Chamber-specific wall thickness features in human atrial fibrillation.

Area of Science:

• Cardiovascular Research
• Medical Imaging
• Electrophysiology

Background:

• Persistent atrial fibrillation (AF) treatment is limited by the lack of tools to identify patient-specific AF substrates.
• Localized drivers in both the right atrium (RA) and left atrium (LA) maintain persistent AF in 30-50% of patients.
• Chamber-specific atrial wall thickness (AWT) features underlying AF drivers remain poorly understood despite AWT's known role.

Purpose of the Study:

• To provide direct evidence of distinct RA and LA AWT features associated with AF drivers.
• To analyze chamber-specific AWT characteristics in human atria ex vivo using advanced imaging and mapping techniques.

Main Methods:

• Coronary-perfused human atria (n=7) underwent pacing-induced AF and panoramic near-infrared optical mapping.
• High-resolution (170 µm³) 9.4 T gadolinium-enhanced MRI was used for structural imaging.
• 3D AWT was segmented and analyzed throughout the atrial chambers, correlating with identified AF driver locations.

Main Results:

• Optical mapping identified localized RA drivers (n=4 hearts) and LA drivers (n=3 hearts).
• RA with drivers showed thicker AWT and greater AWT variation compared to RA without drivers (p < 0.05). RA driver regions were significantly thicker and more variable (p < 0.05).
• LA with drivers was thinner than LA without drivers. LA driver regions were significantly thinner than other LA regions (p < 0.05).

Conclusions:

• This study demonstrates chamber-specific AWT features differentiating AF driver regions in RA and LA.
• Right atrial driver regions exhibit increased thickness and AWT variability, contrasting with thinner left atrial driver regions.
• Patient-specific evaluation of AWT should be considered for developing chamber-specific, targeted ablation strategies for persistent AF.