Heparin-induced thrombocytopenia (an overview)

A systematic review of vaccine-induced thrombotic thrombocytopenia in individuals who received COVID-19 adenoviral-vector-based vaccines

Reports of thrombotic response after receiving COVID-19 Adenoviral-Vector Based Vaccines raise concerns about vaccine-induced thrombotic thrombocytopenia (VITT); therefore, we conduct this systematic review to report susceptible demographics outcomes, commonalities, and prognosis of reporting cases. We identified published articles by searching PubMed, SCOPUS, and Web of Science from December 2020 till May 2021, with an updated search in September 2021. All case reports and case series reporting thrombotic response after receiving COVID-19 Adenoviral-Vector Based Vaccines were eligible for including. In addition, two authors independently extracted data and assessed the quality of the included studies. A total of 157 patients with thrombotic events after the ChAdOx1 nCoV-19 vaccine and 16 patients with thrombotic events after Ad26.COV2. S vaccine was included in our study. 72% of the ChAdOx1 nCoV-19 cases were females, while in Ad26.COV2.S subgroup, all reported patients were females. The commonest presentations were deep vein thrombosis 20 (12.7%) and cerebral venous sinus thrombosis 18 (11.5%) in the ChAdOx1 nCoV-19 subgroup while cerebral venous sinus thrombosis 14 (87.5%) and pulmonary embolism 2 (12.5%) in the Ad26.COV2. S subgroup. In this study, we described the certain demographics associated with VITT and the clinical presentations of those cases in the ChAdOx1 nCoV-19 and Ad26.COV2. S vaccines. Young individuals, particularly females, may be more susceptible to VITT, and future studies should seek to confirm this association. In addition, the clinical presentation of VITT commonly includes cerebral thrombi, pulmonary embolism, and deep venous thrombosis, but other presentations are also possible, highlighting the importance of clinical vigilance in recent vaccine recipients.

Prognostic factors for patients with heparin-induced thrombocytopenia: a systematic review

Background  Little is known with regards to the prognostic factors for patients with suspected or diagnosed Heparin-Induced Thromobocytopenia (HIT). The role of patient and therapy characteristics may play a role in predicting the outcome. Aim of the review To investigate the role of patient and therapy characteristics as potential prognostic factors for HIT-related complications (haemorrhagic and thromboembolic events), and mortality. Method The present systematic review was conducted according to the PRISMA statement. In September 2020, the main online databases were accessed: Pubmed, EMBASE, Scopus, Google Scholar. All the clinical trials concerning the management of patients with suspected or confirmed HIT were eligible. Studies evaluating the use of oral anticoagulants (e.g. vitamin K antagonists, Apixaban) were not considered, along with those comparing the use of heparin. For pairwise correlation, the Pearson Product-Moment Correlation Coefficient (r) was used. The final effect was evaluated according to the Cauchy-Schwarz inequality.Results Data from 33 clinical studies (4338 patients) were retrieved. The overall mean age was 62.3 ± 6.6 years old. Patients with HIT-related thromboembolism at the moment of diagnosis were associated with greater rate of haemorrhages (P > 0.0001), thromboembolism (P > 0.0001) and mortality (P = 0.001). Patients with more comorbidities at diagnosis were associated with a greater risk of haemorrhages (P = 0.07), thromboembolism (P = 0.002) and mortality (P = 0.002). Patients with longer duration of the therapy were associated with lower rate of mortality (P = 0.04). ConclusionsPatient comorbidities, presence of HIT-related thromboembolism on admission and shorter anticoagulant therapy were found to be negative prognostic factors. Thrombocythemia on admission, patients age and gender did not influence the overall outcome.

Trombocitopenia induzida por heparina em paciente com oclusão arterial aguda

Resumo A trombocitopenia induzida por heparina é uma complicação grave da terapêutica anticoagulante com heparina e está associada à formação de anticorpos antifator IV plaquetário. Costuma surgir a partir do quinto dia do tratamento, com queda de pelo menos 50% da contagem plaquetária. Em decorrência da ativação plaquetária concomitante, pode ocorrer quadro de trombose, venosa ou arterial, com repercussões clínicas graves. Apresentamos um caso de paciente portador de síndrome do anticorpo antifosfolípide, com quadro de oclusão arterial aguda, que foi tratado cirurgicamente e recebeu heparina não fracionada no intra e pós-operatório. No quinto dia de tratamento anticoagulante, apresentou queda maior de 50% da contagem de plaquetas em relação à contagem pré-heparina. A suspeita de trombocitopenia induzida por heparina e seus aspectos diagnósticos e terapêuticos serão abordados neste desafio terapêutico.

Low-dose intravenous heparin infusion in patients with aneurysmal subarachnoid hemorrhage: a preliminary assessment

OBJECT

Aneurysmal subarachnoid hemorrhage (aSAH) predisposes to delayed neurological deficits, including stroke and cognitive and neuropsychological abnormalities. Heparin is a pleiotropic drug that antagonizes many of the pathophysiological mechanisms implicated in secondary brain injury after aSAH.

METHODS

The authors performed a retrospective analysis in 86 consecutive patients with Fisher Grade 3 aSAH due to rupture of a supratentorial aneurysm who presented within 36 hours and were treated by surgical clipping within 48 hours of their ictus. Forty-three patients were managed postoperatively with a low-dose intravenous heparin infusion (Maryland low-dose intravenous heparin infusion protocol: 8 U/kg/hr progressing over 36 hours to 10 U/kg/hr) beginning 12 hours after surgery and continuing until Day 14 after the ictus. Forty-three control patients received conventional subcutaneous heparin twice daily as deep vein thrombosis prophylaxis.

RESULTS

Patients in the 2 groups were balanced in terms of baseline characteristics. In the heparin group, activated partial thromboplastin times were normal to mildly elevated; no clinically significant hemorrhages or instances of heparin-induced thrombocytopenia or deep vein thrombosis were encountered. In the control group, the incidence of clinical vasospasm requiring rescue therapy (induced hypertension, selective intraarterial verapamil, and angioplasty) was 20 (47%) of 43 patients, and 9 (21%) of 43 patients experienced a delayed infarct on CT scanning. In the heparin group, the incidence of clinical vasospasm requiring rescue therapy was 9% (4 of 43, p = 0.0002), and no patient suffered a delayed infarct (p = 0.003).

CONCLUSIONS

In patients with Fisher Grade 3 aSAH whose aneurysm is secured, postprocedure use of a low-dose intravenous heparin infusion may be safe and beneficial.

Heparin-induced thrombocytopenia in the pediatric population: a review of current literature

Heparin-induced thrombocytopenia is a rare and serious reaction to unfractionated heparin and low-molecular-weight heparins in children. Quick recognition, discontinuation of heparin, and subsequent treatment with an alternative anticoagulant are essential steps to prevent serious complications such as thrombus and limb amputation. The purpose of this review is to describe the clinical features of heparin-induced thrombocytopenia in children and to summarize the data available for its management. This paper summarizes data and relates the use of direct thrombin inhibitors with clinical outcomes. A literature search was conducted with Ovid, using the key terms argatroban, bivalirudin, hirulog, danaparoid, lepirudin, direct thrombin inhibitor, heparin-induced thrombocytopenia, thrombosis, warfarin, and fondaparinux. Articles were excluded if they were classified as editorials, review articles, or conference abstracts or if they involved patients 18 years of age or older or described disease states not related to thrombosis. Nineteen articles containing 33 case reports were identified and evaluated for this review. Of the 33 cases, 14, 10, 4, and 2 cases described the use of lepirudin, danaparoid, argatroban, and bivalirudin, respectively. Two cases did not report the type of anticoagulant used, and 1 case used aspirin. The most commonly reported complication was bleeding.

Thrombocytopenia after total knee arthroplasty

Heparin-induced thrombocytopenia is a serious complication during antithromboembolic prophylaxis caused by anti-heparin/platelet factor 4 (PF4) complex antibodies. It typically arises 3 to 15 days after the beginning of therapy and may result in an increased risk of arterial and venous thromboembolism. This article presents a case of thrombocytopenia associated with vein thrombosis in a man who underwent a total knee arthroplasty (TKA).

Serpins in thrombosis, hemostasis and fibrinolysis

Hemostasis and fibrinolysis, the biological processes that maintain proper blood flow, are the consequence of a complex series of cascading enzymatic reactions. Serine proteases involved in these processes are regulated by feedback loops, local cofactor molecules, and serine protease inhibitors (serpins). The delicate balance between proteolytic and inhibitory reactions in hemostasis and fibrinolysis, described by the coagulation, protein C and fibrinolytic pathways, can be disrupted, resulting in the pathological conditions of thrombosis or abnormal bleeding. Medicine capitalizes on the importance of serpins, using therapeutics to manipulate the serpin-protease reactions for the treatment and prevention of thrombosis and hemorrhage. Therefore, investigation of serpins, their cofactors, and their structure-function relationships is imperative for the development of state-of-the-art pharmaceuticals for the selective fine-tuning of hemostasis and fibrinolysis. This review describes key serpins important in the regulation of these pathways: antithrombin, heparin cofactor II, protein Z-dependent protease inhibitor, alpha(1)-protease inhibitor, protein C inhibitor, alpha(2)-antiplasmin and plasminogen activator inhibitor-1. We focus on the biological function, the important structural elements, their known non-hemostatic roles, the pathologies related to deficiencies or dysfunction, and the therapeutic roles of specific serpins.

[Skin and mucosal ulcerations in heparin-induced thrombocytopenia (HIT) II]

About 0.1-2% of patients receiving heparin develop heparin-induced thrombocytopenia type II (HIT II) which is caused by antibodies directed against heparin-platelet factor 4 (PF4) complexes. Activation of thrombocytes and endothelial cells can lead to thrombocytopenia, venous and arterial thrombosis or thromboembolic events 10-14 days after the first dose. HIT II has a high mortality rate because of pulmonary emboli, cerebrovascular accidents, myocardial and limb infarctions. A 55-year-old patient with HIT II presented with arterial and venous thromboses and a silent myocardial infarction. In addition, he showed extensive skin and mucosal necrosis, an uncommon complication. Rheologic therapy with danaparoid Natrium, alprostadil alfadex and acetylsalicylic acid in combination with percutaneous transluminal angioplasties as well as local and systemic antiinflammatory therapy prevented further progression of the disease.