Background: Depression is associated with increased risk of death among patients with coronary disease. Cardiovascular autonomic dysregulation may be one of the mechanisms by which depression exerts its effects on cardiovascular function. The purpose of this study was to determine whether depressive symptoms are associated with low heart rate variability (HRV) and prolonged HR recovery after exercise testing in patients with coronary artery disease (CAD).
Methods: The Psychophysiological Investigation of Myocardial Ischemia (PIMI) was a large, multicenter study designed to assess psychological and physiological correlates of stress in patients with CAD. One hundred and eighty-eight patients with CAD as evidenced by at least 50% blockage of one major artery and a previous positive exercise stress test were included in this study. Patients included in this report were not taking beta blockers. Cardiovascular functioning was assessed by a modified Bruce protocol treadmill stress test. Measures of psychological functioning, including the Beck Depression Inventory (BDI), were also obtained.
Results: BDI scores were negatively correlated with HR recovery (r = -0.15, p = .04). Depression scores accounted for 3.5% of the variance in HR recovery when controlling for participant age (p < .01). Depressive symptoms were related to two HRV indices (ultra-low frequency, high frequency).
Conclusions: Depressive symptoms are associated with cardiovascular autonomic nervous system dysfunction as assessed by HR recovery. This relationship is not merely due to an association of depression severity with beta blocker usage or a failure of depressed patients to achieve an adequate chronotropic response.