Long-term coagulation abnormalities after COVID-19.

Objective: Hypercoagulation and high incidence of thrombosis during COVID-19 is well established. However, there is a lack of data, how it changes over time. The main purpose of our study was to access different parts of hemostasis in few months after acute disease. Material and methods. Patients discharged from our hospital were invited for follow up examination in 2,3-3,8 (group 1 - 55 pts) or 4,6-5,7 months (group 2 - 45 pts) after admission. Control group (37 healthy adults) had been collected before pandemic started. Standard coagulation tests, aggregometry, thrombodynamics and fibrinolysis results were compared between groups. Result(s): D-dimer was significantly higher, and was APPT was significantly lower in group 2 compared to group 1, while fibrinogen, prothrombin levels didn't differ. Platelet aggregation induced by ASA, ADP, TRAP, spontaneous aggregation didn't differ significantly between groups. Thrombodynamics revealed hypocoagulation in both group 1 and group 2 compared to control: V, mum/min 27,3 (Interquartile range (IQR) 26,3;29,4) and 28,3 (IQR 26,5;30,1) vs. 32,6 (IQR 30,4;35,9) respectively;all p < 0,001. Clot size and density in both group 1 and group 2 were significantly lower than in control group. Fibrinolysis appeared to be enhanced in x2 compared to control and group 1. Lysis progression, %/min was higher: 3,5 (2,5;4,8) vs. 2,4 (1,6;3,5) and 2,6 (2,2;3,4) respectively, all p < 0,05. Lysis onset time in both group 1 and group 2 was significantly shorter compared to control. Conclusion(s): We revealed normalization of parameters of clot formation process in 2-6 months after COVID-19, while fibrinolysis remained still enhanced. Further study is required to investigate the clinical significance of these changes.Copyright © Creative Cardiology 2021.

Multiple Electrode Aggregometry (Multiplate): Functional Assay for Vaccine-Induced (Immune) Thrombotic Thrombocytopenia (VITT).

Vaccine-induced immune thrombotic thrombocytopenia (VITT) was first described in 2021 and represents an adverse reaction to adenoviral vector COVID-19 vaccines AstraZeneca ChAdOx1 nCoV-19 (AZD1222) and Johnson & Johnson Ad26.COV2.S vaccine. VITT is a severe immune platelet activation syndrome with an incidence of 1-2 per 100,000 vaccinations. The features of VITT include thrombocytopenia and thrombosis within 4-42 days of first dose of vaccine. Affected individuals develop platelet-activating antibodies against platelet factor 4 (PF4). The International Society on Thrombosis and Haemostasis recommends both an antigen-binding assay (enzyme-linked immunosorbent assay, ELISA) and a functional platelet activation assay for the diagnostic workup of VITT. Here, the application of multiple electrode aggregometry (Multiplate) is presented as a functional assay for VITT.

Plasma Fibrinogen Independently Predicts Hypofibrinolysis in Severe COVID-19.

High rates of thrombosis are present in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Deeper insight into the prothrombotic state is essential to provide the best thromboprophylaxis care. Here, we aimed to explore associations among platelet indices, conventional hemostasis parameters, and viscoelastometry data. This pilot study included patients with severe COVID-19 (n = 21) and age-matched controls (n = 21). Each patient received 100 mg aspirin therapy at the time of blood sampling. Total platelet count, high immature platelet fraction (H-IPF), fibrinogen, D-dimer, Activated Partial Thromboplastin Time, von Willebrand factor antigen and von Willebrand factor ristocetin cofactor activity, plasminogen, and alpha2-antiplasmin were measured. To monitor the aspirin therapy, a platelet function test from hirudin anticoagulated whole blood was performed using the ASPI test by Multiplate analyser. High on-aspirin platelet reactivity (n = 8) was defined with an AUC > 40 cut-off value by ASPI tests. In addition, in vitro viscoelastometric tests were carried out using a ClotPro analyser in COVID-associated thromboembolic events (n = 8) (p = 0.071) nor the survival rate (p = 0.854) showed associations with high on-aspirin platelet reactivity status. The platelet count (p = 0.03), all subjects. COVID-19 patients presented with higher levels of inflammatory markers, compared with the controls, along with evidence of hypercoagulability by ClotPro. H-IPF (%) was significantly higher among non-survivors (n = 18) compared to survivors (p = 0.011), and a negative correlation (p = 0.002) was found between H-IPF and plasminogen level in the total population. The platelet count was significantly higher among patients with high on-aspirin platelet reactivity (p = 0.03). Neither the ECA-A10 (p = 0.008), and ECA-MCF (p = 0.016) were significantly higher, while the tPA-CFT (p < 0.001) was significantly lower among patients with high on-aspirin platelet reactivity. However, only fibrinogen proved to be an independent predictor of hypofibrinolysis in severe COVID-19 patients. In conclusion, a faster developing, more solid clot formation was observed in aspirin 'non-responder' COVID-19 patients. Therefore, an individually tailored thromboprophylaxis is needed to prevent thrombotic complications, particularly in the hypofibrinolytic cluster.

Platelet Reactivity and Coagulation Markers in Patients with COVID-19.

INTRODUTION: COVID-19 is associated with an increased risk of thrombotic events. However, the contribution of platelet reactivity (PR) to the aetiology of the increased thrombotic risk associated with COVID-19 remains unclear. Our aim was to evaluate PR in stable patients diagnosed with COVID-19 and hospitalized with respiratory symptoms (mainly dyspnoea and dry cough), in comparison with a control group comprised of non-hospitalized healthy controls. METHODS: Observational, case control study that included patients with confirmed COVID-19 (COVID-19 group, n = 60) and healthy individuals matched by age and sex (control group, n = 60). Multiplate electrode aggregometry (MEA) tests were used to assess PR with adenosine diphosphate (MEA-ADP, low PR defined as < 53 AUC), arachidonic acid (MEA-ASPI, low PR < 86 AUC) and thrombin receptor-activating peptide 6 (MEA-TRAP, low PR < 97 AUC) in both groups. RESULTS: The rates of low PR with MEA-ADP were 27.5% in the COVID-19 group and 21.7% in the control group (OR = 1.60, p = 0.20); with MEA-ASPI, the rates were, respectively, 37.5% and 22.5% (OR = 3.67, p < 0.001); and with MEA-TRAP, the incidences were 48.5% and 18.8%, respectively (OR = 9.58, p < 0.001). Levels of D-dimer, fibrinogen, and plasminogen activator inhibitor 1 (PAI-1) were higher in the COVID-19 group in comparison with the control group (all p < 0.05). Thromboelastometry was utilized in a subgroup of patients and showed a hypercoagulable state in the COVID-19 group. CONCLUSION: Patients hospitalized with non-severe COVID-19 had lower PR compared to healthy controls, despite having higher levels of D-dimer, fibrinogen, and PAI-1, and hypercoagulability by thromboelastometry. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT04447131.

Point of care diagnostic of hypercoagulability and platelet function in COVID-19 induced acute respiratory distress syndrome: a retrospective observational study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) associated coagulopathy (CAC) leads to thromboembolic events in a high number of critically ill COVID-19 patients. However, specific diagnostic or therapeutic algorithms for CAC have not been established. In the current study, we analyzed coagulation abnormalities with point-of-care testing (POCT) and their relation to hemostatic complications in patients suffering from COVID-19 induced Acute Respiratory Distress Syndrome (ARDS). Our hypothesis was that specific diagnostic patterns can be identified in patients with COVID-19 induced ARDS at risk of thromboembolic complications utilizing POCT. METHODS: This is a single-center, retrospective observational study. Longitudinal data from 247 rotational thromboelastometries (Rotem®) and 165 impedance aggregometries (Multiplate®) were analysed in 18 patients consecutively admitted to the ICU with a COVID-19 induced ARDS between March 12th to June 30th, 2020. RESULTS: Median age was 61 years (IQR: 51-69). Median PaO2/FiO2 on admission was 122 mmHg (IQR: 87-189), indicating moderate to severe ARDS. Any form of hemostatic complication occurred in 78 % of the patients with deep vein/arm thrombosis in 39 %, pulmonary embolism in 22 %, and major bleeding in 17 %. In Rotem® elevated A10 and maximum clot firmness (MCF) indicated higher clot strength. The delta between EXTEM A10 minus FIBTEM A10 (ΔA10) > 30 mm, depicting the sole platelet-part of clot firmness, was associated with a higher risk of thromboembolic events (OD: 3.7; 95 %CI 1.3-10.3; p = 0.02). Multiplate® aggregometry showed hypoactive platelet function. There was no correlation between single Rotem® and Multiplate® parameters at intensive care unit (ICU) admission and thromboembolic or bleeding complications. CONCLUSIONS: Rotem® and Multiplate® results indicate hypercoagulability and hypoactive platelet dysfunction in COVID-19 induced ARDS but were all in all poorly related to hemostatic complications..

Aggregometry and thromboelastography to identify the timing to trach a COVID-19 patient receiving both antiplatelet therapy and enoxaparin.

In COVID-19 patients receiving enoxaparin and antiplatelets therapy, aggregometry and thromboelastography might be considered an adjunctive tool to identify the time to perform procedures at risk of bleeding, such as tracheostomy.