Abstract

There is evidence linking mood disorders (MDs) and anxiety disorders (ADs) to coronary artery disease (CAD) risk, morbidity and mortality. However, research on the mechanisms mediating this association is immature. Mental stress-induced myocardial ischemia and reduced heart rate variability (HRV) (a marker of autonomic nervous system (ANS) dysregulation) are two mechanisms proposed to link MDs and ADs to CAD risk. The aim of this study was to evaluate (1) the frequency, duration and triggers of myocardial ischemia during daily life in CAD patients with comorbid MDs and ADs; (2) HRV in panic disorder (PD) patients with established CAD; and (3) the relationship between Hi versus Lo anxiety sensitivity (AS) and HRV in patients with CAD. Seventy-one patients (n = 28 with primary AD (n = 20 with PD); n = 20 with primary MD; n = 23 controls) with exercise ischemia underwent 48-hour Holter monitoring to evaluate ST-segment depressions (ischemia) and HRV (time and frequency domain indices). Patients completed a diary and the Anxiety Sensitivity Index (ASI), Beck Depression Inventory (BDI), State-Trait Anxiety and Anger Inventories (STAI-STAXI), and the Cook-Medley Hostility Inventory (CMHO). All patients were maintained on cardiac medication. Chi-squares and ANCOVAs were conducted for nominal and continuous variables respectively; frequency domain indices of HRV were assessed via spectral analysis. A total of 21 ischemic episodes were recorded for 6 patients. Because so few patients had ischemia results were not significant. While 2/21 ischemic episodes occurred in controls (mean = 1; mean duration = 20 min) 19 episodes occurred in AD patients (mean = 4.75; mean duration = 127 min). Diaries indicated that 42% of episodes in AD patients (versus none in controls) were preceded by mental stress (negative emotions). Interestingly, more MD patients (70%) reported having at least 1 episode of chest pain during the 48-hour period compared to AD patients (50%) and controls (30%) (p < 0.05). MD patients also reported having more episodes of chest pain (4.45) compared to AD patients (1.75) and controls (0.87) (p < 0.05). HRV analyses showed that after controlling for important confounders, PD patients with CAD exhibited significantly lower LF:HF ratios compared to controls (p < 0.05), and HiAS patients exhibited significantly lower LF, VLF and ULF power relative to LoAS patients (p's < 0.05). Interestingly, HRV was not related to BDI, STAI, STAXI or CMHO scores. Findings suggest that CAD patients with a MD reported more chest pain (without evidence of ischemia) but those with an AD demonstrated more (though not significantly) mental stress-induced ischemia relative to patients with a MD or no psychiatric diagnosis. Findings also suggest that PD patients with CAD show dominant parasympathetic tone under baseline (ordinary daily life) conditions that may reflect a dysregulation of ANS functioning. Finally, results show that high AS is associated with reduced HRV suggesting an association between high AS and dysregulated cardiac autonomic tone.