Autonomic Nervous System Dysregulation In Implantable Cardioverter Defibrillator Patients With Depression And Anxiety

Background : Autonomic nervous system (ANS) dysregulation increases risk of ventricular arrhythmias in patients with implantable cardioverter defibrillators (ICD). ANS dysregulation is common in depression and anxiety, but the relationship between these psychological factors and ANS dysregulation has not been investigated in ICD patients. Methods : ANS indices reflecting parasympathetic control of heart rate were obtained using heart rate variability (HRV) analyses in 44 ICD patients with documented coronary artery disease (age 62±9 yrs; ejection fraction 35.9±12.7%). Ambulatory 24-hr ECG recordings were used to calculate HRV (rMSSD and pNN50). Depression was assessed using the Beck Depression Inventory (BDI) and anxiety using the Taylor Manifest Anxiety Scale (TMA). Validated cut-off scores were used (depression: BDI≥10; anxiety: TMa≥9), and data were analyzed using Analysis of Variance. Results : ICD patients with depression symptoms (n=12) had significantly lower HRV markers of ANS parasympathetic activity (rMSSD:15.2±5.7 ms vs. 25.0±13.4 ms, p=0.002; pNN50:1.8±2.7% vs. 5.6±5.7%, p=0.006) than patients with low depression symptoms (n=32). High anxiety (n=10) was related to lower rMSSD (p =0.014). Comorbid depression and anxiety was associated with substantial HRV reduction (p<0.001) (Figure ). Conclusion : Depression and anxiety in ICD patients are associated with autonomic nervous system dysregulation (reduced HRV markers of parasympathetic control). Reduced parasympathetic activity may therefore contribute to the elevated risk of life-threatening cardiac arrhythmias in ICD patients with depression and anxiety. Figure 1. RMSSD among depression/anexity groups