The mechanism of thrombotic complications in patients with aortic stenosis (AS) is unclear so far. Our aim was to evaluate the levels of phosphatidylserine (PS) exposed on blood cells, endothelial cells (ECs), and extracellular vesicles (EVs) and its procoagulant activity (PCA) in mild to severe AS patients. Exposed PS on blood cells, ECs and EVs were analyzed by flow cytometry. PCA was evaluated by clotting time (CT), intrinsic factor Xa (FXa), extrinsic FXa, thrombin and fibrin formation assays. We also evaluated the inhibitory effects of lactadherin (Lact) on PCA in AS patients. Our results demonstrated that patients with AS had significantly higher percentages of positive phosphatidylserine (PS+) red blood cells (RBCs), platelets (PLTs), white blood cells (WBCs) and ECs compared to controls. Total EVs with PS+, platelet EVs (PEVs), endothelial-derived EVs (EEVs) and positive tissue factor EVs (TF+EVs) levels were significantly higher in mild to severe AS. In addition, we further confirmed that PS+ blood cells, ECs and EVs significantly contributed to shortened CT and dramatically increased FXa, thrombin and final fibrin generation in mild to severe AS compared to controls. Furthermore, lactadherin significantly inhibited the PCA of PS exposure on blood cells, ECs and EVs in AS patients, whereas anti-TF had no this effect. Our study revealed a previously unrecognized association between exposed PS levels on blood cells, ECs and EVs and PCA in AS. Lactadherin promises to be a new therapy by blocking PS to prevent thrombosis in AS patients.

BACKGROUND:Patients with severe aortic stenosis, undergoing transcatheter aortic valve replacement (TAVR), are more likely to develop thrombotic complications. However, the definite mechanisms underlying the hypercoagulation state remain unclear to date. Our objectives were to explore whether and how neutrophil extracellular traps (NETs) play a procoagulant role in patients after TAVR alone or TAVR with percutaneous coronary intervention within 1 year and further to evaluate their interactions with platelets and endothelial cells. METHODS:The levels of plasma NETs, platelets, and endothelial cell activation markers were analyzed by ELISA. NET formation was observed by immunofluorescence. Procoagulant activity was measured by clotting time, fibrin, and TAT (thrombin-antithrombin) complex generation assays. Phosphatidylserine exposure on cells was assessed by flow cytometry. RESULTS:Compared with pre-TAVR, controls, or severe aortic stenosis without TAVR patients, the plasma NET levels in patients after TAVR alone, especially TAVR with percutaneous coronary intervention, increased from 7 days, peaking at 3 months, and then gradually decreased until the 12th month. Furthermore, neutrophils and plasma from patients post-TAVR are more prone to promote NET formation; NETs from these patients markedly decreased clotting time and increased fibrin and TAT generation. Additionally, a high concentration of NETs induced platelet aggregation and exerted a strong cytotoxic effect on endothelial cells and transformed them into a procoagulant phenotype. CONCLUSIONS:These results lead us to believe that NETs contribute to the hypercoagulability in patients post-TAVR. Our study may provide a new target for preventing thrombotic complications in patients post-TAVR by blocking NET generation.

ObjectiveThe mechanism of asymmetric dimethylarginine (ADMA) in thrombosis in patients with nonvalvular atrial fibrillation (NVAF) is still unclear. Our aim was to investigate the relationship between ADMA and indicators of prethrombotic state in NVAF patients and to analyze the predictive role of ADMA in NVAF thrombosis. MethodsA total of 192 NVAF patients were continuously selected from January 2023 to October 2023. Plasma ADMA levels were measured by high-performance liquid chromatography. P-selectin (P-sel), von Willebrand factor (vWF), D-dimer (D-D), and plasminogen activator inhibitor-1 (PAI-1) levels were measured by enzyme-linked immunosorbent assay (ELISA). Nitric oxide (NO) levels were measured by the nitrate reductase assay for plasma nitrite/nitrate, then the Griess method (Shanghai Hailian Biotechnology Co., Shanghai, China) was used to calculate plasma NO levels. ResultsIn our study, ADMA levels were significantly elevated and positively correlated with P-sel, vWF, D-D, and PAI-1, whereas NO levels were significantly negatively correlated with these prethrombotic factors in NVAF. Furthermore, multifactorial logistic regression analysis showed that ADMA and LA diameter were independent predictors of high thrombosis risk (CHA2DS2-VASc >= 2 score) in patients with NVAF. ConclusionsOur findings suggested that ADMA correlated with the prethrombotic state in NVAF and that reduction of ADMA levels in NVAF patients may be a novel therapeutic strategy for thrombosis risk reduction.

Introduction: Coronary slow flow phenomena (CSFP) are associated with endothelial and blood component abnormalities in coronary arteries. Asymmetric dimethylarginine (ADMA) can damage the endothelium of the heart or blood vessels in patients with non-valvular atrial fibrillation (NVAF), causing changes in levels of biological indicators. Our aim was to analyze the relationship between ADMA and CSFP in NVAF patients. Methods: We consecutively enrolled 134 patients diagnosed with NVAF and underwent coronary angiography, 50 control patients without a history of atrial fibrillation and with normal coronary angiographic flow were included at the same time. Based on the corrected TIMI frame count (CTFC), the NVAF patients were categorized into two groups, CTFC ≤27 frames and CTFC >27 frames. Plasma ADMA, P-selectin (p-sel), von Willebrand factor (vWF), D-dimer (D-Di), plasminogen activator inhibitor 1 (PAI-1), and nitric oxide (NO) were detected by ELISA in the different groups. Results: We found that plasma ADMA levels were significantly higher among NVAF patients in the CTFC >27 grade group compared with the control or CTFC ≤27 group. In addition, the levels of blood cells and endothelium-related biomarkers (NO, P-selectin, vWF, D-Di, and PAI-1) were significantly altered and correlated with ADMA levels. Multifactorial analysis showed that plasma ADMA (odd ratio [OR; 95% CI]: 1.65 [1.21–2.43], p < 0.001) and left atrial internal diameter (OR [95% CI]: 1.04 [1.02, 1.1], p < 0.001) could be used as independent risk factors for the development of CSFP in patients with NVAF. The ROC curves of ADMA can predict the development of CSFP in NVAF patients. The minimum diagnostic concentration for the development of CSFP in patients was 2.31 µmol/L. Conclusion: Our study demonstrated that CSFP in NVAF patients was associated with high levels of ADMA and left atrial internal diameter. Therefore, aggressive preoperative detection and evaluation of ADMA and left atrial internal diameter can help deal with the intraoperative presence of CSFP.

Objective:To investigate the predictive factors of delayed high atrioventricular block(DH-AVB) after transcatheter aortic valve replacement(TAVR) and the risk of pacemaker implantation.Methods:Patients who underwent TAVR in the heart center of Qingdao Municipal Hospital from January 2019 to October 2022 were retrospectively analyzed. A total of 85 patients who met the criteria of transcatheter aortic valve replacement were included in this study. They were divided into DH-AVB group after TAVR and non-DH-AVB group after TAVR. The data were analyzed by univariate analysis and binary logistic regression analysis. Results:The results showed that the over-rate of valve implantation( OR=3.582, 95% CI: 0.923-13.902, P=0.048), the depth of valve implantation( OR=3.727, 95% CI: 1.138-12.204, P=0.030), the new postoperative CLBBB( OR=5.958, 95% CI: 1.258-28.220, P=0.025)and the prolonged PR time limit( OR=1.036, 95% CI: 1.008-1.065, P=0.011) were independent risk factors for DH-AVB after TAVR. With the progress of conduction block, patients in DH-AVB group had a higher pacemaker implantation rate(81.82 % vs.18.18 %, P<0.001). Conclusion:The excessive rate of valve implantation, the depth of valve implantation, the new complete left bundle branch block(CLBBB) and the prolonged PR time after operation are independent predictors of delayed complete atrioventricular block after TAVR. The incidence of pacemaker implantation in patients with delayed complete atrioventricular block after operation is higher.