2.1 Study Population
This study enrolled 30 SLE patients (SLE group) treated from September 2019 to July 2020. The patients were further divided into subgroups according to their SELENA-SLEDAI score: SELENA-SLEDAI ≤ 12 (mild-to-moderate group), SELENA-SLEDAI > 12 (severe group). All patients met the diagnostic criteria of SLE established by the American Rheumatology Association (ACR) in 1997. Blood samples were obtained from all patients and laboratory investigations were performed: complete blood count, fasting glucose, low-density lipoproteins (LDL), anti-double stranded DNA (anti-dsDNA), complement component C3 (C3), complement component C4 (C4) and high sensitivity-TropT (hs-TropT). At the same time, 30 healthy people were selected as a control group. All participants were examined using 3D-STI to obtain relevant parameters. The inclusion and exclusion criteria are as follows: inclusion criteria: (1) accorded with the SLE classification standard of the ACR; (2) left ventricular ejection fraction (LVEF) > 55% in the SLE group, and age, sex body mass index et al were matched to the control group; (3) no cardiovascular risk factors and no history of heart disease or other autoimmune diseases; (4) patients in the SLE group were treated regularly and their condition was relatively stable. Exclusion criteria: (1) coexisting hypertension, coronary heart disease, diabetes mellitus, hyperlipidemia, valvular disease, pericardial disease, atrial fibrillation, congenital heart disease, or kidney disease; (2) other autoimmune diseases. All participants were informed of the aim of the study and agreed to participate. The participants signed an informed consent form before the examination, and approval was obtained from the Medical Ethics Committee.
Echocardiography
All participants underwent an echocardiographic examination. The images were collected by ultrasound diagnostic doctors with more than 10 years of experience. The participant was instructed to take the left recumbent position and the electrocardiograph was manually connected. Color Doppler ultrasonography (GE Vivid E9, probe: 4V, frequency: 1.5–4.0 MHz) was used, and the on-machine 3D-STI analysis software was used for post-processing. After the patient was instructed to hold their breath to display a two-dimensional image (clear apical four-chambers), the 4D mode was selected, and three consecutive and stable complete cardiac cycles were collected quickly and without interruption. The frame rate was then adjusted to 40% of the participant’s maximal heart rate, and the image was stored. In the 4D auto LVQ mode, the software automatically tracked the boundaries of the left ventricular wall (endocardium and epicardium) during the complete cardiac cycle. The following 3D routine parameters were obtained: left ventricular end-diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), left ventricular ejection fraction (LVEF), spherical index (SPI), left ventricular end diastolic mass (LV EDmass), and left ventricular end systolic mass (LV ESmass). Besides, the following 3D strain parameters were obtained simultaneously: global longitudinal strain (GLS), global circumferential strain (GCS), left ventricular twist angle (LVtw), torsion (Tor), and peak strain dispersion (PSD), myocardial comprehensive index (MCI = GLS × LVtw).
Statistical Analysis
SPSS 22.0 software was used for statistical analysis, and measurement data were expressed byχ ± s . Single factor analysis of variance (ANOVA ) was used for inter-group comparison and the LSD-tmethod was used for pairwise comparison. Receiver operating characteristic (ROC ) curve analysis was used to evaluate the diagnostic efficacy of the 3D-STI parameters on left ventricular systolic function in patients with SLE, the best cut-off point was determined, F and P values were calculated simultaneously. The correlation between 3D-STI parameters and hs-TropT was analyzed using Pearson’s correlation analysis. Intra-group correlation coefficients (ICC ) were calculated to assess repeatability between and within observers. The difference was statistically significant (P < 0.05).
Results
3.1 Baseline characteristics and laboratory results
Baseline characteristics of the study population are given in Table 1: compared with the mild-to-moderate group, the SELENA-SLEDAI was significantly higher in the severe group (P < 0.05). Laboratory results of the SLE patients are given in Table 2: compared with the mild-to-moderate group, the anti-dsDNA, C3, C4 and hs-TropT were significantly higher in the severe group (P < 0.05).
Table1: baseline characteristics of the study population