123I-Metaiodobenzylguanidine myocardial scintigraphy in panic disorder

Although autonomic function has been investigated in panic disorder, previous studies have not yet revealed a consistent autonomic change in this disease. The purpose of this study was to evaluate the cardiac sympathetic function in panic disorder using (123)I-metaiodobenzylguanidine ((123)I-MIBG).

Myocardial imaging using (123)I-MIBG was performed on 9 patients with panic disorder (7 men, 2 women; mean age, 37.4 +/- 13.2 y) and 11 control subjects (11 men; mean age, 37.6 +/- 9.3 y). Early (30 min) and delayed (4 h) planar images were taken after the injection of 111 MBq (123)I-MIBG. The mean counts in the whole heart and the mediastinum were obtained from the early and delayed images to calculate the heart-to-mediastinum count ratios (H/M ratios) and the myocardial washout rate.

The (123)I-MIBG H/M ratios of the patients with panic disorder were 1.80 +/- 0.16 for the early images and 1.86 +/- 0.30 for the delayed images, which were significantly lower than those of the control subjects (2.15 +/- 0.15 [P = 0.001] and 2.26 +/- 0.21 [P = 0.009], respectively). The (123)I-MIBG washout rate from the heart in the patients with panic disorder (33.8% +/- 6.9%) was significantly higher than that in the control subjects (27.8% +/- 3.5%) (P = 0.02).

(123)I-MIBG myocardial scintigraphy demonstrated impairment of cardiac sympathetic function in panic disorder. The results suggest that (123)I-MIBG imaging could become a useful tool for analyzing the pathophysiology of panic disorder.