Complex left atrial appendage morphology and left atrial appendage thrombus formation in patients with atrial fibrillation.
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.


METHODS AND 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.
['Yamamoto|Masayoshi|M|', 'Seo|Yoshihiro|Y|', 'Kawamatsu|Naoto|N|', 'Sato|Kimi|K|', 'Sugano|Akinori|A|', 'Machino-Ohtsuka|Tomoko|T|', 'Kawamura|Ryo|R|', 'Nakajima|Hideki|H|', 'Igarashi|Miyako|M|', 'Sekiguchi|Yukio|Y|', 'Ishizu|Tomoko|T|', 'Aonuma|Kazutaka|K|']
D020517:Atrial Appendage D001281:Atrial Fibrillation D017115:Catheter Ablation D003937:Diagnosis, Differential D019560:Echocardiography, Three-Dimensional D017548:Echocardiography, Transesophageal D005500:Follow-Up Studies D006329:Heart Conduction System D006331:Heart Diseases D006801:Humans D015994:Incidence D007564:Japan D008297:Male D008875:Middle Aged D011379:Prognosis D011446:Prospective Studies D015203:Reproducibility of Results D018570:Risk Assessment D012307:Risk Factors D015996:Survival Rate D013927:Thrombosis
atrial appendage atrial fibrillation catheter ablation echocardiography stroke anticoagulants thrombosis