Cardiac rhythm disturbances in patients with left atrial isomerism

Area of Science:

• Cardiology
• Pediatric Cardiology
• Electrophysiology

Background:

• Left atrial isomerism (LAI) is a complex congenital heart defect associated with significant cardiac anomalies.
• Sinus node and atrioventricular (AV) conduction tissue abnormalities are frequently observed in LAI patients.
• Understanding the long-term implications of these conduction defects is crucial for patient management.

Purpose of the Study:

• To investigate the clinical significance of defective sinus node and AV conduction tissue in patients with left atrial isomerism (LAI).
• To characterize the incidence and types of bradyarrhythmias and other conduction abnormalities in this patient population.
• To assess the impact of these arrhythmias on long-term outcomes.

Main Methods:

• Long-term retrospective study of 22 patients diagnosed with LAI between 1984 and 1998.
• Analysis of patient demographics, associated cardiac anomalies, palliative interventions, and electrophysiological findings.
• Detailed assessment of bradyarrhythmia development, including type, onset, and relationship to surgical procedures.

Main Results:

• Over half of the LAI patients (64%) developed bradyarrhythmia, primarily junctional rhythm and sinus bradycardia, with a median onset at 78 months.
• The probability of remaining free from bradyarrhythmia was 80% at 2 years and 46% at 6 years.
• Junctional ectopic tachycardia occurred post-Fontan-type operation in 3/6 patients, and Mahaim-like pathways were identified in 2 patients.

Conclusions:

• Patients with LAI exhibit a high propensity for developing bradyarrhythmias due to inherent sinus node dysfunction.
• AV conduction abnormalities, including compromised conduction, post-operative junctional ectopic tachycardia, and Mahaim-like pathways, are significant concerns in LAI.
• Proactive electrophysiological monitoring and management are essential for patients with left atrial isomerism.