Left atrial volume index as a factor of early filling defects in the left atrial appendage: insights from optimized cardiac computed tomography imaging in atrial fibrillation.

OBJECTIVES

Early filling defects in the left atrial appendage (LAA), observed during the early phase of cardiac computed tomography (CT), are associated with increased risks of stroke and cardiovascular events. This study aims to evaluate the relationships between left atrial volume (LAV), left atrial appendage volume (LAAV), and the LAA orifice area, as well as identify factors associated with early LAA filling defects in atrial fibrillation (AF) patients, using optimized cardiac phases in multiphase CT imaging.

MATERIALS AND METHODS

This retrospective study analyzed 562 patients with AF who underwent cardiac CT before pulmonary vein isolation (PVI). Relationships between LAV, LAAV, and LAA orifice area were assessed using Pearson's rank correlation coefficients. Factors associated with early LAA filling defects were evaluated using multivariate logistic regression. Receiver operating characteristic analysis was performed to determine the threshold value predictive of these defects. The impact of PVI on defect resolution was also assessed.

RESULTS

Left atrial volume index (LAVI) was significantly correlated with LAAV index (ρ = 0.59, p < 0.001) and LAA orifice area index (ρ = 0.66, p < 0.001). Maximum LAVI was independently associated with early LAA filling defects (p < 0.001), with a threshold of 78.5 cm³/m² yielding 81.9% sensitivity and 77.6% specificity. Among 49 patients with initial defects, 27 underwent follow-up CT after PVI, and 88.9% showed resolution accompanied by significant LAV reductions.

CONCLUSION

The maximum LAVI is a critical factor associated with LAA early filling defects, with reductions in LAV after PVI leading to defect resolution.

KEY POINTS

Question What factors are associated with early left atrial appendage (LAA) filling defects, and do these defects resolve following pulmonary vein isolation (PVI)? Findings A left atrial volume index (LAVI) threshold of 78.5 cm³/m² is associated with early LAA filling defects, which resolve after PVI-induced reductions in LAVI. Clinical relevance Identifying the association between LAVI and early LAA filling defects may improve risk stratification for cardiovascular and thromboembolic events in patients with atrial fibrillation. PVI-induced reductions in LAVI could contribute to a decrease in the risk of such events.