Background: Although depression has been associated with increased mortality in patients after acute myocardial infarction (AMI), little is known about the effects of depression on autonomic nervous system control of heart rate. This study evaluated whether depression is associated with impaired baroreflex sensitivity (BRS) in patients with AMI.
Methods: Two hundred four hospitalized patients with AMI were evaluated 6 +/- 3 (mean +/- SD) days after AMI. BRS was assessed using cross-spectral analysis to measure baroreceptor-mediated R-R interval oscillations. Depression was determined using the Diagnostic Interview Schedule, and severity of depressive symptoms was measured with the Beck Depression Inventory. In order to adjust for possible differences in anxiety, we also measured state anxiety using the Spielberger State Anxiety Inventory.
Results: Depression was not significantly related to BRS. However, anxiety was significantly related to low BRS in multivariate analysis, after the potentially confounding variables of age, blood pressure, and respiratory frequency were controlled for. Comparison of groups with high and low anxiety (on the basis of a median split of state anxiety scores) showed that BRS was reduced by approximately 20% in the patients with the higher anxiety scores (4.7 +/- 3.2 ms/mm Hg vs 5.7 +/- 3.3 ms/mm Hg, P <.05), after adjustment for differences in age, blood pressure, and respiratory frequency.
Conclusions: High levels of anxiety, but not depression, are associated with reduced vagal control in patients after AMI.