Latest incidence and electrocardiographic predictors of atrial fibrillation: a prospective study from China / 中华医学杂志(英文版)

BACKGROUND@#China bears the biggest atrial fibrillation (AF) burden in the world. However, little is known about the incidence and predictors of AF. This study aimed to investigate the current incidence of AF and its electrocardiographic (ECG) predictors in general community individuals aged over 60 years in China.@*METHODS@#This was a prospective cohort study, recruiting subjects who were aged over 60 years and underwent annual health checkups from April to July 2015 in four community health centers in Songjiang District, Shanghai, China. The subjects were then followed up from 2015 to 2019 annually. Data on sociodemographic characteristics, medical history, and the resting 12-lead ECG were collected. Kaplan-Meier curve was used for showing the trends in AF incidence and calculating the predictors of AF. Associations of ECG abnormalities and AF incidence were examined using Cox proportional hazard models.@*RESULTS@#This study recruited 18,738 subjects, and 351 (1.87%) developed AF. The overall incidence rate of AF was 5.2/1000 person-years during an observation period of 67,704 person-years. Multivariable Cox regression analysis indicated age (hazard ratio [HR], 1.07; 95% confidence interval [CI]: 1.06-1.09; P < 0.001), male (HR, 1.30; 95% CI: 1.05-1.62; P = 0.018), a history of hypertension (HR, 1.55; 95% CI: 1.23-1.95; P < 0.001), a history of cardiac diseases (HR, 3.23; 95% CI: 2.34-4.45; P < 0.001), atrial premature complex (APC) (HR, 2.82; 95% CI: 2.17-3.68; P < 0.001), atrial flutter (HR, 18.68; 95% CI: 7.37-47.31; P < 0.001), junctional premature complex (JPC) (HR, 3.57; 95% CI: 1.59-8.02; P = 0.002), junctional rhythm (HR, 18.24; 95% CI: 5.83-57.07; P < 0.001), ventricular premature complex (VPC) (HR, 1.76; 95% CI: 1.13-2.75, P = 0.012), short PR interval (HR, 5.49; 95% CI: 1.36-22.19; P = 0.017), right atrial enlargement (HR, 6.22; 95% CI: 1.54-25.14; P = 0.010), and pacing rhythm (HR, 3.99; 95% CI: 1.57-10.14; P = 0.004) were independently associated with the incidence of AF.@*CONCLUSIONS@#The present incidence of AF was 5.2/1000 person-years in the studied population aged over 60 years in China. Among various ECG abnormalities, only APC, atrial flutter, JPC, junctional rhythm, short PR interval, VPC, right atrial enlargement, and pacing rhythm were independently associated with AF incidence.

Effects of activated CD4 + T cell-derived exosomes on cardiac remodeling after myocardial infarction / 中华危重病急救医学

Objective:To explore the role of activated CD4 + T cells in cardiac remodeling after myocardial infarction (MI). Methods:① Experiment in vitro: naive CD4 + T cells were isolated in mouse spleen, and then stimulated with plate-bound anti-CD3 and anti-CD28 for 48 hours. Exosomes isolated from the supernatant of activated CD4 + T cells were incubated with cardiac fibroblasts (CFs) for 48 hours, and then the ability of CFs proliferation, migration and differentiation were detected by cell counting kit-8 (CCK-8) assay, Transwell assay, and immunofluorescence assay. ② Experiment in vivo: 40 male C57 mice were divided into 4 groups according to random number table method, including control group (Ctrl group), sham operation group (Sham group), MI group, and exosome treatment group (MI+Exo group), with 10 in each group. The mice model of MI was established by ligating the left anterior descending coronary artery. In MI+Exo group, 40 μg/d exosomes were injected intravenously into the tail after modeling. Cardiac function and cardiac fibrosis post-MI were assessed by echocardiography and quantitative polymerase chain reaction (qPCR) at 4th week. Results:① In vitro: exosomes derived from activated CD4 + T cells significantly promote CFs proliferation, migration and differentiation [proliferation ability ( A value): 0.31±0.01 vs. 0.21±0.01, migration capability (cells/MP): 79.20±3.34 vs. 48.80±2.13, differentiation ability (α-smooth muscle actin, α-SMA; fluorescence intensity): 1.56±0.03 vs. 1.00±0.02, all P < 0.05]. ② In vivo: echocardiographic analysis showed that exosomes derived from activated CD4 + T cells aggravated the deterioration of cardiac dysfunction post-MI than MI group, as indicated by left ventricular ejection fraction (LVEF) and fractional shortening (FS) decreased significantly [LVEF: 0.185±0.008 vs. 0.257±0.022, FS: (9.72±1.72)% vs. (14.08±1.08)%, both P < 0.05], left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD) increased significantly [LVEDD (mm): 5.43±0.29 vs. 4.62±0.35, LVESD (mm): 4.94±0.12 vs. 3.69±0.29, both P < 0.05]. Additionally, qPCR showed that exosomes derived from activated CD4 + T cells remarkably promoted myocardial fibrosis post-MI than MI group, as indicated by the mRNA expression of α-SMA, collagens (Col1a1, Col3a1) in MI+Exo group was significantly higher than that in MI group [α-SMA (2 -ΔΔCT): 4.72±0.89 vs. 3.58±0.78, Col1a1 (2 -ΔΔCT): 6.59±0.56 vs. 4.23±0.42, Col3a1 (2 -ΔΔCT): 13.40±1.03 vs.4.96±0.36, all P < 0.05]. Conclusion:Activated CD4 + T cells promote cardiac remodeling following MI through transferring exosomes to CFs.