Autonomic Afferent Dysregulation in Atrial Fibrillation

Area of Science:

• Cardiology
• Autonomic Nervous System Function
• Electrophysiology

Background:

• Efferent autonomic tone is not linked to atrial remodeling or AF persistence.
• The specific role of cardiac afferent pathways in AF remains largely unknown.

Purpose of the Study:

• To investigate the function of cardiac afferent reflexes in patients with atrial fibrillation (AF).
• To determine if these reflexes are altered during sinus rhythm (SR) and AF.
• To explore the potential contribution of afferent reflex dysfunction to AF progression.

Main Methods:

• Prospective study of 48 individuals with nonpermanent AF (23 in-AF, 25 in SR) and 12 controls.
• Utilized low-level lower body negative pressure (LBNP) to assess cardiac volume-sensitive reflexes.
• Incorporated Valsalva and isometric handgrip maneuvers to evaluate baroreceptor function.
• Measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR).
• Assessed reversibility of reflex function after tragus stimulation and cardioversion.

Main Results:

• LBNP-induced vasoconstriction was attenuated in SR and dysfunctional in AF patients compared to controls.
• MAP decreased in the in-AF group during LBNP, with unchanged HR.
• Handgrip MAP response was lowest in the in-AF group.
• Tragus stimulation and cardioversion partially improved LBNP vasoconstriction response.

Conclusions:

• Cardiac afferent (volume-sensitive) reflexes are abnormal in AF patients during SR and dysfunctional during AF.
• This dysfunction may play a role in the progression of AF, potentially explaining the "AF begets AF" cycle.