Anatomically determined functional conduction delay in the posterior left atrium relationship to structural heart...

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Surgery

Background:

• The posterior left atrium (PLA) is implicated in initiating and sustaining atrial fibrillation.
• Structural heart disease can alter atrial electrophysiology.

Purpose of the Study:

• To characterize posterior left atrial (PLA) conduction properties in patients with various structural heart diseases.
• To investigate the impact of left ventricular dysfunction, mitral regurgitation, and aortic stenosis on PLA conduction.

Main Methods:

• Epicardial mapping of the PLA was conducted in 34 patients undergoing cardiac surgery.
• Patients were grouped by left ventricular function and valvular disease severity.
• Conduction properties including velocity, heterogeneity, anisotropy, and total activation time were assessed during sinus rhythm and pacing.

Main Results:

• Left atrial size was significantly larger in patients with severe LV dysfunction/CABG and severe MR compared to controls.
• A consistent line of conduction delay was observed in the PLA, more pronounced in patients with LV dysfunction/MR.
• Increased conduction heterogeneity, anisotropy, and total activation time were noted in patients with severe LV dysfunction/MR, leading to circuitous wavefront propagation.

Conclusions:

• A consistent anatomical site of functional conduction delay exists in the posterior left atrium of patients with structural heart disease.
• This delay is most pronounced in conditions with significant atrial enlargement.
• The findings suggest a role for this conduction abnormality in arrhythmogenesis, particularly atrial fibrillation.