Power spectrum of the QRS complex in patients with panic disorder and normal controls.

We performed spectral analysis on the QRS complex of the electrocardiogram obtained using standard limb leads, sampled at 500 Hz with 12 bit precision in 20 normal subjects and 15 patients with panic disorder. We divided the frequency range of the QRS into two bands based on spectral patterns before and after the postural challenge-mid frequency (MF): 7.8-20 Hz; and high frequency (HF): 21-250 Hz. Postural change from supine to standing produced a significant increase in absolute (P = 0.003) and relative HF power (P = 0.00001). Patients with panic disorder had a significantly decreased QRS HF power (P = 0.003). The increase in QRS HF power may have been due to the shortening of the QRS interval in standing posture. The decreased QRS HF power in patients with panic disorder should be further investigated due to the recent reports of an association of phobic anxiety and fatal coronary heart disease, and the possible association of decreased high frequency components of QRS in myocardial infarction.