Introduction
Catheter ablation is an effective treatment for suppressing atrial fibrillation (AF) and has a high success rate.1, 2 With the recent development of ablation technology and mapping devices and growing indications of catheter ablation in patients with AF, most patients are recurrence-free from AF after the initial catheter ablation procedure. However, the success rate is not absolute, and some patients have a recurrence after the initial ablation. These patients are often scheduled to undergo repeat sessions for recurrent AF when associated with intolerable symptoms and frequent occurrence.
Transesophageal echocardiography (TEE) is the gold standard for evaluating left atrial (LA) thrombi before AF ablation, and a recent expert consensus report recommended the necessity of excluding the possibility of LA thrombi before the initial AF catheter ablation.3 Nonetheless, the relevance of evaluating the presence of thrombi at repeat sessions due to recurrence remains unclear. After the first session, although patients have a recurrence, the burden and duration of AF may significantly decrease, and these patients usually continue oral anticoagulants following the procedure, which could indicate that the thrombi are unlikely to develop in those patients after the first session.4It is unclear whether imaging examination to screen for LA thrombi is necessary at repeat sessions, especially in patients at low risk and in early repeat ablation. Since TEE is associated with the risk of aspiration pneumonia and pharyngeal perforation, although with a very low prevalence, it is important to avoid unnecessary examinations which impose a burden on the patient and cause discomfort before the repeat ablation.
To test this hypothesis, the present study was conducted to assess the occurrence of thrombi at repeat ablation for AF recurrence after the first session and the frequency of any imaging study, including TEE and contrast-enhanced computed tomography (CT) imaging, for thrombi screening before the repeat procedure in a large cohort study. We investigated which factors and time to repeat ablation were associated with safety outcomes regarding thrombi development during AF repeat ablation and with the requirement for invasive imaging studies for evaluating thrombi development.