1. Study Purpose The primary aim of this research was to systematically describe and characterize a novel, thrombus-mimicking artifact observed during Intracardiac Echocardiography (ICE), termed the "Floating Lotus" sign. The study sought to define its imaging features, determine its prevalence, and identify the clinical factors that predict its occurrence. This was driven by the clinical need to prevent the misdiagnosis of this pseudo-thrombus as a true Left Atrial Appendage (LAA) thrombus, which could lead to unnecessary procedure cancellations or anticoagulation changes.
2. Study Population The study population consisted of 172 consecutive patients with non-valvular atrial fibrillation (AF) who underwent ICE-guided catheter ablation and/or left atrial appendage occlusion (LAAO) between January and December 2024 across three tertiary medical centers. Patients with confirmed intracardiac thrombus, significant valvular heart disease, or prior cardiac surgery were excluded.
3. Key Research Focus

The key research focus was a multi-faceted investigation of the "Floating Lotus" sign:

Incidence and Imaging Characterization: To quantify how common this sign is (found in 27.9% of patients) and meticulously describe its dynamic sonographic appearance-a mobile, echogenic mass within an anechoic space (pericardial effusion) that merges with the LAA wall upon catheter rotation.

Identification of Clinical Predictors: To analyze which patient factors are associated with the sign. The study identified heart failure (LVEF <55%) as the sole independent predictor through multivariable analysis.

Clinical Correlation and Differentiation: To examine the sign's association with other clinical parameters (e.g., recent stroke, larger left atrial diameter) and emphasize the critical imaging maneuver (catheter rotation) that differentiates it from a true LAA thrombus, thereby highlighting its direct implications for procedural safety and decision-making.

Inclusion Criteria:

• Patients with a confirmed diagnosis of non-valvular atrial fibrillation (paroxysmal or persistent).
• Completion of complete intracardiac echocardiography (ICE) imaging during the catheter ablation or left atrial appendage occlusion (LAAO) procedure.

Exclusion Criteria:

• Confirmed intracardiac thrombus on pre-procedural transesophageal echocardiography (TEE) or left atrial computed tomography angiography (CTA).
• Significant valvular heart disease (moderate or severe stenosis/regurgitation) or a history of cardiac surgery.
• Incomplete clinical or imaging data.

The study population was derived from patients with atrial fibrillation who consecutively underwent intracardiac echocardiography (ICE)-guided catheter ablation and/or left atrial appendage occlusion (LAAO) between January and December 2024 at three tertiary medical centers in China.

We plan to share fully de-identified individual participant data (IPD) that underlie the results reported in the primary publication of this study. This includes:

Baseline demographic and clinical characteristics; Procedural echocardiographic parameters ; These data will be made available upon reasonable request to researchers whose proposed use has been approved by an independent review committee for legitimate scientific purposes. Data will be shared after the publication of the primary results, typically within 12 months. Data access requires a signed data use agreement to ensure compliance with ethical and privacy regulations.

Available starting 12 months after publication of the primary results, for a duration of 12 months.

Access granted only to qualified researchers upon reasonable request. Only de identified participant-leveldata will be shared. Requests are subject to sponsor approval.