June 26, 2026
View Full PaperLeft atrial thrombus associated with ablation for atrial fibrillation: identification with intracardiac echocardiography
Key Result
Left atrial thrombus was observed in 10.3% of patients during atrial fibrillation ablation despite anticoagulation, with spontaneous echo contrast being the strongest predictor (P<0.0001).
Key Points
- This research aims to investigate the incidence, risk factors, and management of left atrial thrombus detected by intracardiac echocardiography during af ablation.
- Performed intracardiac echocardiography in 232 patients with atrial fibrillation undergoing pulmonary vein ostial ablation.
- Monitored anticoagulation levels following dual transseptal catheterization.
- Analyzed thrombus characteristics and patient history for correlations.
- Left atrial thrombus was observed in 24 out of 232 patients (10.3%), with thrombi measuring an average of 12.9 mm in length and 2.2 mm in width.
- Patients with left atrial thrombus had larger left atrial diameters (4.8 cm vs. 4.5 cm, p < 0.02) and a higher incidence of spontaneous echo contrast (67% vs. 3%, p < 0.0001).
- Multivariate analysis indicated spontaneous echo contrast as a strong predictor of thrombus formation (f = 97.9, p < 0.0001) with no recorded thromboembolic complications.
Study Design
Type
Observational (n=232)
Structured PICO
P
Population
232 patients (average age 55 years, 20.7% female) with atrial fibrillation undergoing pulmonary vein ostial ablation.
E
Exposure
Intracardiac echocardiography (ICE) imaging during left atrial ablation with maintained anticoagulation (activated clotting time >250 s)
O
Outcome
Incidence of left atrial thrombus documented by intracardiac echocardiographysafety
Left atrial thrombus occurs in approximately 10% of patients during AF ablation despite aggressive anticoagulation, is strongly predicted by spontaneous echo contrast, and can be safely managed using ICE guidance.
Abstract
OBJECTIVES: This study reports the incidence of, risk factors for, and management of left atrial (LA) thrombus documented by intracardiac echocardiography (ICE) during LA ablation for atrial fibrillation (AF). BACKGROUND: Thrombus formation is a risk associated with LA ablation procedures. METHODS: Intracardiac echocardiography imaging was performed in 232 patients (184 men, average age 55 +/- 11 years) with AF undergoing pulmonary vein ostial ablation. RESULTS: Anticoagulation (activated clotting time >250 s) was maintained after dual transseptal catheterization. Left atrial thrombus (n = 30) was observed in 24 of 232 patients (10.3%). Thrombi measured 12.9 +/- 11.1 mm (length) and 2.2 +/- 1.3 mm (width) and were attached to a sheath or mapping catheter. Most thrombi (27 of 30, 90%) were eliminated from the LA by withdrawal of the sheath and catheter into the right atrium (RA). Two thrombi became wedged in the interatrial septum and incompletely withdrawn into the RA, and one was recognized only on post-procedure review of ICE images. Patients with LA thrombus had an increased LA diameter (4.8 +/- 0.5 vs. 4.5 +/- 0.6 cm, p < 0.02), spontaneous echo contrast (67% vs. 3%, p < 0.0001) and a history of persistent AF (29% vs. 6%, p < 0.0002). Multivariate discriminant analysis showed that spontaneous echo contrast (f = 97.9, p < 0.0001) was the most important determinant of LA thrombus formation. No patient with LA thrombus suffered a clinical thromboembolic complication. CONCLUSIONS: Left atrial thrombus identified on ICE may occur during LA catheter ablation procedures despite aggressive anticoagulation. Spontaneous echo contrast may predict risk for LA thrombus formation. Left atrial thrombus may be successfully withdrawn into the RA under ICE imaging with no overt complications.