Atrial septal defect detected on transesophageal echocardiography prior to atrial fibrillation ablation: prevalence, clinical features, and outcome after ablation

Abstract Background The prevalence rate of atrial septal defect (ASD) in the general population is about 0.09%. Long-term volume overload due to a left-to-right shunt (LRS) caused by ASD commonly results in atrial fibrillation (AF). Moreover, left atrial (LA) enlargement could lead to an increase stretched type patent foramen ovale (PFO) and LRS. However, the prevalence, clinical features, and clinical impact of LRS in AF prior to ablation remain unknown. Methods A total of 2966 AF patients (63 ± 11 years, 782 women) who underwent initial AF ablation were retrospectively enrolled in this study. All patients underwent transesophageal echocardiography (TEE) prior to ablation. Then, they were divided into three groups: the ASD, PFO, and control groups. Large ASD was defined as a defect with a diameter of ≥ 5 mm. Clinical and echocardiographic features and 5-year AF-free survival rate after ablation were compared between each group. Results Based on TEE prior to AF ablation, 40 (1.3%) and 174 (5.9%) patients had ASD and PFO, respectively. Patients with PFO had a high prevalence of persistent AF (P < 0.001). The The LA volume was larger in the ASD and PFO groups than in the control group (P < 0.001). Kaplan–Meier analysis showed that the AF-free survival rate was similar between all ASD groups (49 ± 10%, P = 0.24). Further, the 5-year AF-free survival rate was significantly lower in the large ASD group than in the small (< 5 mm) ASD, PFO, and control groups (28% ± 14%, 61% ± 3%, 59% ± 5%, and 60% ± 1%, respectively; P = 0.021). Cox proportional hazards regression analysis showed that a large ASD was an independent predictor of AF recurrence (odds ratio: 2.58, 95% confidence interval: 1.17−4.85, P = 0.02). Conclusions Patients with AF prior to ablation had a higher prevalence of ASD than the general population. TEE could identify ASD undiagnosed on transthoracic echocardiography. In particular, a large ASD on TEE could be associated with poor outcome after AF ablation.