Impact of interatrial septal thickness and interatrial conduction time on cryoballoon ablation outcome

Interatrial septal thickness (IAST) is an indirect measure of interatrial septal fat which is anatomic extension of epicardial fat. Interatrial conduction time (IACT) reflects altered conduction between atria. Both parameters are associated with left atrial (LA) fibrosis and atrial fibrillation (AF). However, limited data exist regarding the influence of IAST and IACT on the outcomes of cryoballoon ablation (CBA). In this study, we aimed to analyze possible effect of IAST and IACT on atrial tachyarrhythmia (ATA) free survival after CBA.

Sixty five patients (34/65, 52.3% male, 53.3±11.0 years old) undergoing first time CBA for pulmonary vein isolation were enrolled. Pre-procedural TEE images were analyzed and bicaval view was used to visualize SVC rim for IAST measurement (Figure 1). IACT was measured from the onset of surface P wave to atrial EGM recorded by distal coronary sinus electrode. After 3 months blanking period all anti-arrhythmic drugs were discontinued. Clinical endpoint was ATA recurrence including AF, flutter or tachycardia lasting more than 30 seconds. After 11.2±4.1 months of follow-up 8 patients (12.3%) had ATA recurrence. IAST (4.4±1.1 vs 3.3±0.6 mm, p=0.007) and LA volume index (37.4±8.0 vs 30.1±12.4 mL/m2, p=0.03) were greater in patients with ATA recurrence than those without. In contrast, patients with and without had similar IACT (85.8±31.1 vs 62.2±23.9 ms, p=0.10).

Pre-procedural measurement of IAST using TEE may provide prognostic information in CBA patients. Increased IAST was found to be associated with ATA recurrence after CBA based PVI and warrants further study.

Interatrial septal thickness measurement