3f - HEART-BRAIN AXIS: DEPRESSION & ARRHYTMIA

Question 1

Core concept

Answer 1

• Heart-brain axis = bi-directional communication system involving neurological, endocrine, autonomic &
  inflammatory pathways
• Depression & arrhythmia share common pathophysiological network, where psychological distress affects
  cardiac electrophysiology & opposite
• Link helps explain why depression = independent risk factor for cardiac arrhythmias, especially atrial
  fibrillation (AF) & ventricular arrhythmias

Question 2

Mechanisms linking depression & arrhythmia

Answer 2

Table

Question 3

Clinical evidence for heart-brain link

Answer 3

CLINICAL EVIDENCE FOR HEART–BRAIN LINK
- Depression doubles risk of developing arrhythmia, particularly AF
- Arrhythmias more frequent in patients with history of major depressive disorder (MDD), post-MI depression & stress-related disorders
- Heart rate variability (HRV) = non-invasive marker of vagal tone, significantly reduced in depressed
individual, predictive of arrhythmia risk

Question 4

Inflammation as common pathway

Answer 4

• Both depression & arrhythmia involve chronic low-grade inflammation
• Inflammatory cytokines like IL-1β, IL-6, and TNF-α:
  o Influence mood via hypothalamus and limbic system.
  o Promote atrial fibrosis & structural remodeling, increasing AF risk

Question 5

Brain areas implicated

Answer 5

• Prefrontal cortex, anterior cingulate cortex, insula, & amygdala:
  o Regulate autonomic function & emotional response
  o Dysfunction here leads to cardiac autonomic imbalance & emotional dysregulation

Question 6

Clinical implications:
- psychiatric management of cardiac patients
- therapeutic strategies

Answer 6

Psychiatric Management of Cardiac Patients
- Depression screening in patients with arrhythmia (especially AF & post-MI)
- Use of validated tools like PHQ-9 or HADS in cardiology settings

Therapeutic Strategies
- Beta-blockers & SSRIs/SNRIs may improve both mood & arrhythmia outcomes
- Mindfulness, psychotherapy & vagal nerve stimulation (VNS): promising non-pharmacological options
- Caution: Some antidepressants (ex: tricyclics) can prolong QT interval & increase arrhythmia risk