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Incidence and predictors of left atrial thrombus development in patients scheduled for repeat catheter ablation for atrial fibrillation: Is transesophageal echocardiography always mandatory?

Introduction: The risk of developing left atrial (LA) thrombi after
initial catheter ablation for atrial fibrillation (AF) and requirements
for imaging evaluation for thrombi screening at repeat ablation is
unclear. This study aimed to assess the occurrence of thrombus
development and frequency of any imaging study evaluating thrombus
formation during repeat ablation for AF. Methods: Of 2,066 patients
undergoing initial catheter ablation for AF with uninterrupted oral
anticoagulation, 615 patients underwent repeat ablation after 258.0
(105.0-882.0) days. We investigated which factors were associated with
safety outcomes and requirements for thrombi screening. Results: All
patients underwent at least one imaging examination to screen for
thrombi in the first session, but the examination rate decreased to 476
patients (77%) before the repeat procedure. The frequency of imaging
evaluations was 5.0%, 11%, 21%, 84%, and 91% for transesophageal
echocardiography and 18%, 33%, 49%, 98%, and 99% for any imaging
modality at repeat ablation performed ≤60 days, ≤90 days, ≤180 days,
>180 days, and >1 year after the initial
procedure, respectively. Three patients (0.5%) developed LA thrombi at
repeat ablation due to identifiable causes, and no patients had
thromboembolic events when no imaging evaluation was performed.
Multivariate analysis revealed that repeat ablation >180
days, non-paroxysmal atrial arrhythmias, and lower left ventricular
ejection fraction were predictors of the risk of thrombus development.
Conclusions: The risk development of thrombus at repeat ablation for AF
was low. There needs to be a risk stratification for the requirement of
imaging screening for thrombi at repeat ablation for AF.