Comparison between intracardiac and transesophageal echocardiography for the detection of thrombus in the left atrial appendage in relation to in-hospital and one-year outcome among patients undergoing atrial fibrillation ablation

BACKGROUND: Transesophageal echocardiography (TEE) is the standard method for excluding left atrial appendage (LAA) thrombus before atrial fibrillation (AF) ablation. Intracardiac echocardiography (ICE), used during ablation, allows LAA assessment at the procedure's beginning. Preliminary data suggest that ICE may provide thrombus visualization, but evidence remains limited. AIMS: To compare ICE and TEE for LAA thrombus detection and procedural outcomes in AF ablation. METHODS: This retrospective cohort study included 610 adults undergoing catheter ablation for AF or atrial flutter between 2017 and 2024. Patients treated in the period 2017-2020 underwent preprocedural TEE (n = 289), while those in 2020-2024 underwent ICE (n = 321) for LAA assessment during the ablation. All patients received uninterrupted anticoagulation, predominantly direct oral anticoagulants (86.5% vs. 92.2%; P = 0.02). The primary outcome was LAA thrombus detection. Secondary outcomes included procedure duration, in-hospital complications, hospitalization length, acute procedural success, and AF recurrence at 3 and 12 months. RESULTS: Baseline characteristics were comparable, although patients in the ICE group had higher HAS-BLED scores and longer AF duration. Radiofrequency ablation was more frequent in the ICE group, while cryoballoon ablation predominated in the TEE group (P <0.001). LAA thrombus was detected in 1% of TEE patients and in none of the ICE patients (P = 0.11). Complication rates were low and similar between groups. Hospital stay was shorter in the ICE group, whereas procedural success, procedure time, and AF recurrence did not differ. CONCLUSIONS: ICE may allow for LAA thrombus detection comparable to TEE with similar safety outcomes.