REN and major depressive disorder: To summarize the conclusions of previous studies, the mechanism of occurrence or recurrence of AF caused by depression may involve the following aspects (16, 17): Anxiety and depression can activate the renin-angiotensin-aldosterone system, play a significant role in promoting cardiac fibrosis, delay atrial conduction and reentry, increase atrial pressure, change atrial electrophysiological remodeling, and thus lead to the occurrence or recurrence of atrial fibrillation.