title: Complex left atrial appendage morphology and left atrial appendage thrombus formation in patients with atrial fibrillation.
abstract: BACKGROUND
  In patients with atrial fibrillation (AF), most thrombus forms in the left atrial appendage (LAA). However, the relation of LAA morphology with LAA thrombus is unknown.
  
  
  RESULTS
  We prospectively enrolled 633 consecutive patients who were candidates for catheter ablation for symptomatic drug-resistant AF. Transesophageal echocardiography (TEE) was performed to assess LAA thrombus. LAA structure was assessed by 3-dimensional TEE. LAA orifice area, depth, volume, and number of lobes were measured on reconstructed 3-dimensional images. Clinical characteristics and echocardiographic measures were compared to determine variables predicting LAA thrombus. Excluded were 69 (10.9%) patients who met the exclusion criteria. Finally, this study comprised 564 patients, of whom LAA thrombus was observed in 36 (6.4%) patients. Multivariate analysis revealed CHADS2 (Congestive heart failure, Hypertension Age>75, Diabetes mellitus and prior Stroke or transient ischemic attack) score (P=0.002), left ventricular ejection fraction (P=0.01), degree of spontaneous echo contrast (P=0.02), left atrial volume (P=0.02), and number of LAA lobes (P<0.001) to be independently associated with thrombus formation. Most patients with LAA thrombus (32/34, 94.4%) had ≥3 LAA lobes, whereas LAA thrombus was observed in only 2 (0.7%) of 296 patients with 1 or 2 lobes. LAA volume significantly decreased in patients maintaining sinus rhythm after catheter ablation (P=0.0009). Number of LAA lobes did not change in any patient.
  
  
  CONCLUSIONS
  Complex LAA morphology characterized by an increased number of LAA lobes was associated with the presence of LAA thrombus independently of clinical risk and blood stasis. This study suggests that LAA morphology might be a congenital risk factor for LAA thrombus formation in patients with AF.
authors: Cardiovascular Division, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors: Masayoshi
authors: M
authors: Yamamoto
authors: Yoshihiro
authors: Y
authors: Seo
authors: Naoto
authors: N
authors: Kawamatsu
authors: Kimi
authors: K
authors: Sato
authors: Akinori
authors: A
authors: Sugano
authors: Tomoko
authors: T
authors: Machino-Ohtsuka
authors: Ryo
authors: R
authors: Kawamura
authors: Hideki
authors: H
authors: Nakajima
authors: Miyako
authors: M
authors: Igarashi
authors: Yukio
authors: Y
authors: Sekiguchi
authors: Tomoko
authors: T
authors: Ishizu
authors: Kazutaka
authors: K
authors: Aonuma
mesh_terms: D020517:Atrial Appendage / Q000000981:diagnostic imaging*; D001281:Atrial Fibrillation / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D017115:Catheter Ablation; D003937:Diagnosis, Differential; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D017548:Echocardiography, Transesophageal / Q000379:methods*; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000601:surgery; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013927:Thrombosis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology
keywords: anticoagulants; atrial appendage; atrial fibrillation; catheter ablation; echocardiography; stroke; thrombosis