Research objects
A retrospective analysis of patients with NVAF who were hospitalized in the Department of Cardiology, Affiliated Hospital of Xuzhou Medical University from November 2016 to November 2020. Inclusion criteria included AF was diagnosed by ECG or 24-hour Holter, all patients received TTE, TEE, and CTA examinations, and the interval between TEE and CTA examinations was within 48 hours, patients with paroxysmal AF show sinus rhythm during TEE examination, and those with persistent AF show an AF rhythm. Exclusion criteria included incomplete clinical data, complications with valvular heart disease (moderate to severe mitral valve stenosis), patent foramen ovale, artificial valve replacement, poor CT image quality and complete LAA data that could not be obtained, severe liver and kidney dysfunction, patients with thyroid disease or multiple organ dysfunction, etc. Finally, a total of 81 patients were selected, including 36 cases (44.4%) with paroxysmal AF and 45 cases (55.6%) with persistent AF, with an average age of 61.8 ± 8.8 years. The basic clinical data of the patients are shown in Table 1.
Table 1
Clinical data of the study population
Variables
|
All population(n = 81)
|
PaAF (n = 36)
|
PeAF (n = 45)
|
P-value
|
Age (years)
|
61.8 ± 8.8
|
63.2 ± 8.8
|
60.7 ± 8.8
|
0.198
|
Male (n, %)
|
57(70.4)
|
26(72.2)
|
31(68.9)
|
0.744
|
BMI (kg/m²)
|
25.6 ± 3.0
|
25.5 ± 3.1
|
25.7 ± 3.0
|
0.722
|
Hypertension (n,%)
|
30(37.0)
|
12(33.3)
|
18(40.0)
|
0.537
|
Diabetes (n,%)
|
11(13.6)
|
5(13.9)
|
6(13.3)
|
1.000
|
CAD (n,%)
|
27(33.3)
|
13(36.1)
|
14(31.1)
|
0.635
|
Past Stroke (n,%)
|
16(19.8)
|
5(13.9)
|
11(24.4)
|
0.236
|
CHF (n,%)
|
11(13.6)
|
6(16.7)
|
5(11.1)
|
0.690
|
Smokers (n,%)
|
24(29.6)
|
13(36.1)
|
11(24.4)
|
0.253
|
CHA2DS2-VAScscores
|
2.1 ± 1.6
|
2.1 ± 1.6
|
2.2 ± 1.6
|
0.730
|
Diagnostic criteria for atrial fibrillation
The electrocardiogram or 24-hour Holter electrocardiogram showed the disappearance of P waves and replaced them with f waves of different sizes, shapes, and amplitudes. The frequency of the f wave is 350 to 600 times/min, and the R-R interval is absolutely unequal (Fig. 1). According to the duration of AF, it is divided into paroxysmal AF (PaAF) and persistent AF (PeAF). PaAF is defined as AF that terminates within 7 days, and PeAF is defined as AF that lasts more than 7 days [13].
Transthoracic echocardiography (TTE) examination
A Philips EPIQ 7c ultrasonic diagnostic apparatus, S5-1 probe, and probe with a frequency 1–5 MHz were used. The patient was placed in the left decubitus position, and the patient's left atrium anteroposterior diameter, left ventricular end-diastolic diameter, left ventricular ejection fraction (measured by biplane Simpson method), left ventricular posterior wall thickness, ventricular septal thickness and other parameters were recorded in detail.
TEE examination and the determination of LAAFV
A Philips iE33 color Doppler ultrasound diagnostic apparatus and a X7-2t transesophageal matrix real-time 3D probe with a frequency of 2–7 MHz were used. Before the examination, patients fasted for 6–8 hours. They were connected to the ECG synchronization recording, the pulse Doppler sampling volume was placed within one-third of the proximal opening of the LAA, and the LAA blood flow spectrum was obtained. The blood flow spectrum of the LAA is a regular two-way wave in sinus rhythm and an irregular sawtooth waveform in AF. The peak value of the positive wave is recorded in 3 and 10 cardiac cycles, which is the maximum row of the LAA. Air velocity and take the average value as the left atrial appendage flow velocity (LAAFV) [14] (Fig. 2–3).
Computed tomography angiography (CTA) and 3D reconstruction
The CT imaging data were acquired by the German Siemens dual-source CT machine (SOMATOM Definition, SIEMENS Germany). Iodomidol (60–80 ml) was injected into the cubital vein at a flow rate of 5 ml/s, and then 50 ml of normal saline was injected at a rate of 5 ml/s. Contrast agent tracking technology triggered enhanced scanning. The following scan parameters were used—trigger plane: ascending aorta root level, trigger threshold: 90–100 Hu, start scanning after 6 s delay, scanning time 5–12 s, scanning range: 1 cm below tracheal carina to 1.5 cm lower edge of the heart, detector width 2.0 mm×32.0 mm×0.6 mm, layer thickness 2.0 mm×64.0 mm×0.6 mm, frame rotation time 330 ms, heart rate dependent pitch 0.2–0.5, tube current 400 mA, and voltage 120 kV.
Measurement of LAA volume and its morphology
The GE AW4.6 Workstation was used to perform 3D reconstruction of the original CT images to obtain 3D images of the LAA and left atrium (LA). Then, a cutting tool was used to separate the LAA from the LA to obtain the LAA volume. According to the morphological characteristics of the LAA, it can be divided into chicken wing (there is an obvious fold at the proximal or middle part of the main lobe of the left atrial appendage) and non-chicken wing (other forms beside chicken wings) (Fig. 4–5).
Measurement of the LAA orifice area
The long diameter (D1) and short diameter (D2) of the LAA orifice were measured by a Philips IntelliSpace Portal workstation. The LAA orifice was manually cross-sectioned from the multiplanar reconstruction image, and the orifice area was determined by its narrowest part. By creating a plane perpendicular to the axis of the left atrial ear neck, a cross-sectional view of the LAA is generated (Fig. 6). The formula 0.785*D1*D2 was used to calculate the LAA orifice area [15].
Statistical analysis
SPSS 22.0 software was used for statistical analysis. Measurement data are expressed as the mean ± standard deviation, and independent sample t-test was used for comparison between groups. Count data are expressed by the number of cases and percentage (%), and the χ2 test or Fisher's exact probability method was used for comparison between groups. T-test or simple linear regression analysis was used to determine each parameter that may affect LAAFV. Then, the findings were incorporated into multiple linear regression analysis to evaluate the independent predictors that determine LAAFV. P < 0.05 was considered statistically significant.