Heart rate and QT variability in children with anxiety disorders: A preliminary report

This study compared beat-to-beat heart rate and QT variability in children With anxiety disorders (n=7) and normal controls (n=15) by using an automat ed algorithm to compute QT intervals. An increase in QT variability appears to be associated with a higher risk for sudden cardiac death. A decrease i n heart rate variability is also linked to significant cardiovascular event s. Supine detrended QT variability, QT variability corrected for mean QT in terval, and QTvi (a log ratio of QT variance normalized for mean QT over he art rate variability normalized for mean heart rate) were significantly hig her in children With anxiety compared to controls (P<0.05). The largest Lya punov Exponent (LLE) of heart rate time series Was significantly lower (P<0 .05) in children With anxiety compared to controls. These findings suggest a relative increase in sympathetic activity and a relative decrease in cal dine vagal activity in children With anxiety disorders, and are discussed i n the context of the effects of tricyclics on cardiac autonomic function in children, and the rare occurrence of sudden death during tricyclic antidep ressant treatment. (C) 2001 Wiley-Liss, Inc.