The Effects of Valvular Heart Disease on Atrial Conduction During Sinus Rhythm

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Surgery

Background:

• Atrial fibrillation (AF) pathophysiology can differ based on underlying aortic valve (AV) and mitral valve (MV) disease.
• Understanding the specific arrhythmogenic substrates related to these valve conditions is crucial for targeted therapies.

Purpose of the Study:

• To investigate and compare conduction disorders during sinus rhythm in patients undergoing AV or MV surgery.
• To identify the relationship between conduction abnormalities and the presence of AF.

Main Methods:

• High-resolution epicardial mapping was performed in 85 AV and 54 MV surgery patients.
• Conduction delay (CD) and block (CB) were quantified across the entire atrial surface using approximately 1880 unipolar electrograms per patient.
• Correlation analysis was used to link conduction disorders with patient history of AF and demographics.

Main Results:

• Conduction disorders were most pronounced in the superior intercaval area.
• Mitral valve patients exhibited a significantly higher maximal degree of CD in the lateral left atrium compared to aortic valve patients (4.2 vs 2.3%/cm², p=0.001).
• A history of AF strongly correlated with CD/CB at Bachmann's bundle and patient age.

Conclusions:

• While MV disease is associated with more lateral left atrial conduction issues, disturbed conduction at Bachmann's bundle during sinus rhythm is a key indicator of atrial remodeling linked to AF.
• These findings highlight distinct electrophysiological substrates in AF related to different valve pathologies.