Correlation between left atrial appendage morphology and flow velocity in patients with paroxysmal atrial fibrillation

Reduction of left atrial appendage (LAA) flow velocity (FV) is a risk factor for thrombus formation and increases the risk of stroke in patients with atrial fibrillation (AF). Furthermore, LAA morphology is correlated with stroke in patients with AF. The aim of this study was to correlate LAAFV with LAA morphology in patients with AF. We studied 96 patients (age 59.0 ± 10.2 years, 75% male) referred for radiofrequency catheter ablation for paroxysmal AF. All patients underwent computed tomography (CT) and transthoracic and transoesophageal echocardiography during sinus rhythm. LAA morphology was classified as one of the four types (chicken wing, windsock, cactus, and cauliflower) on CT images. There were significant differences in LAAFV among LAA morphologies (chicken wing 73.7 ± 21.9 cm/s, windsock 61.9 ± 19.6 cm/s, cactus 55.3 ± 14.1 cm/s, cauliflower 52.7 ± 18.1 cm/s, P = 0.008). Post hoc multiple comparisons showed that LAAFV was higher in patients with chicken wing than in those with cactus (P = 0.006, vs. chicken wing) and cauliflower (P = 0.006, vs. chicken wing), but not with windsock (P = 0.102). After adjustment for clinical and LAA anatomical covariates (orifice area, volume, and trabeculation), multiple linear regression analyses revealed that LAA morphology was an independent determinant of LAAFV [chickens wing: standardized partial regression coefficients (β) = 0.317, P = 0.0014; windsock: β = 0.303, P = 0.038]. LAA morphology is a significant determinant of LAAFV, suggesting an underlying mechanism for the association between LAA morphology and embolic events.