Left atrial appendage morphologic pattern determined by computed tomography is a new predictor of high risk patient for embolism with atrial fibrillation

Assessing thromboembolic risk is crucial for proper management of patients with atrial fibrillation. Left atrial volume is a promising predictor of cardiac thrombosis. To determine whether left atrial volume can predict left atrial appendage thrombus in patients with atrial fibrillation, we conducted a prospective study of 73 patients. Left atrial and ventricular volumes were evaluated by cardiac computed tomography with retrospective electrocardiographic gating and then indexed to body surface area. Left atrial appendage thrombus was confirmed or excluded by cardiac computed tomography with delayed enhancement. Seven patients (9.6%) had left atrial appendage thrombus; 66 (90.4%) did not. Those with thrombus had a significantly higher mean left atrial end-systolic volume index (139 ± 55 vs 101 ± 35 mL/m2; P =0.0097) and mean left atrial end-diastolic volume index (122 ± 45 vs 84 ± 34 mL/m2; P =0.0077). On multivariate logistic regression analysis, left atrial end-systolic volume index (per 10 mL/m2 increase) was significantly associated with left atrial appendage thrombus (odds ratio [OR]=1.24; 95% CI, 1.03–1.50; P =0.02); so too was the left atrial end-diastolic volume index (per 10 mL/m2 increase) (OR=1.29; 95% CI, 1.05–1.60; P =0.02). These findings suggest that increased left atrial volume increases the risk of left atrial appendage thrombus. Therefore, patients with atrial fibrillation and an enlarged left atrium should be considered for cardiac computed tomography with delayed enhancement to confirm whether thrombus is present.

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Abstract 14676: Landmark-based Functional Computed Tomography Reveals Diminished Left Atrial Appendage Contraction During Atrial Fibrillation

Circulation ◽

10.1161/circ.142.suppl_3.14676 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Jonathan H Chung ◽

Gordon Ho ◽

Andrew Schluchter ◽

Francisco Contijoch ◽

Jonathan C Hsu ◽

...

Keyword(s):

Computed Tomography ◽

Atrial Fibrillation ◽

Ejection Fraction ◽

Sinus Rhythm ◽

Ct Scan ◽

Blood Volume ◽

Left Atrial ◽

Left Atrial Appendage ◽

Atrial Appendage ◽

History Of

Introduction: The formation of thrombus in the left atrial appendage (LAA) and risk for systemic embolization may result in part from stasis and poor blood volume emptying during atrial fibrillation (AF). Functional 4-dimensional computed tomography (4DCT) is a promising technique to measure LAA ejection fraction and blood volume emptying. Hypothesis: We hypothesize that the LAA ejection fraction measured by 4DCT is decreased during AF compared to sinus rhythm. Methods: 256-slice 4DCT scans obtained in patients for coronary artery imaging or pre-procedurally for AF, VT or SVT ablation procedures were analyzed retrospectively. In each patient, LAA volumes were measured at multiple phases during one cardiac cycle using segmentation software (ITK-SNAP and Osirix MD). LAA ejection fraction was calculated as the difference between minimum and maximum volumes and was analyzed using Wilcoxon rank sum. Results: Out of 54 patients, 37 patients were in sinus rhythm and 17 patients were in AF. Between NSR vs. AF, mean age was 69.1±12.8 vs 73.2±11.5 years (p=0.13), 28% vs 36% female (p=0.54), LVEF was 58±11% vs 60±9% (p=0.95), and echo-derived left atrial volume index was 29.5±6.1 ml/m2 vs 41.7±12.8 ml/m2 (p=0.06). Patients who were in sinus rhythm during their CT scan had a higher LAA ejection fraction than those who were in AF (58±13% vs. 29±9%, p<0.0001). For patients who were in AF during their CT scan, there was no difference in LAA ejection fraction between patients with a history of paroxysmal AF compared to patients with a history of persistent AF (30±10% vs. 28±10%, p=0.75). Conclusions: Analysis of the LAA volumes using functional cardiac CT is a feasible method to quantify blood volume emptying from the LAA. Patients in AF were observed to have significantly decreased LAA ejection fraction and blood volume emptying compared to patients in sinus rhythm. Further studies are needed to determine whether this technique may improve personalized risk stratification for stroke.

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