomic function in patients with panic disorder after successful treatment of their panic attacks with Paroxetine (10-30 mg per day). This preliminary report used Holter records of ECG in 8 patients (females, age: 38.4 ± 9.8 years) before and after treatment with Paroxetine. We used customized software to download and edit the R-R interval data from the Delmar 750 Holter System. All data were visually inspected to make sure there were no missed beats or premature beats. In addition to the 24-hour data, two 20,000 second segments were analyzed, one reflecting the day time activities and the other, sleep records. We performed spectral analysis using Fourier Transform to quantify the ULF (<0.0033 Hz), VLF (0.0033-0.04 Hz), LF (0.04-0.15 Hz) and HF (0.15-0.5 Hz) powers using a rectangular data window integrating the powers in these bands. We quantified both absolute and relative powers. The units for power are in msec squared. There was no significant change in the mean heart rate after treatment (88.3 vs 89.6 bpm). There was no significant change in both LF and HF powers of heart period during sleep after treatment, while there was an increase in the ULF power (p<0.1). However, the relative LF power was decreased (p<0.05) while there was a significant increase in the relative ULF power (p<0.01) during sleep after treatment. These data suggest that Paroxetine treatment may be associated with beneficial effects on cardiac function in addition to its effectiveness in treating panic attacks. We will present data from a lager sample of patients treated with Paroxetine.