Background: The impact of device closure using an Amplatzer Septal Occluder (ASO) on atrial function in patients with atrial septal defect (ASD) remains unknown. This study aimed to clarify the short- and mid-term changes of left atrial (LA) and right atrial (RA) function after ASO implantation.

Methods: Forty-five patients with secundum-type ASD (30 treated by ASO and 15 treated by surgical closure [SC]) and 15 normal children (NC) as controls were investigated. The maximum (Max) and minimum (Min) areas of both atria were measured from the apical four-chamber view via transthoracic echocardiography, and atrial distensibility (Dis) was calculated as (Max−Min)/Min. The ASO group was further divided into two groups based on the ratio of device length to total atrial septal length (D/L) as follows: L-ASO (＞0.85) and S-ASO (＜0.85).

Results: LA Dis was significantly reduced in the ASO (1.10±0.22) and SC groups (1.0±0.44) compared to that in the NC group (1.51±0.25) (p＜0.001), and the rate of reduction was related to D/L in the ASO group. RA Dis was also lower in the ASO (0.87±0.27) and SC groups (0.59±0.24) than in the NC group (1.38±0.37), but the difference was not related to D/L. Max for both atria was similar between the ASO and NC groups whereas Min was elevated for both atria in the ASO group.

Conclusion: Dis declined with D/L in both atria in the ASO and SC groups, and longer follow-up of atrial functions is needed to clarify the potential risk of atrial arrhythmia or dysfunction.