Vaccine-induced immune thrombotic thrombocytopenia: current evidence, potential mechanisms, clinical implications, and future directions.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) (also termed thrombosis with thrombocytopenia syndrome or vaccine-induced thrombotic thrombocytopenia or vaccine-induced immune thrombocytopenia) is characterized by (i) venous or arterial thrombosis; (ii) mild-to-severe thrombocytopenia; (iii) positive antiplatelet factor 4 (PF4)-polyanion antibodies or anti-PF4-heparin antibodies detected by the HIT (heparin-induced thrombocytopenia) ELISA; (iv) occurring 5-30 days after ChAdOx1 nCoV-19 (AstraZeneca) or Ad26.COV2.S (Johnson & Johnson/Janssen) vaccination. VITT's incidence is 1 per 100 000 vaccinated people irrespective of age and up to 1 in 50 000 for people <50 years of age with the AstraZeneca COVID-19 vaccine. The exact mechanism by which adenovirus-vectored COVID-19 vaccines trigger this syndrome is still unclear, as for the increased risk for acute cerebral sinus venous thrombosis and splanchnic vein thrombosis as compared to other locations of venous thrombotic events. VITT is associated with the detection of anti-PF4 antibodies, unrelated to previous use of heparin therapy. PF4 antibodies are thought to activate platelets via the platelet FcγRIIA receptors leading to further platelet activation that causes thrombosis and thrombocytopenia.

Microparticles in COVID-19 as a link between lung injury extension and thrombosis.

Procoagulant microparticles are associated with the extent of lung injuries in #COVID19 and pulmonary thrombosis https://bit.ly/3eX2LPc.

Acute Pulmonary Embolism in Patients with and without COVID-19.

INTRODUCTION: Acute pulmonary embolism (APE) is a frequent condition in patients with COVID-19 and is associated with worse outcomes. Previous studies suggested an immunothrombosis instead of a thrombus embolism, but the precise mechanisms remain unknown. OBJECTIVE: To assess the determinants and prognosis of APE during COVID-19. METHODS: We retrospectively included all consecutive patients with APE confirmed by computed tomography pulmonary angiography hospitalized at Strasbourg University Hospital from 1 March to 31 May 2019 and 1 March to 31 May 2020. A comprehensive set of clinical, biological, and imaging data during hospitalization was collected. The primary outcome was transfer to the intensive care unit (ICU). RESULTS: APE was diagnosed in 140 patients: 59 (42.1%) with COVID-19, and 81 (57.9%) without COVID-19. A 812% reduction of non-COVID-19 related APE was registered during the 2020 period. COVID-19 patients showed a higher simplified pulmonary embolism severity index (sPESI) score (1.15 ± 0.76 vs. 0.83 ± 0.83, p = 0.019) and were more frequently transferred to the ICU (45.8% vs. 6.2%, p < 0.001). No difference regarding the most proximal thrombus localization, Qanadli score (8.1 ± 6.9 vs. 9.0 ± 7.4, p = 0.45), the proportion of subsegmental (10.2% vs. 11.1%, p = 0.86), and segmental pulmonary embolism (35.6% vs. 24.7%, p = 0.16) was evidenced between COVID-19 and non-COVID-19 APE. In COVID-19 patients with subsegmental or segmental APE, thrombus was, in all cases (27/27 patients), localized in areas with COVID-19-related lung injuries. Marked inflammatory and prothrombotic biological markers were associated with COVID-19 APE. CONCLUSIONS: APE patients with COVID-19 have a particular clinico-radiological and biological profile and a dismal prognosis. Our results emphasize the preeminent role of inflammation and a prothrombotic state in these patients.

D-Dimers Level as a Possible Marker of Extravascular Fibrinolysis in COVID-19 Patients.

BACKGROUND AND OBJECTIVE: Host defence mechanisms to counter virus infection include the activation of the broncho-alveolar haemostasis. Fibrin degradation products secondary to extravascular fibrin breakdown could contribute to the marked increase in D-Dimers during COVID-19. We sought to examine the prognostic value on lung injury of D-Dimers in non-critically ill COVID-19 patients without thrombotic events. METHODS: This study retrospectively analysed hospitalized COVID-19 patients classified according to a D-Dimers threshold following the COVID-19 associated haemostatic abnormalities (CAHA) classification at baseline and at peak (Stage 1: D-Dimers less than three-fold above normal; Stage 2: D-Dimers three- to six-fold above normal; Stage 3: D-Dimers six-fold above normal). The primary endpoint was the occurrence of critical lung injuries on chest computed tomography. The secondary outcome was the composite of in-hospital death or transfer to the intensive care unit (ICU). RESULTS: Among the 123 patients included, critical lung injuries were evidenced in 8 (11.9%) patients in Stage 1, 6 (20%) in Stage 2 and 15 (57.7%) in Stage 3 (p = 0.001). D-Dimers staging at peak was an independent predictor of critical lung injuries regardless of the inflammatory burden assessed by CRP levels (OR 2.70, 95% CI (1.50-4.86); p < 0.001) and was significantly associated with increased in-hospital death or ICU transfer (14.9 % in Stage 1, 50.0% in Stage 2 and 57.7% in Stage 3 (p < 0.001)). D-Dimers staging at peak was an independent predictor of in-hospital death or ICU transfer (OR 2.50, CI 95% (1.27-4.93); p = 0.008). CONCLUSIONS: In the absence of overt thrombotic events, D-Dimers quantification is a relevant marker of critical lung injuries and dismal patient outcome.

D-Dimers Level as a Possible Marker of Extravascular Fibrinolysis in COVID-19 Patients

Background and Objective: Host defence mechanisms to counter virus infection include the activation of the broncho-alveolar haemostasis. Fibrin degradation products secondary to extravascular fibrin breakdown could contribute to the marked increase in D-Dimers during COVID-19. We sought to examine the prognostic value on lung injury of D-Dimers in non-critically ill COVID-19 patients without thrombotic events. Methods: This study retrospectively analysed hospitalized COVID-19 patients classified according to a D-Dimers threshold following the COVID-19 associated haemostatic abnormalities (CAHA) classification at baseline and at peak (Stage 1: D-Dimers less than three-fold above normal;Stage 2: D-Dimers three- to six-fold above normal;Stage 3: D-Dimers six-fold above normal). The primary endpoint was the occurrence of critical lung injuries on chest computed tomography. The secondary outcome was the composite of in-hospital death or transfer to the intensive care unit (ICU). Results: Among the 123 patients included, critical lung injuries were evidenced in 8 (11.9%) patients in Stage 1, 6 (20%) in Stage 2 and 15 (57.7%) in Stage 3 (p = 0.001). D-Dimers staging at peak was an independent predictor of critical lung injuries regardless of the inflammatory burden assessed by CRP levels (OR 2.70, 95% CI (1.50–4.86);p <0.001) and was significantly associated with increased in-hospital death or ICU transfer (14.9 % in Stage 1, 50.0% in Stage 2 and 57.7% in Stage 3 (p <0.001)). D-Dimers staging at peak was an independent predictor of in-hospital death or ICU transfer (OR 2.50, CI 95% (1.27–4.93);p = 0.008). Conclusions: In the absence of overt thrombotic events, D-Dimers quantification is a relevant marker of critical lung injuries and dismal patient outcome.

Increased susceptibility to SARS-CoV-2 infection in patients with reduced left ventricular ejection fraction.

AIMS: Cardiovascular disease has been recognized as a major determinant of coronavirus disease 2019 (COVID-19) vulnerability and severity. Angiotensin-converting enzyme (ACE) 2 is a functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is up-regulated in patients with heart failure. We sought to examine the potential association between reduced left ventricular ejection fraction (LVEF) and the susceptibility to SARS-CoV-2 infection. METHODS AND RESULTS: Of the 1162 patients with acute coronary syndrome (ACS) who underwent percutaneous coronary intervention between February 2014 and October 2018, we enrolled 889 patients with available clinical follow-up data. Follow-up was conducted by telephone interviews 1 month after the start of the French lockdown which began on 17 March 2020. Patients were divided into two groups according to LVEF <40% (reduced LVEF) (n = 91) or ≥40% (moderately reduced + preserved LVEF) (n = 798). The incidence of COVID-19-related hospitalization or death was significantly higher in the reduced LVEF group as compared with the moderately reduced + preserved LVEF group (9% vs. 1%, P < 0.001). No association was found between discontinuation of ACE-inhibitor or angiotensin-receptor blockers and COVID-19 test positivity. By multivariate logistic regression analysis, reduced LVEF was an independent predictor of COVID-19 hospitalization or death (odds ratio: 6.91, 95% confidence interval: 2.60 to 18.35, P < 0.001). CONCLUSIONS: In a large cohort of patients with previous ACS, reduced LVEF was associated with increased susceptibility to COVID-19. Aggressive COVID-19 testing and therapeutic strategies may be considered for patient with impaired heart function.

Staging Severity of COVID-19 according to Hemostatic Abnormalities (CAHA Score).

This is the first study to show a stepwise increase in venous thrombotic events according to COVID-19 coagulopathy (COVID-19-associated hemostatic abnormalities [CAHA]) staging and lung injuries assessed by chest computed tomography. Excess mortality and/or transfer to intensive care unit according to CAHA staging.

Thromboprophylaxis: balancing evidence and experience during the COVID-19 pandemic.

A common and potent consideration has recently entered the landscape of the novel coronavirus disease of 2019 (COVID-19): venous thromboembolism (VTE). COVID-19 has been associated to a distinctive related coagulopathy that shows unique characteristics. The research community has risen to the challenges posed by this « evolving COVID-19 coagulopathy ¼ and has made unprecedented efforts to promptly address its distinct characteristics. In such difficult time, both national and international societies of thrombosis and hemostasis released prompt and timely responses to guide recognition and management of COVID-19-related coagulopathy. However, latest guidelines released by the international Society on Thrombosis and Haemostasis (ISTH) on May 27, 2020, followed the American College of Chest Physicians (CHEST) on June 2, 2020 showed some discrepancies regarding thromboprophylaxis use. In this forum article, we would like to offer an updated focus on thromboprophylaxis with current incidence of VTE in ICU and non-ICU patients according to recent published studies; highlight the main differences regarding ISTH and CHEST guidelines; summarize and describe which are the key ongoing RCTs testing different anticoagulation strategies in patients with COVID-19; and finally set a proposal for COVID-19 coagulopathy specific risk factors and dedicated trials.