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2.
Hematology ; 27(1): 318-321, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1713441

ABSTRACT

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug reaction associated with thrombosis. Clinical scoring systems and the presence of anti-platelet factor 4 (anti-PF4)/heparin antibodies determine the diagnosis. CASE PRESENTATION: A 57-year-old man who was treated with acenocoumarol due to a chronic left ventricular thrombus was admitted to the hospital for severe SARS-CoV-2 pneumonia and pulmonary embolism. The patient was started on bemiparin and discharged. Left lower limb acute arterial ischemia and thrombocytopenia were diagnosed 18 days later. Computed tomography angiography revealed a large left ventricular thrombus and multiple arterial thrombi. Left femoral-popliteal thromboembolectomy was performed. Anti-PF4/heparin antibodies confirmed an HIT diagnosis. Fondaparinux (7.5 mg/24 h) was initiated, but cardiac surgery was necessary. Bivalirudin was used during surgery, with an initial load (1.25 mg/kg) and maintenance infusion (2.5 mg/kg/h). The cardiac thrombus was extracted, but the patient experienced a postsurgical myocardial infarction. Percutaneous cardiovascular intervention (PCI) required a bivalirudin load (0.75 mg/kg) and maintenance infusion (1.75 mg/kg/h). No coronary lesions were detected, and argatroban was started afterwards (0.5 µg/kg/min). When the platelet count exceeded 100 × 109/L, acenocoumarol was initiated. Thereupon, acetylsalicylic acid (100 mg/24 h) was added. No other complications have been reported to date. CONCLUSION: The clinical presentation of intraventricular and multiple arterial thrombi is remarkable. SARS-CoV-2 infection likely contributed to a hypercoagulable state. The management of patients with HIT undergoing cardiac surgery is challenging. If surgery cannot be delayed, then treatment with bivalirudin is recommended. Additionally, this drug is recommended for PCI. Bivalirudin is safe and well-tolerated in both procedures.


Subject(s)
Acenocoumarol/administration & dosage , Anticoagulants/administration & dosage , Arginine/analogs & derivatives , COVID-19/drug therapy , Heparin , Hirudins/administration & dosage , Peptide Fragments/administration & dosage , Percutaneous Coronary Intervention , Pipecolic Acids/administration & dosage , SARS-CoV-2 , Sulfonamides/administration & dosage , Thrombocytopenia , Thrombosis , Arginine/administration & dosage , COVID-19/complications , Heparin/administration & dosage , Heparin/adverse effects , Humans , Male , Middle Aged , Recombinant Proteins/administration & dosage , Thrombocytopenia/chemically induced , Thrombocytopenia/therapy , Thrombosis/chemically induced , Thrombosis/therapy
6.
Hematology Am Soc Hematol Educ Program ; 2021(1): 614-620, 2021 12 10.
Article in English | MEDLINE | ID: covidwho-1566499

ABSTRACT

COVID-19 is frequently associated with abnormalities on coagulation testing and a coagulopathy driven by inflammation, intravascular coagulation activation, and microvascular thrombosis. Elevated D-dimer is the most common finding and is a predictor of adverse outcomes including thrombosis, critical illness, and death. Although COVID-19-associated coagulopathy has some similarities to disseminated intravascular coagulation, the platelet count is usually preserved, coagulation times are usually normal or minimally prolonged, and thrombosis is more common than bleeding, at least in noncritically ill patients. Bleeding is uncommon but may be a significant problem in critically ill patients, including those who may develop a consumptive coagulopathy with frank disseminated intravascular coagulation and those on extracorporeal membrane oxygenation. Blood product support to correct coagulopathy is reserved for bleeding patients or those requiring invasive procedures. Current recommendations suggest that all hospitalized patients should receive at least a prophylactic dose of anticoagulation. Results from a multiplatform randomized clinical trial suggest that therapeutically dosed anticoagulation may improve outcomes, including the need for organ support and mortality in moderately ill patients but not in those requiring critical care. The results of ongoing trials evaluating the impact of different antithrombotic strategies (therapeutic agents and intensity) on COVID-19 outcomes are eagerly awaited and are expected to have important implications for patient management. We also discuss COVID-19 vaccine-associated cytopenias and bleeding as well as vaccine-induced thrombotic thrombocytopenia, in which thrombosis is associated with thrombocytopenia, elevated D-dimer, and, frequently, hypofibrinogenemia.


Subject(s)
Blood Coagulation , COVID-19 Vaccines/adverse effects , COVID-19/complications , Thrombocytopenia/etiology , Thrombosis/etiology , Anticoagulants/therapeutic use , Blood Coagulation/drug effects , COVID-19/blood , COVID-19/prevention & control , Female , Fibrin Fibrinogen Degradation Products/analysis , Humans , Middle Aged , Thrombocytopenia/blood , Thrombocytopenia/therapy , Thrombophilia/blood , Thrombophilia/etiology , Thrombophilia/therapy , Thrombosis/blood , Thrombosis/therapy
7.
J Thromb Haemost ; 20(1): 149-156, 2022 01.
Article in English | MEDLINE | ID: covidwho-1483925

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but severe immunological reaction to the non-replicable adenoviral vector-based COVID-19 vaccines. Extreme activation of platelets and the coagulation system leads to a high risk of death from venous or arterial thrombosis or secondary hemorrhage. Public and clinician awareness has reduced mortality of VITT by nearly 90%. The World Health Organization provided a guideline in July 2021 on diagnosis and management of VITT (also called thrombosis with thrombocytopenia syndrome, or TTS). Since July 2021, new, clinically relevant information has become available. This update has been summarized by the authors in an informal process with recommendations for low resource environments. We provide new available evidence on VITT to empower clinicians to recognize VITT early, then effectively diagnose and treat the disorder to reduce morbidity and mortality. We strongly encourage production of clear management pathways for primary care settings and hospital settings.


Subject(s)
COVID-19 , Thrombocytopenia , Thrombosis , Vaccines , COVID-19 Vaccines , Humans , SARS-CoV-2 , Thrombocytopenia/chemically induced , Thrombocytopenia/diagnosis , Thrombocytopenia/therapy
8.
Am J Hematol ; 97(1): 119-128, 2022 01 01.
Article in English | MEDLINE | ID: covidwho-1479374

ABSTRACT

Coronavirus disease 19 (COVID-19) is considered a multisystemic disease. Several studies have reported persistent symptoms or late-onset complications after acute COVID-19, including post-COVID-19 hematological disorders. COVID-19-induced coagulopathy, an immunothrombotic state, has been linked to thromboembolic and hemorrhagic events. Late-onset thrombocytopenia related to immune system dysregulation has also been reported as a rare manifestation post COVID-19. Close monitoring of laboratory dynamics is considered essential to identify timely abnormal values that need further investigation, providing supportive care whenever indicated. The role of hematologists is essential in terms of the multidisciplinary approach of long COVID-19. This review summarizes all the available evidence on post-acute COVID-19 hematological complications.


Subject(s)
COVID-19/complications , Hematologic Diseases/etiology , Animals , COVID-19/etiology , COVID-19/therapy , Disease Management , Hematologic Diseases/therapy , Hemorrhagic Disorders/etiology , Hemorrhagic Disorders/therapy , Humans , SARS-CoV-2/isolation & purification , Thrombocytopenia/etiology , Thrombocytopenia/therapy , Thromboembolism/etiology , Thromboembolism/therapy , Thrombosis/etiology , Thrombosis/therapy
9.
Anaesth Crit Care Pain Med ; 40(6): 100963, 2021 12.
Article in English | MEDLINE | ID: covidwho-1471855

ABSTRACT

Argatroban is a direct anti-IIa (thrombin) anticoagulant, administered as a continuous intravenous infusion; it has been approved in many countries for the anticoagulant management of heparin-induced thrombocytopaenia (HIT). Argatroban was recently proposed as the non-heparin anticoagulant of choice for the management of patients diagnosed with Vaccine-induced Immune Thrombotic Thrombocytopaenia (VITT). Immunoglobulins are also promptly intravenously administered in order to rapidly improve platelet count; concomitant therapy with steroids is also often considered. An ad hoc committee of the French Working Group on Haemostasis and Thrombosis members has worked on updated and detailed proposals regarding the management of anticoagulation with argatroban, based on previously released guidance for HIT, and adapted for VITT. In case of VITT, the initial dose to be preferred is 1.0 µg × kg-1 × min-1, with further dose-adjustments based on iterative and frequent clinical and laboratory assessments. It is strongly advised to involve a health practitioner experienced in the management of difficult cases in haemostasis. The first laboratory assessment should be performed 4 h after the initiation of argatroban infusion, with further controls at 2-4-h intervals until steady state, and at least once daily thereafter. Importantly, full anticoagulation should be rapidly achieved in case of widespread thrombosis. Cerebral vein thrombosis (which is typical of VITT) should not call for an overly cautious anticoagulation scheme. Argatroban administration requires baseline laboratory assessment and should rely on an anti-IIa assay to derive argatroban plasma levels using a dedicated calibration, with a target range between 0.5 and 1.5 µg/mL. Target argatroban plasma levels can be refined based on meticulous appraisal of risk factors for bleeding and thrombosis, on frequent reassessments of clinical status with appropriate vascular imaging, and on the changes in daily platelet counts. Regarding the use of aPTT, baseline value and possible causes for alterations of the clotting time must be taken into account. Specifically, in case of VITT, an aPTT ratio (patient's/mean normal clotting time) between 1.5 and 2.5 is suggested, to be refined according to the sensitivity of the reagent to the effect of a direct thrombin inhibitor. The sole use of aPTT is discouraged: one has to resort to a periodical check with an anti-IIa assay at least, with the help of a specialised laboratory if necessary. Dose modifications should proceed in a stepwise manner with 0.1 to 0.2 µg × kg-1 × min-1 up- or downward changes, taking into account the initial dose, laboratory results, and the whole individual setting. Nomograms are available to adjust the infusion rate. Haemoglobin level, platelet count, fibrinogen plasma level and liver tests should be periodically checked, depending on the clinical status, the more so when unstable.


Subject(s)
Thrombocytopenia , Thrombosis , Vaccines , Arginine/analogs & derivatives , Humans , Pipecolic Acids , Sulfonamides , Thrombocytopenia/chemically induced , Thrombocytopenia/therapy
11.
Rev. méd. Urug ; 37(3): e37312, set. 2021. tab, graf
Article in Spanish | WHO COVID, LILACS (Americas) | ID: covidwho-1436538

ABSTRACT

Resumen: Introducción: la vacunación contra SARS-CoV-2 es una herramienta imprescindible en el combate contra la pandemia de COVID-19. La vacuna desarrollada en colaboración entre la Universidad de Oxford y el laboratorio de productos farmacéuticos AstraZeneca (AZN) ha demostrado buena eficacia, pero ha habido reporte de trombosis venosas. Caso clínico: se presenta el caso de un paciente de 70 años, de sexo masculino, que 7 días después de la administración de la primera dosis de la vacuna AZN desarrolla trombosis venosa profunda de ambos miembros inferiores y tromboembolismo pulmonar. Coincide con trombocitopenia de 15.000/mm3, descenso del fibrinógeno y elevación de los D-dímeros. La situación clínica evoca el planteo de trombocitopenia trombótica inducida por vacuna (VITT). Se realizó tratamiento con inmunoglobulinas intravenosas, metilprednisolona y crioprecipitados. Requirió colocación de un filtro de la vena cava inferior. Una vez mejorado el recuento plaquetario se instaló tratamiento anticoagulante con apixaban. Evolucionó favorablemente. Discusión: se trata del primer reporte nacional de VITT. Las trombosis subsiguientes a la vacuna de AZN pueden verse con las vacunas que comparten la misma plataforma vacunal (adenovirus inactivado). Se han reportado casos fundamentalmente en menores de 60 años y en topografías inhabituales. Este caso tiene la particularidad de que se trata de un paciente mayor de 60 años, que ya había tenido COVID-19 cinco meses antes y que se presenta con una trombosis en sitios habituales. El manejo terapéutico se adecuó a las pautas internacionales. El caso deja un aprendizaje relevante tanto en lo que refiere al diagnóstico precoz como al manejo terapéutico.


Abstract: Introduction: vaccines against SARS-CoV-2 are an essential tool against the COVID-19 pandemic. The vaccine developed in collaboration with the University of Oxford and the AstraZeneca (AZN) laboratory has proved to be effective, although venous thrombosis have been reported. Clinical case: the study presents the case of a 70 year old male patient who, 7 days after receiving the first dose of the AZN vaccination develops deep vein thrombosis (DVT) in the lower extremities and pulmonary embolism. Simultaneously, thrombocytopenia is 15.000/mm3, fibrinogen levels drop D-dimer levels are elevated. The clinical situation leads to the suspicion of vaccine-associated immune thrombosis and thrombocytopenia (VITT). The patient was treated with intravenous immune globulin, methylprednisolone and cryoprecipitates, requiring a filter to be placed in the inferior vena cava. Once platelets count improved, anti-coagulation therapy including apixaban was commenced, evolution being good. Discussion: this is the first national report on VITT. Thrombosis after the AZN vaccination may be seen in other vaccines that use the same vaccine platform (inactive adenovirus). Cases have been reported mainly in patients younger than 60 years old and in unusual topographies. In particular, this case presents a male patient that is older than 60 years old, who had already been infected with COVID-19 five months before and who currently consults with thrombosis in regular sites. Therapeutic handling observed international guidelines. The case contributes relevant data both in terms of early diagnosis and therapeutic handling.


Resumo: Introdução: a vacinação contra a SARS-CoV-2 é uma ferramenta essencial na luta contra a pandemia de COVID-19. A vacina desenvolvida pela colaboração entre a Universidade de Oxford e o laboratório farmacêutico AstraZeneca (AZN) tem demonstrado boa eficácia, mas foram relatados casos de trombose venosa. Caso clínico: apresenta-se o caso de um paciente do sexo masculino, 70 anos, que 7 dias após a administração da primeira dose da vacina AZN desenvolveu trombose venosa profunda de ambos os membros inferiores e tromboembolismo pulmonar. Coincide com trombocitopenia de 15.000 / mm3, diminuição do fibrinogênio e aumento dos D-dímeros. A situação clínica lembra a trombocitopenia trombótica induzida por vacina (VITT). O tratamento foi realizado com imunoglobulinas intravenosas, metilprednisolona e crioprecipitados. Foi necessário colocar um filtro de veia cava inferior. Uma vez que a contagem de plaquetas melhorou, o tratamento anticoagulante com apixaban foi instalado. O paciente favoravelmente. Discussão: este é o primeiro relatório nacional de VITT. As tromboses subseqüentes à vacina AZN podem ser vistas com vacinas que compartilham a mesma plataforma (adenovírus inativado). Os casos foram relatados principalmente em pessoas com menos de 60 anos de idade e em topografias incomuns. Este caso tem a particularidade de se tratar de um paciente com mais de 60 anos, já com COVID-19 há cinco meses e que apresenta trombose em sítios comuns. O manejo terapêutico foi adaptado às diretrizes internacionais. O caso deixa um aprendizado relevante tanto no que diz respeito ao diagnóstico precoce quanto ao manejo terapêutico.


Subject(s)
Humans , Male , Aged , Pulmonary Embolism/therapy , Thrombocytopenia/therapy , Venous Thrombosis/therapy , COVID-19 Vaccines/adverse effects
13.
J Leukoc Biol ; 111(3): 725-734, 2022 03.
Article in English | MEDLINE | ID: covidwho-1380391

ABSTRACT

Following on from the devastating spread of COVID-19, a major global priority has been the production, procurement, and distribution of effective vaccines to ensure that the global pandemic reaches an end. However, concerns were raised about worrying side effects, particularly the occurrence of thrombosis and thrombocytopenia after administration of the Oxford/AstraZeneca and Johnson & Johnson's Janssen COVID-19 vaccine, in a phenomenon being termed vaccine-induced thrombotic thrombocytopenia (VITT). Similar to heparin-induced thrombocytopenia (HIT), this condition has been associated with the development of anti-platelet factor 4 antibodies, purportedly leading to neutrophil-platelet aggregate formation. Although thrombosis has also been a common association with COVID-19, the precise molecular mechanisms governing its occurrence are yet to be established. Recently, increasing evidence highlights the NLRP3 (NOD-like, leucine-rich repeat domains, and pyrin domain-containing protein) inflammasome complex along with IL-1ß and effete neutrophils producing neutrophil extracellular traps (NETs) through NETosis. Herein, we propose and discuss that perhaps the incidence of VITT may be due to inflammatory reactions mediated via IL-1ß/NLRP3 inflammasome activation and consequent overproduction of NETs, where similar autoimmune mechanisms are observed in HIT. We also discuss avenues by which such modalities could be treated to prevent the occurrence of adverse events and ensure vaccine rollouts remain safe and on target to end the current pandemic.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Extracellular Traps/immunology , Thrombocytopenia/etiology , Animals , COVID-19/immunology , COVID-19 Vaccines/therapeutic use , Humans , Inflammasomes/immunology , Interleukin-1beta/immunology , NLR Family, Pyrin Domain-Containing 3 Protein/immunology , Thrombocytopenia/immunology , Thrombocytopenia/prevention & control , Thrombocytopenia/therapy
14.
Molecules ; 26(16)2021 Aug 18.
Article in English | MEDLINE | ID: covidwho-1360793

ABSTRACT

The thrombotic thrombocytopenia syndrome (TTS), a complication of COVID-19 vaccines, involves thrombosis (often cerebral venous sinus thrombosis) and thrombocytopenia with occasional pulmonary embolism and arterial ischemia. TTS appears to mostly affect females aged between 20 and 50 years old, with no predisposing risk factors conclusively identified so far. Cases are characterized by thrombocytopenia, higher levels of D-dimers than commonly observed in venous thromboembolic events, inexplicably low fibrinogen levels and worsening thrombosis. Hyper fibrinolysis associated with bleeding can also occur. Antibodies that bind platelet factor 4, similar to those associated with heparin-induced thrombocytopenia, have also been identified but in the absence of patient exposure to heparin treatment. A number of countries have now suspended the use of adenovirus-vectored vaccines for younger individuals. The prevailing opinion of most experts is that the risk of developing COVID-19 disease, including thrombosis, far exceeds the extremely low risk of TTS associated with highly efficacious vaccines. Mass vaccination should continue but with caution. Vaccines that are more likely to cause TTS (e.g., Vaxzevria manufactured by AstraZeneca) should be avoided in younger patients for whom an alternative vaccine is available.


Subject(s)
COVID-19 Vaccines/adverse effects , Thrombocytopenia/chemically induced , Thrombocytopenia/therapy , Thrombosis/chemically induced , Thrombosis/therapy , Antibodies/blood , Diagnosis, Differential , Heparin/adverse effects , Humans , Platelet Factor 4/blood , Thrombocytopenia/etiology , Thrombosis/etiology
16.
Rinsho Shinkeigaku ; 61(9): 594-601, 2021 Sep 28.
Article in Japanese | MEDLINE | ID: covidwho-1344506

ABSTRACT

Vaccines are important in managing the COVID-19 pandemic caused by SARS-CoV-2. Despite the very low incidence, severe cases of thrombosis with thrombocytopenia after COVID-19 vaccination termed as Thrombosis with Thrombocytopenia Syndrome (TTS) have been reported. TTS clinically resembles autoimmune heparin-induced thrombocytopenia. TTS can cause disability and even death. It usually presents 4-28 days after vaccination characterized by thrombocytopenia and progressive thrombosis, often causing cerebral vein/venous thrombosis (CVT) and splanchnic venous thrombosis. We should avoid all forms of heparin and platelet transfusion. While awaiting further information on the pathophysiological mechanism and treatment of TTS, clinicians should be aware of TTS with CVT in patients receiving COVID-19 vaccinations. This new syndrome of TTS is an active area of investigation globally. Here, we review the available literature.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Cerebral Veins , Sinus Thrombosis, Intracranial/etiology , Thrombocytopenia/etiology , Adult , COVID-19/virology , Female , Humans , Immunoglobulins, Intravenous/administration & dosage , Male , Middle Aged , SARS-CoV-2 , Sinus Thrombosis, Intracranial/diagnosis , Sinus Thrombosis, Intracranial/epidemiology , Sinus Thrombosis, Intracranial/therapy , Syndrome , Thrombocytopenia/diagnosis , Thrombocytopenia/epidemiology , Thrombocytopenia/therapy , Time Factors
17.
JAMA ; 325(24): 2448-2456, 2021 06 22.
Article in English | MEDLINE | ID: covidwho-1318650

ABSTRACT

Importance: Cerebral venous sinus thrombosis (CVST) with thrombocytopenia, a rare and serious condition, has been described in Europe following receipt of the ChAdOx1 nCoV-19 vaccine (Oxford/AstraZeneca), which uses a chimpanzee adenoviral vector. A mechanism similar to autoimmune heparin-induced thrombocytopenia (HIT) has been proposed. In the US, the Ad26.COV2.S COVID-19 vaccine (Janssen/Johnson & Johnson), which uses a human adenoviral vector, received Emergency Use Authorization (EUA) on February 27, 2021. By April 12, 2021, approximately 7 million Ad26.COV2.S vaccine doses had been given in the US, and 6 cases of CVST with thrombocytopenia had been identified among the recipients, resulting in a temporary national pause in vaccination with this product on April 13, 2021. Objective: To describe reports of CVST with thrombocytopenia following Ad26.COV2.S vaccine receipt. Design, Setting, and Participants: Case series of 12 US patients with CVST and thrombocytopenia following use of Ad26.COV2.S vaccine under EUA reported to the Vaccine Adverse Event Reporting System (VAERS) from March 2 to April 21, 2021 (with follow-up reported through April 21, 2021). Exposures: Receipt of Ad26.COV2.S vaccine. Main Outcomes and Measures: Clinical course, imaging, laboratory tests, and outcomes after CVST diagnosis obtained from VAERS reports, medical record review, and discussion with clinicians. Results: Patients' ages ranged from 18 to younger than 60 years; all were White women, reported from 11 states. Seven patients had at least 1 CVST risk factor, including obesity (n = 6), hypothyroidism (n = 1), and oral contraceptive use (n = 1); none had documented prior heparin exposure. Time from Ad26.COV2.S vaccination to symptom onset ranged from 6 to 15 days. Eleven patients initially presented with headache; 1 patient initially presented with back pain and later developed headache. Of the 12 patients with CVST, 7 also had intracerebral hemorrhage; 8 had non-CVST thromboses. After diagnosis of CVST, 6 patients initially received heparin treatment. Platelet nadir ranged from 9 ×103/µL to 127 ×103/µL. All 11 patients tested for the heparin-platelet factor 4 HIT antibody by enzyme-linked immunosorbent assay (ELISA) screening had positive results. All patients were hospitalized (10 in an intensive care unit [ICU]). As of April 21, 2021, outcomes were death (n = 3), continued ICU care (n = 3), continued non-ICU hospitalization (n = 2), and discharged home (n = 4). Conclusions and Relevance: The initial 12 US cases of CVST with thrombocytopenia after Ad26.COV2.S vaccination represent serious events. This case series may inform clinical guidance as Ad26.COV2.S vaccination resumes in the US as well as investigations into the potential relationship between Ad26.COV2.S vaccine and CVST with thrombocytopenia.


Subject(s)
COVID-19 Vaccines/adverse effects , Sinus Thrombosis, Intracranial/etiology , Thrombocytopenia/etiology , Adolescent , Adult , Critical Care , Fatal Outcome , Female , Headache/etiology , Humans , Middle Aged , Platelet Count , Sinus Thrombosis, Intracranial/therapy , Thrombocytopenia/therapy
20.
N Engl J Med ; 385(8): 720-728, 2021 08 19.
Article in English | MEDLINE | ID: covidwho-1262030

ABSTRACT

The use of high-dose intravenous immune globulin (IVIG) plus anticoagulation is recommended for the treatment of vaccine-induced immune thrombotic thrombocytopenia (VITT), a rare side effect of adenoviral vector vaccines against coronavirus disease 2019 (Covid-19). We describe the response to IVIG therapy in three of the first patients in whom VITT was identified in Canada after the receipt of the ChAdOx1 nCoV-19 vaccine. The patients were between the ages of 63 and 72 years; one was female. At the time of this report, Canada had restricted the use of the ChAdOx1 nCoV-19 vaccine to persons who were 55 years of age or older on the basis of reports that VITT had occurred primarily in younger persons. Two of the patients in our study presented with limb-artery thrombosis; the third had cerebral venous and arterial thrombosis. Variable patterns of serum-induced platelet activation were observed in response to heparin and platelet factor 4 (PF4), indicating the heterogeneity of the manifestations of VITT in serum. After the initiation of IVIG, reduced antibody-induced platelet activation in serum was seen in all three patients. (Funded by the Canadian Institutes of Health Research.).


Subject(s)
COVID-19 Vaccines/adverse effects , Immunoglobulins, Intravenous , Thrombocytopenia/therapy , Thrombosis/therapy , Aged , Female , Fibrin Fibrinogen Degradation Products/analysis , Fibrinogen/analysis , Heparin/pharmacology , Humans , Male , Middle Aged , Platelet Count , Platelet Factor 4/pharmacology , Serotonin/blood , Thrombocytopenia/blood , Thrombocytopenia/etiology , Thrombosis/etiology , Thrombosis/immunology
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