Factors associated with left atrial appendage filling defects on early-phase cardiac computed tomography in patients with nonvalvular atrial fibrillation: a case-control study

The significance of left atrial appendage (LAA) filling defects on early-phase cardiac computed tomography (CCT) remains uncertain. This study retrospectively investigated predictive factors of LAA filling defects on early-phase CCT.

A total of 68 patients with nonvalvular atrial fibrillation (AF) and early filling defect on CCT who underwent transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were enrolled [48 males, 20 females; mean ± standard deviation (SD) age 62.72±8.13 years]. Additionally 68 sex- and age-matched patients with normal LAA filling were included as the control group. CCT, ultrasound, clinical and laboratory data were analyzed. Baseline data between groups were analyzed using t-, Mann-Whitney, and chi-squared tests. Multivariable logistic regression analysis was used to adjust for confounders. Pearson correlation analysis was used to confirm correlations between variables.

Decreased LAA flow velocity [LAAFV; odds ratio (OR) =0.918; 95% confidence interval (CI): 0.883-0.954; P<0.001] and increased left atrial volume index (LAVI; OR =1.055; 95% CI: 1.012-1.099; P=0.011) were significantly associated with early-phase CCT LAA filling defects. The LAAFV threshold for predicting early LAA filling defects was 40.5 cm/s, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.905 (sensitivity 82.4%, specificity 91.2%); the LAVI predictive threshold was 58.77 mL/m² (AUC =0.840, sensitivity 85.3%, specificity 72.1%). A significant positive correlation was detected between LAAFV and the Hounsfield unit (HU) ratio of the LAA to ascending aorta on early-phase CCT (r=0.614; P<0.001), as well as the HU difference in LAA between early and delayed phase CCT (r=0.591; P<0.001). There were significant (P<0.05) differences in LAAFV between different filling defects.

Decreased LAAFV and increased LAVI are independent factors associated with LAA filling defects only on early-phase CCT. Early-phase CCT LAA filling defect is associated with LAA emptying dysfunction. These findings contribute to thrombosis risk stratification in patients with AF.