Autonomic modulation impacts conduction velocity dynamics and wavefront propagation in the left atrium

Area of Science:

• Electrophysiology
• Cardiac Pathophysiology
• Medical Imaging

Background:

• Atrial fibrosis and autonomic nervous system remodeling are implicated in the pathophysiology of atrial fibrillation (AF).
• Understanding the impact of these factors on cardiac electrical activity is crucial for developing effective treatments.

Purpose of the Study:

• To evaluate the influence of atrial fibrosis and autonomic modulation on conduction velocity (CV) dynamics and cardiac wavefront propagation.
• To investigate the relationship between local voltage amplitude, CV restitution, and autonomic influences.

Main Methods:

• Local activation times (LATs), voltage, and geometry data were collected from 54 patients undergoing ablation for persistent AF.
• CV dynamics were assessed at three pacing intervals in sinus rhythm.
• The effects of pharmacological (atropine, isoprenaline) and electrical (ganglionated plexi stimulation) autonomic modulation on CV, wavefront propagation, and pivot points were determined.

Main Results:

• CV dynamics were significantly influenced by local voltage amplitude, with steeper CV restitution curves in non-low voltage zones.
• Isoprenaline and ganglionated plexi stimulation led to greater rate-dependent CV slowing and increased CV heterogeneity.
• A high proportion (80.2%) of identified pivot points (significant changes in wavefront propagation) co-located with sites of rate-dependent CV slowing.

Conclusions:

• Atrial CV dynamics are modulated by fibrosis burden, affecting electrical propagation.
• Autonomic modulation significantly enhances atrial CV heterogeneity and alters the distribution of critical pivot points.
• This study offers insights into the role of autonomic remodeling in AF pathophysiology.