Anxiety and vagal control of heart rate

Objective: Prospective studies have demonstrated that anxiety predicts sudden cardiac death, but the mechanism underlying this increased risk is unclear. This study examined whether anxiety is associated with reductions in vagal control of heart rate in healthy volunteers. Method: Trait anxiety (T-ANX) was measured, using the Spielbeger State-Trait Anxiety Inventory (STAI), in 93 healthy men and women 25 to 44 years of age. Power spectral analysis was used to measure two indices of vagal control: baroreflex control of heart rate (BRC) and respiratory sinus arrhythmia (RSA). Results: High trait anxiety (T-ANX > 41, N = 23) was associated with significantly reduced vagal control of the heart, compared with low trait anxiety (T-ANC < 31, N = 22), as indicated by a 36% reduction in BRC (p < .001) and an 8% reduction in RSA (p < .05). Furthermore, T-ANX scores were negatively correlated with levels of BRC (r = -.30, p < .005), and levels of RSA (r = -.26, p < .05). Conclusions: These findings provide evidence that trait anxiety is associated with reductions in vagal control of the heart. Additional studies are needed to examine whether low vagal control is involved in the increased risk of sudden cardiac death associated with anxiety.