Paroxysmal sinus tachycardia (PST) due to anxiety. The patient, a 34 y/o woman, was referred for evaluation of postural tachycardia syndrome (POTS). During montage in supine position before placing the blood pressure sensor (i.e., why the initial portion of recording is missing), she became very anxious after she was informed that she will be tilted in several minutes. The anxiety was associated with transient tachycardia 170 BPM, elevated BP, and CBFv (green ovals). Similar pattern (transient tachycardia, elevated BP, and CBFv) was observed at the onset of the tilt (blue oval). The supine tachycardia of similar character to that of the tilt confirms that this is not POTS but IST. Furthermore, the tachycardia is usually sustained and/or it is progressively increased during the tilt in POTS. CBFv is usually unchanged or decreased in POTS during the tilt.