# Evaluation of bi-atrial dynamic electrophysiological properties in atrial septal defect patients

## TL;DR

This study examines how atrial septal defects affect electrical activity in the heart, finding changes in conduction and repolarization in ASD patients.

## Contribution

The study reveals that ASD patients show greater rate adaptation in conduction and repolarization compared to AF patients.

## Key findings

- ASD patients have lower bipolar voltage in both atria compared to controls.
- Conduction and repolarization restitution properties are more pronounced in ASD patients than in AF patients.
- Global conduction velocity is similar between ASD and control patients.

## Abstract

Atrial septal defects (ASD) are associated with an increased incidence of atrial arrhythmias, but their electrophysiological consequences are poorly defined. We hypothesised that conduction and repolarisation would be preferentially altered in the right atrium of ASD patients.

To quantify atrial conduction and repolarisation in ASD patients and determine the impact of structural remodelling on restitution properties.

Patients with an ASD (n = 22) underwent bi-atrial electroanatomic mapping and quantification of effective refractory periods, longitudinal and transverse local conduction. The control group comprised 24 patients without an ASD undergoing ablation for paroxysmal AF.

Bipolar voltage was significantly lower in ASD patients (right atrium: 1.53 ± 0.46 mV versus 1.98 ± 0.59 mV, P = 0.017; left atrium: 1.71 ± 0.36 mV versus 2.06 ± 0.63 mV, P = 0.039). There was no significant difference in global conduction velocity in either atrium between ASD and control patients. Effective refractory periods at 600 ms were not significantly different between patient groups (right atrium: 247 ± 34.7 ms versus 224 ± 36.5 ms, P = 0.071; left atrium: 244 ± 23.9 ms versus 232 ± 40.4 ms, P = 0.29). However, both conduction and repolarisation demonstrated greater rate adaptation in ASD patients in both atria.

Right atrial remodelling, characterised by atrial dilatation and increased low voltage, is present in ASD patients. During fixed rate pacing, conduction and repolarisation properties are similar between ASD and AF patients. However, the restitution properties of both conduction and repolarisation are more pronounced in ASD than AF patients.