Left atrial appendage orifice area and morphology is closely associated with flow velocity in patients with nonvalvular atrial fibrillation

Abstract

Background Thromboembolic events are the most serious complication of atrial fibrillation (AF), and the left atrial appendage (LAA) is the most important site of thrombosis in patients with AF. During the period of COVID-19, a non-invasive left atrial appendage detection method is particularly important in order to reduce the exposure of the virus. This study used CT three-dimensional reconstruction methods to explore the relationship between LAA morphology, LAA orifice area and its mechanical function in patients with non-valvular atrial fibrillation (NVAF). Methods A total of 81 consecutive patients with NVAF (36 cases of paroxysmal atrial fibrillation and 45 cases of persistent atrial fibrillation) who were planned to undergo catheter radiofrequency ablation were enrolled. All patients were examined by transthoracic echocardiography (TTE), TEE, and computed tomography angiography (CTA) before surgery. The LAA orifice area was obtained according to the images of CTA. According to the left atrial appendage morphology, it was divided into chicken wing type and non-chicken wing type. At the same time, TEE was performed to determine left atrial appendage flow velocity (LAAFV), and the relationship between the left atrial appendage orifice area and LAAFV was analyzed. Results The LAAFV in Non-chicken wing group was lower than that in Chicken wing group (36.2 ± 15.0 cm/s vs. 49.1 ± 22.0 cm/s, p-value < 0.05). In the subgroup analysis, the LAAFV in Non-chicken wing group was lower than that in Chicken wing group in the paroxysmal AF (44.0 ± 14.3 cm/s vs. 60.2 ± 22.8 cm/s, p-value < 0.05). In the persistent AF, similar results were observed (29.7 ± 12.4 cm/s vs. 40.8 ± 17.7 cm/s, p-value < 0.05). The LAAFV in persistent AF group was lower than that in paroxysmal AF group (34.6 ± 15.8 cm/s vs. 49.9 ± 20.0 cm/s, p-value < 0.001). The LAAFV was negatively correlated with left atrial dimension (R = − 0.451, p-value < 0.001), LAA orifice area (R= − 0.438, p-value < 0.001) and left ventricular mass index (LVMI) (R= − 0.624, p-value < 0.001), while it was positively correlated with LVEF (R = 0.271, p-value = 0.014). Multiple linear regression analysis showed that LAA morphology (β = − 0.335, p-value < 0.001), LAA orifice area (β = − 0.185, p-value = 0.033), AF type (β = − 0.167, p-value = 0.043) and LVMI (β = − 0.465, p-value < 0.001) were independent factors of LAAFV. Conclusions The LAA orifice area is closely related to the mechanical function of the LAA in patients with NVAF. The larger LAA orifice area and LVMI, Non-chicken wing LAA and persistent AF are independent predictors of decreased mechanical function of LAA, and these parameters might be helpful for better management of LA thrombosis.

Morphological changes in the orifices of the left atrial appendage and left atrium in patients with atrial fibrillation

“…The minor axis of the LAA orifice in the AF group was longer than that of the control group, but the major axis of the two groups was similar. As a result, the shape of the LAA orifice changed from oval to circular in AF patients, which might affect the hemodynamics and accelerate thrombus formation of the LAA ( 18 , 19 ), even though it was not an independent risk factor of AF as compared with LAA volume and LA volume.…”

Stroke risk evaluation for patients with atrial fibrillation: Insights from left atrial appendage

“…In a multi-linear regression analysis, LAA morphology was found to be the significant determinant of LAA flow velocity ( 99 ). In other studies, flow velocity was shown to be negatively correlated with orifice size, and many studies found that a greater orifice size usually resulted in decreased flow velocity ( 32 , 47 , 53 ). CFD was also applied in studies relevant to morphology parameters in which LAA length, orifice area, tortuosity, etc.…”

“…This seems more accurate and less subjective compared to the intuitive definition, and is used as the measurement method for LAA orifice in ( 52 ). However, several studies have defined the LAA orifice as the narrowest portion at the entrance into the left atrium ( 49 , 53 ). We deduced that this wide-spread definition had its origins in studies of LAA occlusion, as the location of occlusion is usually defined as the narrowest portion ( Figure 3 , orange dashed line), which would be defined as the LAA neck in our context.…”

“…In addition to the above-mentioned characteristics, some other characteristics were also studied, such as the angle of LAA bend ( 59 ), the depth ( 48 , 53 ) (see Figures 2D,E ) and the number of lobes ( 52 , 60 ). In these studies, the acute angle, increased depth and large number of lobes was each considered as a high-risk morphology of LAA.…”

Construction of a Clinical Predictive Model of Left Atrial and Left Atrial Appendage Thrombi in Patients with Nonvalvular Atrial Fibrillation

“…constructed a model for predicting LAAT based on three independent risk factors: left atrial appendage emptying velocity (LAAEV), LA or LAASEC, and less than moderate to severe mitral regurgitation [AUC = 0.88, 95% CI: 0.82–0.95]. LAAEV [ 22 , 23 ] and LAA morphology [ 24 ] are often considered risk factors for LAAT, but considering that they are mainly measured by TEE, they are not included in multivariate analysis. Due to the different medical levels of center levels, we tried to choose simple and easily available indicators for further research.…”