Atrial Cardiomyopathy and Atrial Fibrillation: Insight From Histopathological Analysis of Atrial Biopsies

Area of Science:

• Cardiology
• Pathology
• Medical Imaging

Background:

• Atrial cardiomyopathy (AC) is a key driver of atrial fibrillation (AF) persistence and poor outcomes.
• The precise histopathological basis of AC in non-valvular AF is unclear due to limited tissue samples.
• Fibrosis has been considered the primary feature, but other changes are likely involved.

Purpose of the Study:

• To investigate the detailed histopathological features of atrial cardiomyopathy in patients with non-valvular AF.
• To assess the utility of intracardiac echocardiography-guided right atrial biopsy combined with electroanatomic mapping for characterizing AC.
• To identify potential early diagnostic markers and understand sex-based differences in AC.

Main Methods:

• An integrated approach using intracardiac echocardiography-guided right atrial biopsy and high-density electroanatomic mapping was employed in AF ablation patients.
• Histopathological analysis of biopsied atrial tissue was performed.
• Atrial voltage reduction was correlated with specific histopathological findings.

Main Results:

• Atrial voltage reduction in AF patients is associated with fibrosis, intercellular space expansion, myofibrillar loss, reduced nuclear density, and cardiomyocyte hypertrophy.
• Atrial biopsy identified atrial amyloidosis in approximately 7% of patients, often at an early stage.
• Women exhibited consistently lower atrial voltage, attributed to smaller myocardial mass rather than increased remodeling.

Conclusions:

• Right atrial biopsy provides patient-specific histopathological assessment of atrial cardiomyopathy, offering deeper mechanistic insights.
• This approach can detect early-stage atrial amyloidosis, suggesting potential for earlier diagnosis and intervention.
• Findings enhance understanding of AC pathophysiology and inform future AF management strategies.