Partial quantitative deficiency of plasma von Willebrand factor (VWF) is responsible for the majority of cases of von Willebrand disease (VWD), the most common inherited human bleeding disorder. ...International consensus guidelines recommend that patients with reduced plasma VWF antigen (VWF:Ag) levels and bleeding phenotypes be considered in 2 distinct subsets. First, patients with marked reductions in plasma VWF levels (<30 IU/dL) usually have significant bleeding phenotypes and should be classified with “type 1 VWD.” In contrast, patients with intermediate reduced plasma VWF levels (in the range of 30-50 IU/dL) should be considered in a separate category labeled “low VWF levels.” These patients with low VWF commonly display variable bleeding phenotypes and often do not have VWF gene sequence variations. Because the pathophysiology underlying low VWF levels remains largely undefined, diagnosis and management of these patients continue to pose significant difficulties. In this article, we present a number of clinical case studies to highlight these common clinical challenges. In addition, we detail our approach to establishing a diagnosis in low VWF patients and discuss strategies for the management of these patients in the context of elective surgery and pregnancy.
Summary
The mechanisms involved in regulating von Willebrand factor (VWF) clearance remain poorly understood. However recent studies have shown that macrophages play a critical role in regulating the ...half‐life of VWF, and have identified specific lectin (including asialoglycoprotein, macrophage galactose‐type lectin, Sigec‐5 and C‐type lectin domain family 4 member M) and scavenger receptors (including low‐density lipoprotein receptor‐related protein‐1, scavenger receptor A1 and stabilin‐2) that are involved in VWF clearance. Further studies will be required to determine the relative importance of these individual receptors with respect to physiological and pathological VWF clearance. Nevertheless, recent clinical data have highlighted the importance of enhanced VWF clearance in the pathogenesis of type 1 von Willebrand disease (VWD). Moreover, increased clearance also contributes to reduced VWF levels in many patients with type 2 and type 3 VWD. Improved understanding regarding VWF clearance is not only of direct biological relevance, but may also have important implications for the development of novel therapeutic agents with extended plasma half‐lives for the treatment of both VWD and haemophilia A.
Background
Consistent with fulminant endothelial cell activation, elevated plasma von Willebrand factor (VWF) antigen levels have been reported in patients with COVID‐19. The multimeric size and ...function of VWF are normally regulated through A Disintegrin And Metalloprotease with ThrombSpondin Motif type 1 motif, member 13 (ADAMTS‐13)‐‐mediated proteolysis.
Objectives
This study investigated the hypothesis that ADAMTS‐13 regulation of VWF multimer distribution may be impaired in severe acute respiratory syndrome‐coronavirus‐2 (SARS‐CoV‐2) infection contributing to the observed microvascular thrombosis.
Patients and Methods
Patients with COVID‐19 (n = 23) were recruited from the Beaumont Hospital Intensive Care Unit (ICU) in Dublin. Plasma VWF antigen, multimer distribution, ADAMTS‐13 activity, and known inhibitors thereof were assessed.
Results
We observed markedly increased VWF collagen‐binding activity in patients with severe COVID‐19 compared to controls (median 509.1 versus 94.3 IU/dl). Conversely, plasma ADAMTS‐13 activity was significantly reduced (median 68.2 IU/dl). In keeping with an increase in VWF:ADAMTS‐13 ratio, abnormalities in VWF multimer distribution were common in patients with COVID‐19, with reductions in high molecular weight VWF multimers. Terminal sialylation regulates VWF susceptibility to proteolysis by ADAMTS‐13 and other proteases. We observed that both N‐ and O‐linked sialylation were altered in severe COVID‐19. Furthermore, plasma levels of the ADAMTS‐13 inhibitors interleukin‐6, thrombospondin‐1, and platelet factor 4 were significantly elevated.
Conclusions
These findings support the hypothesis that SARS‐CoV‐2 is associated with profound quantitative and qualitative increases in plasma VWF levels, and a multifactorial down‐regulation in ADAMTS‐13 function. Further studies will be required to determine whether therapeutic interventions to correct ADAMTS‐13‐VWF multimer dysfunction may be useful in COVID‐microvascular thrombosis and angiopathy.
Multiple myeloma (MM) is associated with an increased risk of venous thrombosis (VTE). In the United Kingdom Medical Research Council (MRC) XI study of patients treated with immunomodulatory therapy, ...the VTE rate was 11.8% despite 87.7% of the patients being on thromboprophylaxis at the time of thrombosis. In order to effectively prevent VTE events in MM patients, a better understanding of patient and disease risk factors that might predict thrombosis is required. We performed a retrospective cohort analysis of over 300 newly diagnosed MM patients at a tertiary referral centre to determine the VTE rate, predictive factors for VTE, value of the Khorana score for MM VTE events and long-term mortality outcomes. Fifty-four percent of the patients were receiving thromboprophylaxis at the time of the VTE event. The mortality odds ratio was 3.3 (95% CI, 2.4–4.5) in patients who developed VTE in comparison to age-matched controls with MM. A younger age at diagnosis and higher white cell count (WCC) were found to be predictive of VTE events. Our data suggest that standard thromboprophylaxis may not be effective in preventing VTE events in myeloma patients, and alternative strategies, which could include higher-intensity thromboprophylaxis in young patients with a high WCC, are necessary.
•Subtle enhanced VWF clearance is present in 20% of patients with low VWF and is associated with an attenuated bleeding phenotype.•In patients with low VWF, there is poor correlation between ...desmopressin fall-off rates and steady-state VWFpp/VWF:Ag ratios.
Increased von Willebrand factor (VWF) clearance plays a key role in the pathogenesis of type 1 and type 2 von Willebrand disease (VWD). However, the pathological mechanisms involved in patients with mild to moderate reductions in plasma VWF:Ag (range, 30-50 IU/dL; low VWF) remain poorly understood. In this study, we investigated the hypothesis that enhanced VWF clearance may contribute to the pathobiology of low VWF. Patients with low VWF were recruited to the LoVIC study after ethics approval and receipt of informed consent. Desmopressin was administered IV in 75 patients, and blood samples were drawn at baseline and at the 1-hour and 4-hour time points. As defined by recent ASH/ISTH/NHF/WFH guidelines, 20% of our low-VWF cohort demonstrated significantly enhanced VWF clearance. Importantly, from a clinical perspective, this enhanced VWF clearance was seen after desmopressin infusion, but did not affect the steady-state VWF propeptide (VWFpp)-to-VWF antigen (VWF:Ag) ratio (VWFpp/VWF:Ag) in most cases. The discrepancy between the VWFpp/VWF:Ag ratio and desmopressin fall-off rates in patients with mild quantitative VWD may have reflected alteration in VWFpp clearance kinetics. Finally, bleeding scores were significantly lower in patients with low VWF with enhanced VWF clearance, compared with those in whom reduced VWF biosynthesis represented the principle pathogenic mechanism. This trial was registered at http://www.clinicaltrials.gov as #NCT03167320.
Despite the increased worldwide awareness, over the last decade, of the platelet-type von Willebrand Disease (PT-VWD), many uncertainties remain around this rare platelet bleeding disorder. This ...report aims to correctly identify and study the phenotype of new patients and highlights the diagnostic and therapeutic challenges this disease remains to pose. We describe four PT-VWD cases confirmed by genetic analysis in which either the diagnosis and/or the treatment posed challenge. We provide the details of the clinical presentation, laboratory analysis, and the treatment and the responses in each case. We show that in addition to type 2B VWD, PT-VWD can be misdiagnosed as idiopathic thrombocytopenic purpura, neonatal alloimmune thrombocytopenia, and unexplained gestational thrombocytopenia. The disease can be diagnosed as early as 1 year of age and with phenotypically normal parents. Bleeding in some patients can be managed successfully using Humate P and DDAVP combined with tranexamic acid with no significant thrombocytopenia. We provide for the first time an evidence of an efficient response to rFVIIa in PT-VWD. Anaphylactic reaction to VWF preparations may be related to PT-VWD and the development of HLA antibodies is not uncommon. Progressive thrombocytopenia with normal VWF levels can be seen with PT-VWD and the platelet count was normalized at 2.5 weeks postpartum in one case. We conclude that these studies represent a record of clinical observations/interventions that help improve diagnoses/management of PT-VWD, highlight the variations in age and clinical presentations, laboratory diagnostic approaches, the importance of genetic testing for accurate diagnosis and consideration of therapeutic alternatives.
The 2022 World Federation of Haemophilia Annual Global Survey (AGS) reports that 454,690 patients with inherited bleeding disorders (IBD) have been identified globally. While this represents ...noteworthy progress, haemophilia epidemiology data indicate that 75% of people with inherited bleeding disorders living in low‐income and low‐to‐middle‐income countries have yet to be diagnosed. The AGS also revealed that 11 billion clotting factor units are available to treat haemophilia A and B globally. Due to a lack of finance, these treatments are unavailable to haemophilia in low‐income countries with a consequence lack of access equity for haemophilia treatment in these communities. This sobering reality is not limited to haemophilia but applies to von Willebrand Disease (VWD). While VWD is the most prevalent IBD, only 103,844 people living with this condition have been diagnosed globally. Of the diagnosed patients, only a fraction live in low‐ or middle‐income countries. Moreover, the majority of VWD patients are still treated sub‐optimally without replacement therapies or prophylaxis, both of which are now accepted as global standards of care. In this state‐of‐the‐art review, the authors reflect on three issues. First, the minimum elements required to diagnose haemophilia in a resource‐constrained setting are identified. Second, this review points to the critical stakeholders and outlines their roles in removing access to haemophilia treatment barriers. Finally, the authors examine von Willebrand disease's ongoing diagnostic and treatment challenges and compare these to haemophilia. With the rapidly evolving novel therapies, the therapeutic landscape of all IBD will likely change for the better.
Background
Early evidence of COVID-19–associated coagulopathy disseminated rapidly online during the first months of 2020, followed by clinical debate about how best to manage thrombotic risks in ...these patients. The rapid online spread of case reports was followed by online interim guidelines, discussions, and worldwide online searches for further information. The impact of global online search trends and online discussion on local approaches to coagulopathy in patients with COVID-19 has not been studied.
Objective
The goal of this study was to investigate the relationship between online search trends using Google Trends and the rate of appropriate venous thromboembolism (VTE) prophylaxis and anticoagulation therapy in a cohort of patients with COVID-19 admitted to a tertiary hospital in Ireland.
Methods
A retrospective audit of anticoagulation therapy and VTE prophylaxis among patients with COVID-19 who were admitted to a tertiary hospital was conducted between February 29 and May 31, 2020. Worldwide Google search trends of the term “COVID-19” and anticoagulation synonyms during this time period were determined and correlated against one another using a Spearman correlation. A P value of <.05 was considered significant, and analysis was completed using Prism, version 8 (GraphPad).
Results
A statistically significant Spearman correlation (P<.001, r=0.71) was found between the two data sets, showing an increase in VTE prophylaxis in patients with COVID-19 with increasing online searches worldwide. This represents a proxy for online searches and discussion, dissemination of information, and Google search trends relating to COVID-19 and clotting risk, in particular, which correlated with an increasing trend of providing thromboprophylaxis and anticoagulation therapy to patients with COVID-19 in our tertiary center.
Conclusions
We described a correlation of local change in clinical practice with worldwide online dialogue and digital search trends that influenced individual clinicians, prior to the publication of formal guidelines or a local quality-improvement intervention.
As a result of the coronavirus disease 2019 pandemic, the International Society on Thrombosis and Haemostasis (ISTH), like many societies around the world, canceled their in‐person hematology ...congress planned for Milan, Italy, in July 2020. As a result, the first virtual ISTH congress in the organisation’s 51‐year history was delivered, inviting free registration from across the globe. As part of the social media support, marketing, and scientific dissemination efforts for the virtual congress, the ISTH assembled a group of official Twitter Ambassadors, which represented the broad and diverse ISTH community. Ambassadors were tasked to tweet daily throughout the congress and to share their commentary on the hematology research being presented with the “#ISTH2020” hashtag. Ambassadors were also supported by Twitter activities from the two official ISTH‐affiliated journals: the Journal of Thrombosis and Haemostasis (JTH) and Research and Practice in Thrombosis and Haemostasis (RPTH). In this forum and through the Twitter ambassadors’ lens, we present the Twitter Ambassadors’ experience, reflect on the impact of social media on the ISTH 2020 congress, and share this experience with the wider scientific community. Specifically, we report on the role of Twitter communication for virtual meetings, discuss the pros and cons of the virtual congress, and offer Twitter‐related recommendations for future virtual or blended congresses. We conclude that the ISTH Twitter Ambassador program broadened social media engagement and offers a novel route to improve social connectivity in the virtual research congress setting.
Illustrated State‐of‐the‐Art Capsules of the ISTH 2021 Congress Krishnaswamy, Sriram; Ageno, Walter; Arabi, Yaseen ...
Research and practice in thrombosis and haemostasis,
July 2021, 2021-07-00, 20210701, 2021-07-01, Letnik:
5, Številka:
5
Journal Article
Recenzirano
Odprti dostop
This year's Congress of the International Society of Thrombosis and Haemostasis (ISTH) was hosted virtually from Philadelphia July 17–21, 2021. The conference, now held annually, highlighted ...cutting‐edge advances in basic, population and clinical sciences of relevance to the Society. Despite being held virtually, the 2021 congress was of the same scope and quality as an annual meeting held in person. An added feature of the program is that talks streamed at the designated times will then be available on‐line for asynchronous viewing. The program included 77 State of the Art (SOA) talks, thematically grouped in 28 sessions, given by internationally recognized leaders in the field. The SOA speakers were invited to prepare brief illustrated reviews of their talks that were peer reviewed and are included in this article. The topics, across the main scientific themes of the congress, include Arterial Thromboembolism, Coagulation and Natural Anticoagulants, COVID‐19 and Coagulation, Diagnostics and Omics, Fibrinogen, Fibrinolysis and Proteolysis, Hemophilia and Rare Bleeding Disorders, Hemostasis in Cancer, Inflammation and Immunity, Pediatrics, Platelet Disorders, von Willebrand Disease and Thrombotic Angiopathies, Platelets and Megakaryocytes, Vascular Biology, Venous Thromboembolism and Women's Health. These illustrated capsules highlight the major scientific advances with potential to impact clinical practice. Readers are invited to take advantage of the excellent educational resource provided by these illustrated capsules. They are also encouraged to use the image in social media to draw attention to the high quality and impact of the science presented at the congress.
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