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Warkentin TE. A career in solving clinical-pathological conundrums: Heyde syndrome, anti-platelet factor 4 disorders, and microvascular limb ischemic necrosis. Int J Lab Hematol 2024; 46 Suppl 1:12-26. [PMID: 38432651 DOI: 10.1111/ijlh.14261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 02/14/2024] [Indexed: 03/05/2024]
Abstract
Hematology is a clinical specialty with strong roots in the laboratory; accordingly, the lab can help solve perplexing clinical problems. This review highlights clinical-pathological conundrums addressed during my 35-year hematology career at McMaster University. Heyde syndrome is the association between aortic stenosis and bleeding gastrointestinal (GI) angiodysplasia where the bleeding is usually cured by aortic valve replacement; the chance reading of a neonatal study showing reversible deficiency of high-molecular-weight (HMW) multimers of von Willebrand factor (vWF) following surgical correction of congenital heart disease provided the key insight that a subtle deficiency of HMW multimers of vWF explains Heyde syndrome. The unusual immunobiology of heparin-induced thrombocytopenia (HIT)-a highly prothrombotic, antibody-mediated, anti-platelet factor 4 (PF4) disorder featuring rapid appearance and then disappearance (seroreversion) of the pathological heparin-dependent platelet-activating antibodies-permitted identification of key clinical features that informed development of a scoring system (4Ts) to aid in HIT diagnosis. Atypical clinical presentations of HIT prompted identification of heparin-independent anti-PF4 antibodies, now recognized as the explanation for vaccine-induced immune thrombotic thrombocytopenia (VITT), as well as VITT-like disorders triggered by adenovirus infection. Another unusual feature of HIT is its strong association with limb ischemia, including limb necrosis secondary to deep-vein/microvascular thrombosis (venous limb gangrene). The remarkable observation that supratherapeutic warfarin anticoagulation predisposes to HIT- and cancer-associated venous limb gangrene provided insight into disturbed procoagulant/anticoagulant balance; these concepts are relevant to microvascular thrombosis in critical illness (symmetrical peripheral gangrene), including a pathophysiological role for proximate "shock liver" (impaired hepatic synthesis of natural anticoagulants).
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, and Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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2
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Giles JB, Rollin J, Martinez KL, Selleng K, Thiele T, Pouplard C, Sheppard JAI, Heddle NM, Phillips EJ, Roden DM, Gruel Y, Warkentin TE, Greinacher A, Karnes JH. Laboratory and demographic predictors of functional assay positive status in suspected heparin-induced thrombocytopenia: A multicenter retrospective cohort study. Thromb Res 2023; 229:198-208. [PMID: 37541168 PMCID: PMC10528503 DOI: 10.1016/j.thromres.2023.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/16/2023] [Accepted: 07/18/2023] [Indexed: 08/06/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against platelet factor 4 (PF4) bound to heparin anticoagulants. A priori identification of patients at-risk for HIT remains elusive and a number of risk factors have been identified, but these associations and their effect sizes have limited validation in large cohorts of suspected HIT patients. The aim of this study was to investigate existing anti-PF4/heparin antibody thresholds and model the relationship of demographic variables and anti-PF4/heparin antibody levels with functional assay positivity across multiple institutions in the absence of detailed clinical data. In a large collection of suspected HIT patients (n = 8904), we tested for associations between laboratory and demographic variables and functional assay positive status as well as anti-PF4/heparin antibody levels. We also tested for correlation between IgG-specific and polyspecific (IgG/IgA/IgM) anti-PF4/heparin antibody values and their ability to predict functional assay positive status using area under the receiver operating characteristic (AUROC). Logistic regression identified increasing anti-PF4/heparin antibody OD levels (OR = 51.84 [37.27-74.34], p < 2.0 × 10-16) and female sex (OR = 1.47 [1.19-1.82], p = 3.5 × 10-4) as risk factors for positive functional assay in the largest cohort with consistent effect sizes in two other cohorts. In a subset of 1175 patients, polyspecific and IgG-specific anti-PF4/heparin antibody values were heterogeneous (mean coefficient of variation = 31.9 %), but strongly correlated (rho = 0.878; p < 2 × 10-16) with similar prediction of functional assay positivity (polyspecific AUROC = 0.976 and IgG-specific AUROC = 0.980). Thus, we recapitulate previously identified risk factors of functional assay positivity, providing precise effect sizes in a large observational population of suspected HIT patients. Our data reinforce the necessity of functional assay confirmation and suggest that, despite heterogeneity, polyspecific and IgG-specific anti-PF4/heparin antibody assays predict functional assay positive status similarly, even in the absence of 4Ts scores and detailed clinical data.
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Affiliation(s)
- Jason B Giles
- Department of Pharmacy Practice and Science, University of Arizona R. Ken Coit College of Pharmacy, Tucson, AZ, USA
| | - Jerome Rollin
- Regional University Hospital Centre Tours, Department of Hemostasis, Tours, France; University of Tours, EA4245, T2i, Tours, France
| | - Kiana L Martinez
- Department of Pharmacy Practice and Science, University of Arizona R. Ken Coit College of Pharmacy, Tucson, AZ, USA
| | - Kathleen Selleng
- Institute of Immunology and Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Thomas Thiele
- Institute of Immunology and Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Claire Pouplard
- Regional University Hospital Centre Tours, Department of Hemostasis, Tours, France; University of Tours, EA4245, T2i, Tours, France
| | - Jo-Ann I Sheppard
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Nancy M Heddle
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Elizabeth J Phillips
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Yves Gruel
- Regional University Hospital Centre Tours, Department of Hemostasis, Tours, France; University of Tours, EA4245, T2i, Tours, France
| | - Theodore E Warkentin
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Andreas Greinacher
- Institute of Immunology and Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Jason H Karnes
- Department of Pharmacy Practice and Science, University of Arizona R. Ken Coit College of Pharmacy, Tucson, AZ, USA; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA.
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Warkentin TE, Greinacher A. Laboratory Testing for Heparin-Induced Thrombocytopenia and Vaccine-Induced Immune Thrombotic Thrombocytopenia Antibodies: A Narrative Review. Semin Thromb Hemost 2023; 49:621-633. [PMID: 36455619 PMCID: PMC10421650 DOI: 10.1055/s-0042-1758818] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT) are highly prothrombotic (thrombosis frequency ≥50%). Both are caused by platelet-activating anti-platelet factor 4 (PF4) antibodies, forming PF4/IgG-containing immune complexes that engage platelet FcγIIa receptors, producing strong platelet activation. In HIT, heparin crosslinks several PF4 molecules, whereas in VITT, anti-PF4 antibodies alone crosslink PF4. Sufficient levels of circulating anti-PF4 antibodies are needed to create the pathogenic immune complexes on platelet surfaces; this explains why certain serum (plasma)-based assays are highly sensitive for detecting HIT/VITT antibodies. Accordingly, HIT and VITT are "clinical-pathological" disorders, that is, positive testing for such antibodies-together with a compatible clinical picture-is integral for diagnosis. Heparin (low concentrations) enhances HIT antibody-induced platelet activation, but platelet activation by VITT sera is usually inhibited by heparin. For both HIT and VITT, high sensitivity (>99% and >95%, respectively) characterizes PF4-dependent enzyme immunoassays (EIAs) and PF4-enhanced platelet activation assays; in contrast, certain rapid immunoassays have high sensitivity for HIT (>90-97%) but poor sensitivity (<25%) for VITT. HIT and VITT antibodies are directed at distinct sites on PF4: solid-phase EIAs and platelet activation assays are indifferent to these distinct antigen targets, but rapid immunoassays are not. We discuss a conceptual model where PF4 is viewed as a "globe," with the heparin-binding site the "equator"; in this model, HIT antibodies are primarily directed at antigen site(s) at the north and south "poles" of PF4 (formed when PF4 binds to heparin), whereas VITT antibodies recognize sites on the equator.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada
- Service of Benign Hematology, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada
| | - Andreas Greinacher
- Institute for Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
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May J, Westbrook B, Cuker A. Heparin-induced thrombocytopenia: An illustrated review. Res Pract Thromb Haemost 2023; 7:100283. [PMID: 37601013 PMCID: PMC10439402 DOI: 10.1016/j.rpth.2023.100283] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 08/22/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug effect from unfractionated or low-molecular-weight heparin that results in thrombocytopenia and potentially catastrophic thrombosis. HIT occurs due to the development of platelet-activating antibodies against multimolecular complexes of platelet factor 4 and heparin. Given the frequency of thrombocytopenia and heparin use among hospitalized patients, calculation of the 4Ts Score is recommended to identify patients at increased likelihood of HIT and direct further evaluation. In patients with an intermediate or high probability 4Ts Score, an immunoassay and functional assay are recommended to confirm or refute the diagnosis of HIT. Heparin avoidance and initiation of nonheparin anticoagulation are the mainstays of acute HIT management. In this illustrated review, we provide visual summaries of the diagnosis and management of HIT, highlighting connections between pathophysiology and clinical care as well as summarizing efforts in quality improvement in the field. We further emphasize common pitfalls and pearls in diagnosis and management to encourage evidence-based care. We include graphical representation of the unique challenges of HIT with cardiopulmonary bypass and also delineate autoimmune HIT and its subtypes.
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Affiliation(s)
- Jori May
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Brian Westbrook
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Adam Cuker
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Silva FD, Burnett AE, Padmanabhan A, Rollins-Raval MA, Splinter NP, Desai MJ. Cerebral venous sinus thrombosis associated with SRA-negative heparin-induced thrombocytopenia: case report. Thromb J 2023; 21:46. [PMID: 37085884 PMCID: PMC10122294 DOI: 10.1186/s12959-023-00490-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 04/12/2023] [Indexed: 04/23/2023] Open
Abstract
BACKGROUND There are very few documented reports in literature of cerebral venous sinus thrombosis (CVST) caused by immune-mediated heparin-induced thrombocytopenia (HIT). Further, there are very few reports of false negative serotonin release assays (SRAs) when testing for immune-mediated HIT. CASE PRESENTATION We present a case of a 60- year-old male with recent unfractionated heparin administration for venous thromboembolism prophylaxis, an elevated 4T score of 5 and acute CVST in which immune-mediated HIT was suspected. The enzyme-linked immunosorbent assay (ELISA) screening assay was positive for PF4 antibodies and subsequent reflexive SRA testing was negative. However, given the clinical picture, a false-negative SRA was suspected (and eventually confirmed), prompting use of the alternative PF4-dependent p-selectin expression assay (PEA) which was confirmed to be positive. The patient was successfully managed with a bivalirudin infusion and eventually transitioned to apixaban. CONCLUSION It is uncommon for immune-mediated HIT with thrombosis to manifest as CVST. Similarly, false-negative SRA is uncommon in immune-mediated HIT. Take-away lessons from our case report include considering HIT in CVST patients with an elevated 4T score and considering the entire clinical picture and degree of suspicion for HIT when interpreting negative HIT testing results. The PEA, in conjunction with the 4Ts score, may be considered as an alternate diagnostic assay for HIT.
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Affiliation(s)
- Floyd D Silva
- University of New Mexico School of Medicine, Albuquerque, NM, USA
| | | | - Anand Padmanabhan
- Division of Experimental Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Marian A Rollins-Raval
- University of New Mexico School of Medicine, Albuquerque, NM, USA
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Noah P Splinter
- Division of Experimental Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Masoom J Desai
- University of New Mexico School of Medicine, Albuquerque, NM, USA.
- Department of Neurology, University of New Mexico School of Medicine, Albuquerque, NM, USA.
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Duerson WA, Lopes CE, Dumani DA. Self-limited thrombotic thrombocytopenic purpura. Blood Coagul Fibrinolysis 2023; 34:218-220. [PMID: 36728967 DOI: 10.1097/mbc.0000000000001188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Our team is presenting a patient who is a 57-year -old woman with a past medical history of cerebral vascular accident. The patient presented to the emergency department with symptoms of fever, right upper quadrant pain, and emesis. Initial diagnostic studies revealed thrombocytopenia with acute kidney injury, fever, and leukocytosis. After initiation of treatment for sepsis, the patient developed a hemolytic anemia, which resolved with administration of methylprednisolone. Labs subsequently revealed ADAMTS-13 activity of 4% with positive inhibitor, which confirmed the diagnosis of thrombotic thrombocytopenic purpura (TTP) after the patient's discharge. On retrospective analysis, the case represents a unique and rapid clinical recovery from TTP without administration of therapeutic plasma exchange, rituximab, or caplacizumab.
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Starke SJ, Streiff MB, Brown D, Latifi A, Tuhy T. Double-Negative (PF4-Negative/SRA-Negative) Heparin-Induced Thrombocytopenia. Am J Med 2023; 136:e32-e33. [PMID: 36252705 DOI: 10.1016/j.amjmed.2022.09.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 02/01/2023]
Affiliation(s)
- Samuel J Starke
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md.
| | - Michael B Streiff
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Dannielle Brown
- Department of Pharmacy, The Johns Hopkins Hospital, Baltimore, Md
| | - Ardian Latifi
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Tijana Tuhy
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
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High-frequency Contactless Sensor for the Detection of Heparin-Induced Thrombocytopenia Antibodies via Platelet Aggregation. Int J Mol Sci 2022; 23:ijms232214395. [PMID: 36430873 PMCID: PMC9694871 DOI: 10.3390/ijms232214395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/10/2022] [Accepted: 11/11/2022] [Indexed: 11/22/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT), a severe autoimmune disorder, occurs in patients undergoing heparin therapy. The presence of platelet-activating antibodies against platelet factor 4/Heparin in the blood confirms patients suffering from HIT. The most widely used methods for HIT diagnosis are immunoassays but the results only suit to rule out HIT as the assays provide only around 50% specificity. To confirm HIT, samples with positive results in immunoassays are retested in functional assays (>98% specificity) that track platelet-activating antibodies via platelet aggregation. However, the protocols in functional assays are either time-consuming (due to the requirement of the detection of serotonin release) or require highly trained staff for the visualization of platelets. Here, we applied a cheap and easy-to-use contactless sensor, which employs high-frequency microwaves to detect the changes in the resonant frequency caused by platelet aggregation/activation. Analysis of change in conductivity and permittivity allowed us to distinguish between HIT-like (KKO) and non-HIT-like (RTO) antibodies. KKO caused a stronger reduction of conductivity of platelet samples than RTO. Our results imply that the high-frequency contactless sensor can be a promising approach for the development of a better and easier method for the detection of HIT.
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Jevtic SD, Arnold DM, Modi D, Ivetic N, Bissola AL, Nazy I. Vaccine-induced immune thrombotic thrombocytopenia: Updates in pathobiology and diagnosis. Front Cardiovasc Med 2022; 9:1040196. [PMID: 36352844 PMCID: PMC9637757 DOI: 10.3389/fcvm.2022.1040196] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2023] Open
Abstract
Coronavirus disease 2019 (COVID-19) is a viral respiratory infection caused by the severe acute respiratory syndrome virus (SARS-CoV-2). Vaccines that protect against SARS-CoV-2 infection have been widely employed to reduce the incidence of symptomatic and severe disease. However, adenovirus-based SARS-CoV-2 vaccines can cause a rare, thrombotic disorder termed vaccine-induced immune thrombotic thrombocytopenia (VITT). VITT often develops in the first 5 to 30 days following vaccination and is characterized by thrombocytopenia and thrombosis in unusual locations (e.g., cerebral venous sinus thrombosis). The diagnosis is confirmed by testing for anti-PF4 antibodies, as these antibodies are capable of platelet activation without any cofactor. It can be clinically challenging to differentiate VITT from a similar disorder called heparin-induced thrombocytopenia (HIT), since heparin is commonly used in hospitalized patients. VITT and HIT have similar pathobiology and clinical manifestations but important differences in testing including the need for PF4-enhanced functional assays and the poor reliability of rapid immunoassays for the detection of anti-platelet factor 4 (PF4) antibodies. In this review we summarize the epidemiology of VITT; highlight similarities and differences between HIT and VITT; and provide an update on the clinical diagnosis of VITT.
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Affiliation(s)
- Stefan D. Jevtic
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
- Canadian Blood Services, Hamilton, ON, Canada
| | - Dimpy Modi
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
| | - Nikola Ivetic
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
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Immune Thrombocytopenia following COVID-19 Vaccine. Case Rep Hematol 2022; 2022:6013321. [PMID: 35795543 PMCID: PMC9252767 DOI: 10.1155/2022/6013321] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 04/16/2022] [Accepted: 05/16/2022] [Indexed: 11/25/2022] Open
Abstract
Several vaccines have been developed and are being administered against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Common side effects include fever, chills, headache, myalgia, and soreness at the injection site. However, some rare adverse effects have also been reported. We present a case of induced thrombocytopenia presenting with petechiae and mucosal bleeding which developed as an adverse response after first-dose administration of the Moderna COVID-19 vaccine.
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Cheema T, Kieu T, Balek M, Ahmad M, Singh P. Pulmonary Embolism (PE) in Transit in Heparin-Induced Thrombocytopenia (HIT) With Negative Serotonin-Release Assay (SRA). Cureus 2022; 14:e25868. [PMID: 35698467 PMCID: PMC9188760 DOI: 10.7759/cureus.25868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2022] [Indexed: 11/12/2022] Open
Abstract
Pulmonary embolism (PE) is a potentially lethal condition, although frequently diagnosed, and is rarely associated with transit on initial presentation. Heparin-induced thrombocytopenia (HIT) can cause both arterial thrombus formation and venous thromboembolism. The two forms of HIT must be differentiated in order to guide management. We present a complex and unique case of PE in transit secondary to HIT diagnosed in a patient with a negative serotonin assay.
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Byrne EM, Khattab A, Chen F, Bhagavatula R. Rare presentation of enoxaparin-induced skin necrosis in a postoperative patient. BMJ Case Rep 2022; 15:e249685. [PMID: 35418382 PMCID: PMC9013989 DOI: 10.1136/bcr-2022-249685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2022] [Indexed: 01/18/2023] Open
Abstract
Enoxaparin-induced skin necrosis is a rare complication of low-molecular weight heparin (LMWH) therapy. We describe a woman in her 50s who developed deep vein thrombosis (DVT), thrombocytopenia and necrotic skin lesions after initiation of enoxaparin for DVT prophylaxis. Despite high clinical suspicion of heparin-induced thrombocytopenia syndrome and a positive heparin-platelet factor 4 antibody, heparin serotonin assay was negative. This case emphasises the importance for clinical vigilance regarding complications to LMWH therapy.
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Affiliation(s)
- Emma McNell Byrne
- Allegheny General Hospital, Pittsburgh, Pennsylvania, USA
- Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Ahmed Khattab
- Division of Hematology, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA
| | - Feifan Chen
- Pathology Department, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA
| | - Rama Bhagavatula
- Division of Hematology, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA
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Warkentin TE, Greinacher A. Seminars in Hematology Laboratory testing for VITT antibodies. Semin Hematol 2022; 59:80-88. [DOI: 10.1053/j.seminhematol.2022.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 01/07/2023]
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Warkentin TE. Platelet-activating anti-PF4 disorders: an overview. Semin Hematol 2022; 59:59-71. [DOI: 10.1053/j.seminhematol.2022.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/11/2022]
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15
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Roberge G, Scarvelis D. Long-term anti-PF4 persistence in autoimmune heparin-induced thrombocytopenia: A glimpse into the natural history of vaccine-induced immune thrombotic thrombocytopenia. THROMBOSIS UPDATE 2021. [DOI: 10.1016/j.tru.2021.100067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Sulakshana S, Nayak SS, Perumal S, Das BP. Heparin-Induced Thrombocytopenia in COVID-19: A Systematic Review. Anesth Essays Res 2021; 15:341-347. [PMID: 35422550 PMCID: PMC9004278 DOI: 10.4103/aer.aer_151_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/14/2022] [Accepted: 01/14/2022] [Indexed: 12/22/2022] Open
Abstract
Background: It has been more than a year since the whole world is struggling with COVID-19 pandemic and may experience resurgences in the near future. Along with severe pneumonia, this disease is notorious for extensive thromboembolic manifestations. That is why experts advocated aggressive anticoagulation as a part of the therapy since the beginning. However, from May 2020 onwards, cases of heparin-induced thrombocytopenia (HIT) are being reported. HIT in itself is an autoimmune entity leading to life-threatening thrombosis in the setting of thrombocytopenia. Continuation of heparin can have disastrous consequences in case of unrecognized HIT. Hence, timely recognition of HIT is of utmost value to modify the anticoagulation strategy and salvaging lives. We performed a systemic review trying to find all reported cases of HIT in COVID-19. Methods: It involved extensive search of the databases including PubMed, Google Scholar, Scopus, and Embase in an attempt to find all reported literature in the last 1 year (November 1, 2019–December 25, 2020) using keywords in various combinations. Literature search resulted in a total of 27 articles and 12 articles were finally selected based on the study design and their relevance pertaining to the intervention done and the outcome of interest. Results: A total of 35 patients were included (mean age 56.7 ± 12.8 years, male-to-female ratio = 2:1). The most frequent comorbidity was hypertension. Fifty-seven percent of cases were with low-molecular weight heparin and the rest with unfractionated heparin. Confirmatory functional assay was done in 85.7% of cases (67% by serotonin-release assay [SRA] and 33% by heparin-induced platelet aggregation [HIPA]). All cases tested with HIPA were positive, while with SRA, only 30% were positive. The most common alternate anticoagulation used was argatroban infusion. The new arterial thrombotic event was seen in only 5.7% of cases as repeat myocardial infarction, stroke, and splenic infarction, while clinically significant bleeding was seen in 17.1% of cases. Fifty percent of bleeding episodes were seen where conventional doses of argatroban were used, while no mortality was seen with low-dose argatroban infusion. However, only 45.7% of patients were discharged, 31.4% of patients died, while the outcome was pending for 23% of patients. Conclusion: Severe endotheliitis and immune dysregulation giving rise to HIT antibodies and antiphospholipid antibodies have been demonstrated in COVID-19 and modifying our therapy becomes indispensable when it is pathogenic with potentially fatal consequences. In the light of interim results of REMAP-CAP study in severe COVID-19 cases where heparin does not improve the outcome, the present anticoagulation strategy needs re-evaluation. Unrecognized HIT can be catastrophic and close clinical monitoring is required for patients on heparin therapy.
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Affiliation(s)
- Sulakshana Sulakshana
- Department of Anaesthesiology and Critical Care, Heritage Institute of Medical Sciences, Varanasi, Uttar Pradesh, India
| | | | - Siva Perumal
- Department of Anaesthesiology and Critical Care, SVMCH and RC, Puducherry, India
| | - Badri Prasad Das
- Department of Anaesthesiology and Critical Care, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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17
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Ali Waggiallah H. Thrombosis Formation after COVID-19 Vaccination Immunological Aspects: Review Article. Saudi J Biol Sci 2021; 29:1073-1078. [PMID: 34629931 PMCID: PMC8489518 DOI: 10.1016/j.sjbs.2021.09.065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/04/2021] [Accepted: 09/26/2021] [Indexed: 02/06/2023] Open
Abstract
COVID-19 deteriorates type II pneumocytes and damages the alveolar immunologic balancing process through the inadvertent activation of a sequence of localized and general inflammatory responses. Due to an aggregation of uncleaved angiotensin II, the stimulated inflammatory cells cause cytokines synthesis and secretion (cytokine storming). The cytokines cause the systemic inflammatory response syndrome (SIRS), leading to widespread tissue injuries. Consequently, pro-coagulant factors are activated which increases the microthrombi in different tissues, resulting in ischemia, multiple organ dysfunction syndrome, acute respiratory distress syndrome, and increased mortality. Vaccines recipients (via virus vector technology) have reported the incidence of thrombocytopenia and peculiar thrombotic events. After vaccination, using sera from patients who experienced thrombocytopenia and thrombosis showed increased reactivity in anti-PF4/heparin enzyme immunoassays and substantial platelet-activating antibodies (positive). In some sera of individuals suffering from heparin-induced thrombocytopenia (HIT), it has been observed that platelet-activating antibodies resulting from vaccination tend to bind to non-complexed PF4 alone.
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Affiliation(s)
- Hisham Ali Waggiallah
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Prince Sattam Bin Abdulaziz University
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18
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Datta P, Zhang F, Dordick JS, Linhardt RJ. Platelet factor 4 polyanion immune complexes: heparin induced thrombocytopenia and vaccine-induced immune thrombotic thrombocytopenia. Thromb J 2021; 19:66. [PMID: 34526009 PMCID: PMC8443112 DOI: 10.1186/s12959-021-00318-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/01/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND This is a review article on heparin-induced thrombocytopenia, an adverse effect of heparin therapy, and vaccine-induced immune thrombotic thrombocytopenia, occurring in some patients administered certain coronavirus vaccines. MAIN BODY/TEXT Immune-mediated thrombocytopenia occurs when specific antibodies bind to platelet factor 4 /heparin complexes. Platelet factor 4 is a naturally occurring chemokine, and under certain conditions, may complex with negatively charged molecules and polyanions, including heparin. The antibody-platelet factor 4/heparin complex may lead to platelet activation, accompanied by other cascading reactions, resulting in cerebral sinus thrombosis, deep vein thrombosis, lower limb arterial thrombosis, myocardial infarction, pulmonary embolism, skin necrosis, and thrombotic stroke. If untreated, heparin-induced thrombocytopenia can be life threatening. In parallel, rare incidents of spontaneous vaccine-induced immune thrombotic thrombocytopenia can also occur in some patients administered certain coronavirus vaccines. The role of platelet factor 4 in vaccine-induced thrombosis with thrombocytopenia syndrome further reinforces the importance the platelet factor 4/polyanion immune complexes and the complications that this might pose to susceptible individuals. These findings demonstrate, how auxiliary factors can complicate heparin therapy and drug development. An increasing interest in biomanufacturing heparins from non-animal sources has driven a growing interest in understanding the biology of immune-mediated heparin-induced thrombocytopenia, and therefore, the development of safe and effective biosynthetic heparins. SHORT CONCLUSION In conclusion, these findings further reinforce the importance of the binding of platelet factor 4 with known and unknown polyanions, and the complications that these might pose to susceptible patients. In parallel, these findings also demonstrate how auxiliary factors can complicate the heparin drug development.
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Affiliation(s)
- Payel Datta
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Fuming Zhang
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Jonathan S Dordick
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Robert J Linhardt
- Heparin Applied Research Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
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19
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Abstract
Not applicable (no abstract in Invited Editorial Focus).
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20
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Pishko AM, Cuker A. Diagnosing heparin-induced thrombocytopenia: The need for accuracy and speed. Int J Lab Hematol 2021; 43 Suppl 1:96-102. [PMID: 34288442 DOI: 10.1111/ijlh.13564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/06/2021] [Accepted: 04/14/2021] [Indexed: 01/15/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition resulting from pathogenic antibodies to complexes of heparin and platelet factor 4 (PF4). The diagnosis of HIT can be challenging due to the widespread use of heparin and the frequency of thrombocytopenia in hospitalized patients. Laboratory testing for HIT typically includes an immunoassay to detect antibodies to PF4-heparin and a functional assay. Current HIT diagnostic algorithms recommend using the 4Ts score to determine the need for HIT laboratory testing. Automated calculation of HIT clinical prediction scores in the electronic health record may improve the identification of patients who should undergo HIT testing. Another challenge in the management of patients with suspected HIT is the turnaround time of the laboratory testing needed to confirm the diagnosis. Due to the high daily thrombotic risk of HIT, clinicians must treat patients with intermediate to high pretest likelihood of HIT empirically while awaiting the test results. Treatment for HIT often involves alternative anticoagulants that lack reversal agents, which may increase bleeding risk, prolong hospital stays, and increase costs for patients suspected of having HIT. Rapid immunoassays hold promise to improve the speed of HIT diagnosis. These assays must retain a very high sensitivity for this "can't miss" diagnosis, yet have sufficient specificity to be of diagnostic value. A Bayesian approach has been proposed using two rapid immunoassays in succession, which decreased analytic turnaround time to 60 minutes. Such an approach has the potential to be a much-needed clinical advance in improving accuracy and speed in the diagnosis of HIT.
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Affiliation(s)
- Allyson M Pishko
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Adam Cuker
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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21
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Chan M, Zhao X, Zheng XL. Low ADAMTS-13 predicts adverse outcomes in hospitalized patients with suspected heparin-induced thrombocytopenia. Res Pract Thromb Haemost 2021; 5:e12581. [PMID: 34553121 PMCID: PMC8444283 DOI: 10.1002/rth2.12581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/13/2021] [Accepted: 07/24/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is a life-threatening thrombotic complication after heparin exposure. However, the role of ADAMTS-13 and von Willebrand factor (VWF) in the disease process and outcomes of HIT is not known. OBJECTIVE To determine the potential role of ADAMTS-13 and VWF in hospitalized patients suspected with HIT. METHODS Associations of the HIT tests, ADAMTS-13 activity, and VWF antigen or activity with other clinical parameters and outcomes in the patients suspected with HIT were determined. RESULTS Of 261 patients, 87 (33.3%) were positive and 174 (66.7%) were negative for a HIT antibody determined by an enzyme immunoassay (EIA). Of these 87 EIA+ patients, 31 (35.6%) were also positive but 56 (64.4%) were negative for serotonin-releasing assay (SRA). There was no statistically significant difference among all three groups (i.e., EIA-, EIA+/SRA+, and EIA+/SRA-) as to their demographic features, reasons for admission to the hospital, type of procedures performed, and in-hospital mortality. Compared to those in the healthy controls, plasma ADAMTS-13 activity in patients suspected with HIT was significantly lower but plasma VWF antigen (VWFAg) and activity (VWFAc) in these patients were significantly higher. While there was no statistically significant difference among all three groups regarding plasma levels of ADAMTS-13 activity, VWFAg, and VWFAc, plasma levels of ADAMTS-13 activity <50% or the low ratios of ADAMTS-13 activity to VWFAg (or VWFAc) are highly predictive for a 90-day mortality rate, particularly in the EIA+SRA+ group. CONCLUSIONS These results demonstrate that relative deficiency of plasma ADAMTS-13 activity in hospitalized patients suspected with HIT is common, which may contribute at least in part to the adverse outcomes in this patient population, particularly in those with true HIT.
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Affiliation(s)
- Meng Chan
- Departments of Pathology and Laboratory MedicineThe University of Kansas Medical CenterKansas CityKSUSA
| | - Xinyang Zhao
- Departments of Biochemistry and Molecular GeneticsThe University of Alabama at BirminghamBirminghamALUSA
| | - X. Long Zheng
- Departments of Pathology and Laboratory MedicineThe University of Kansas Medical CenterKansas CityKSUSA
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22
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Can Heparin-Coated ECMO Cannulas Induce Thrombocytopenia in COVID-19 Patients? Case Reports Immunol 2021; 2021:6624682. [PMID: 34194852 PMCID: PMC8184338 DOI: 10.1155/2021/6624682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 04/27/2021] [Accepted: 05/21/2021] [Indexed: 12/14/2022] Open
Abstract
Extracorporeal membrane oxygenation (ECMO) is often used in the management of COVID-19-related severe respiratory failure. We report the first case of a patient with COVID-19-related ARDS on ECMO support who developed symptoms of heparin-induced thrombocytopenia (HIT) in the absence of heparin therapy. A low platelet count of 61 G/L was accompanied by the presence of circulating HIT antibodies 12 days after ECMO initiation. Replacement of the ECMO system including cannulas resulted in the normalization of the platelet count. However, the clinical situation did not improve, and the patient died 9 days later. Careful consideration of anticoagulant therapy and ECMO circuit, as well as routine HIT antibody testing, may prevent a fatal course in ECMO-supported COVID-19 patients.
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23
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Rubino JG, Arnold DM, Warkentin TE, Smith JW, Kelton JG, Nazy I. A comparative study of platelet factor 4-enhanced platelet activation assays for the diagnosis of heparin-induced thrombocytopenia. J Thromb Haemost 2021; 19:1096-1102. [PMID: 33387395 DOI: 10.1111/jth.15233] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/06/2020] [Accepted: 12/28/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND Functional platelet activation assays, such as the serotonin release assay (SRA), are the gold standard for the diagnosis of heparin-induced thrombocytopenia (HIT). Recently, platelet activation assays using added platelet factor 4 (PF4) have been described and suggest improved sensitivity. Direct comparisons of these assays have not been performed. OBJECTIVE We compare the performance characteristics of three PF4-enhanced platelet activation assays, the PF4/heparin-SRA (PF4/hep-SRA), the PF4-SRA, and the P-selectin expression assay (PEA), at a single reference laboratory. METHODS Serum samples from two cohorts of patients were used. The referral cohort (n = 84) included samples that had previously undergone routine diagnostic testing for HIT and tested positive or negative using the SRA. The clinical cohort (n = 101) consisted of samples from patients with clinically confirmed HIT whose serum contained platelet-activating antibodies. We simultaneously tested all samples in PF4-enhanced SRA-based assays (PF4/hep-SRA, PF4-SRA) and the flow cytometry-based PEA. RESULTS In the referral cohort, the three PF4-enhanced assays identified all samples that were previously determined to be positive in the SRA. However, specificity of the PF4/hep-SRA was 96.6%, the PF4-SRA was 84.7%, and the PEA was 67.8%. In the clinical cohort of samples, all SRA-based assays displayed high performance characteristics (>92.1% sensitivity, >98.4% specificity). Sensitivity and specificity of the PEA was the lowest, 65.8% and 63.5%, respectively; but improved to 92.1% and 96.8% using preselected platelet donors. CONCLUSIONS All PF4-enhanced assays demonstrated good performance characteristics when platelet donors were preselected. Further comparisons across multiple laboratories should be conducted for consensus on optimal HIT diagnostic testing.
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Affiliation(s)
- Julian G Rubino
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Theodore E Warkentin
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - James W Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - John G Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
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24
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Warkentin TE, Smythe MA, Ali MA, Aslam N, Sheppard JI, Smith JW, Moore JC, Arnold DM, Nazy I. Serotonin-release assay-positive but platelet factor 4-dependent enzyme-immunoassay negative: HIT or not HIT? Am J Hematol 2021; 96:320-329. [PMID: 33326124 DOI: 10.1002/ajh.26075] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/28/2022]
Abstract
IgG-specific and polyspecific PF4-dependent enzyme-immunoassays (EIAs) have exceptionally high sensitivity (≥99%) for diagnosis of heparin-induced thrombocytopenia (HIT), a drug reaction caused by platelet-activating antibodies detectable by serotonin-release assay (SRA). The IgG-specific EIAs are recommended for screening, as their high sensitivity is accompanied by relatively high specificity vis-à-vis polyspecific EIAs. We investigated the frequency of SRA-positive/EIA-negative (SRA+/EIA-) HIT, prompted by referral to our reference HIT laboratory of serial blood samples from a patient ("index case") with false-negative IgG-specific EIAs. Despite initial clinical suspicion for HIT, repeat negative IgG-specific EIAs prompted heparin resumption, which triggered recurrent thrombocytopenia and near-fatal cardiac arrest, indicating likely post-heparin HIT-associated anaphylactoid reaction. Further investigations revealed a strong-positive SRA, whether performed with heparin alone, PF4 alone, or PF4/heparin, with inhibition by Fc receptor-blocking monoclonal antibody (indicating IgG-mediated platelet activation); however, five different IgG-specific immunoassays yielded primarily negative (or weak-positive) results. To investigate the frequency of SRA+/EIA- HIT, we reviewed the laboratory and clinical features of patients with this serological profile during a 6-year period in which our reference laboratory investigated for HIT using both SRA and IgG-specific EIA. Although ~0.2% of 8546 patients had an SRA+/EIA- profile, further review of 15 such cases indicated clerical/laboratory misclassification or false-positive SRA in all, with no SRA+/EIA- HIT case identified. We conclude that while SRA+/EIA- HIT is possible-as shown by our index case-this clinical picture is exceptionally uncommon. Moreover, the requirement for a positive EIA is a useful quality control maneuver that reduces risk of reporting a false-positive SRA result.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Maureen A. Smythe
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
- Department of Pharmacy Practice Wayne State University Detroit Michigan USA
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Mona A. Ali
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
| | - Naveed Aslam
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - James W. Smith
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Jane C. Moore
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Donald M. Arnold
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Ishac Nazy
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
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25
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Samuelson Bannow B, Warad DM, Jones CG, Pechauer SM, Curtis BR, Bougie DW, Sharma R, Grill DE, Redman MW, Khalighi PR, Leger RR, Pruthi RK, Chen D, Sabath DE, Aster RH, Garcia DA, Padmanabhan A. A prospective, blinded study of a PF4-dependent assay for HIT diagnosis. Blood 2021; 137:1082-1089. [PMID: 32898858 PMCID: PMC7907721 DOI: 10.1182/blood.2020008195] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/23/2020] [Indexed: 12/22/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14-labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.
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Affiliation(s)
| | - Deepti M Warad
- Department of Pediatric and Adolescent Medicine and
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | | | - Brian R Curtis
- Platelet and Neutrophil Immunology Laboratory, Versiti Wisconsin, Milwaukee, WI
| | | | - Ruchika Sharma
- Platelet and Neutrophil Immunology Laboratory, Versiti Wisconsin, Milwaukee, WI
| | - Diane E Grill
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | | | - Parisa R Khalighi
- Department of Obstetrics and Gynecology, University of Colorado, Denver, CO
| | - Rachel R Leger
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Rajiv K Pruthi
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
- Department of Medicine, Mayo Clinic, Rochester, MN; and
| | - Dong Chen
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Daniel E Sabath
- Department of Laboratory Medicine and
- Department of Medicine, University of Washington, Seattle, WA
| | | | - David A Garcia
- Department of Medicine, University of Washington, Seattle, WA
| | - Anand Padmanabhan
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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26
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Heparin-Induced Thrombocytopenia: A Review of New Concepts in Pathogenesis, Diagnosis, and Management. J Clin Med 2021; 10:jcm10040683. [PMID: 33578859 PMCID: PMC7916628 DOI: 10.3390/jcm10040683] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 12/17/2022] Open
Abstract
Knowledge on heparin-induced thrombocytopenia keeps increasing. Recent progress on diagnosis and management as well as several discoveries concerning its pathogenesis have been made. However, many aspects of heparin-induced thrombocytopenia remain partly unknown, and exact application of these new insights still need to be addressed. This article reviews the main new concepts in pathogenesis, diagnosis, and management of heparin-induced thrombocytopenia.
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27
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Koster A, Erdoes G, Nagler M, Birschmann I, Alberio L. How would we treat our own heparin-induced thrombocytopenia during cardiac surgery? J Cardiothorac Vasc Anesth 2020; 35:1585-1593. [PMID: 33342734 DOI: 10.1053/j.jvca.2020.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 12/29/2022]
Abstract
The aim of this article is to provide a comprehensive review of the current state of knowledge on heparin-induced thrombocytopenia (HIT) in cardiac surgery. The management of HIT patients undergoing cardiac surgery with cardiopulmonary bypass is complex and requires an interdisciplinary and patient-tailored approach because available evidence is limited and current anticoagulation strategies have potential risks. An index case is used to discuss both the established and new perioperative therapeutic options in HIT patients undergoing urgent cardiac surgery with cardiopulmonary bypass.
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Affiliation(s)
- Andreas Koster
- Institute of Anesthesiology and Pain Therapy, Heart, and Diabetes Center NRW, Bad Oeynhausen, Ruhr-University Bochum, Bochum, Germany
| | - Gabor Erdoes
- Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
| | - Michael Nagler
- University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Ingvild Birschmann
- Institute of Laboratory and Transfusion Medicine, Heart, and Diabetes Center NRW, Bad Oeynhausen, Ruhr-University Bochum, Bochum, Germany
| | - Lorenzo Alberio
- Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV), University of Lausanne (UNIL), Lausanne, Switzerland
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28
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Warkentin TE. Challenges in Detecting Clinically Relevant Heparin-Induced Thrombocytopenia Antibodies. Hamostaseologie 2020; 40:472-484. [PMID: 33091948 PMCID: PMC7581458 DOI: 10.1055/a-1223-3329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an antibody-mediated hypercoagulable state featuring high thrombosis risk and distinct pathogenesis involving immunoglobulin G-mediated platelet activation. The target of the immune response is a cationic “self” protein, platelet factor 4 (PF4), rendered antigenic by heparin. A key problem is that only a minority of anti-PF4/polyanion antibodies induced by heparin are pathogenic, i.e., capable of causing platelet activation and thereby clinical HIT. Since thrombocytopenia occurs frequently in hospitalized, heparin-treated patients, testing for “HIT antibodies” is common; thus, the problem of distinguishing between pathogenic and nonpathogenic antibodies is important. The central concept is that those antibodies that have platelet-activating properties demonstrable in vitro correlate well with pathogenicity, as shown by platelet activation tests such as the serotonin-release assay (SRA) and heparin-induced platelet activation assay. However, in most circumstances, immunoassays are used for first-line testing, and so it is important for clinicians to appreciate which immunoassay result profiles—in the appropriate clinical context—predict the presence of platelet-activating antibodies (Bayesian analysis). Clinicians with access to rapid, on-demand HIT immunoassays (e.g., particle gel immunoassay, latex immunoturbidimetric assay, chemiluminescent immunoassay) can look beyond simple dichotomous result interpretation (“negative”/“positive”) and incorporate semiquantitative interpretation, where, for example, a strong-positive immunoassay result (or even combination of two immunoassays) points to a greater probability of detecting platelet-activating antibodies, and hence supporting a diagnosis of HIT. Recent recognition of “SRA-negative HIT” has increased the importance of semiquantitative interpretation of immunoassays, given that strong immunoassay reactivity is a potential clue indicating possible HIT despite a (false) negative platelet activation assay.
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada.,Service of Clinical Hematology, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada.,McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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29
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Warkentin TE, Cook RJ, Greinacher A. Limitations of the particle immunofiltration assay test for diagnosis of heparin-induced thrombocytopenia. Am J Hematol 2020; 95:E250-E254. [PMID: 32510647 PMCID: PMC7496181 DOI: 10.1002/ajh.25901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/31/2020] [Accepted: 06/02/2020] [Indexed: 12/30/2022]
Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of Medicine, McMaster UniversityHamiltonOntarioCanada
- Department of MedicineMichael G. DeGroote School of Medicine, McMaster UniversityHamiltonOntarioCanada
| | - Richard J. Cook
- Department of Statistics and Actuarial ScienceUniversity of WaterlooWaterlooOntarioCanada
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin GreifswaldGreifswaldGermany
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30
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Abstract
A striking feature of COVID-19 is the high frequency of thrombosis, particularly in patients who require admission to intensive care unit because of respiratory complications (pneumonia/adult respiratory distress syndrome). The spectrum of thrombotic events is wide, including in situ pulmonary thrombosis, deep-vein thrombosis and associated pulmonary embolism, as well as arterial thrombotic events (stroke, myocardial infarction, limb artery thrombosis). Unusual thrombotic events have also been reported, e.g., cerebral venous sinus thrombosis, mesenteric artery and vein thrombosis. Several hematology abnormalities have been observed in COVID-19 patients, including lymphopenia, neutrophilia, thrombocytopenia (usually mild), thrombocytosis, elevated prothrombin time and partial thromboplastin times (the latter abnormality often indicating lupus anticoagulant phenomenon), hyperfibrinogenemia, elevated von Willebrand factor levels, and elevated fibrin d-dimer. Many of these abnormal hematologic parameters—even as early as the time of initial hospital admission—indicate adverse prognosis, including greater frequency of progression to severe respiratory illness and death. Progression to overt disseminated intravascular coagulation in fatal COVID-19 has been reported in some studies, but not observed in others. We compare and contrast COVID-19 hypercoagulability, and associated increased risk of venous and arterial thrombosis, from the perspective of heparin-induced thrombocytopenia (HIT), including the dilemma of providing thromboprophylaxis and treatment recommendations when available data are limited to observational studies. The frequent use of heparin—both low-molecular-weight and unfractionated—in preventing and treating COVID-19 thrombosis, means that vigilance for HIT occurrence is required in this patient population. HIT and COVID-19 are associated with a high risk of thrombosis (venous > arterial). HIT and COVID-19 both feature coagulation and “pancellular” activation. Therapeutic anticoagulation is indicated for HIT, but dosing unknown for COVID-19.
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Riker RR, May TL, Fraser GL, Gagnon DJ, Bandara M, Zemrak W, Seder DB. Response to The challenges of diagnosing heparin-induced thrombocytopenia in patients with COVID-19. Res Pract Thromb Haemost 2020; 4:1068-1069. [PMID: 32838110 PMCID: PMC7361545 DOI: 10.1002/rth2.12417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 07/01/2020] [Indexed: 11/30/2022] Open
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Koster A, Nazy I, Birschmann IE, Smith JW, Sheppard JI, Warkentin TE. High-dose IVIG plus cangrelor platelet "anesthesia" during urgent heparin-CPB in a patient with recent SRA-negative HIT-thrombosis with persisting platelet-activating antibodies. Res Pract Thromb Haemost 2020; 4:1060-1064. [PMID: 32864557 PMCID: PMC7443421 DOI: 10.1002/rth2.12348] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/31/2020] [Indexed: 11/24/2022] Open
Abstract
In a high-risk patient with subacute heparin-induced thrombocytopenia (HIT) type A (platelet count recovery following acute HIT but with persisting platelet-activating antibodies), in whom urgent cardiac surgery was required, a key clinical question arose: could intraoperative heparin be given safely with "platelet anesthesia" provided with high-dose intravenous immunoglobulin (IVIG) plus cangrelor (ultra-short-acting antiplatelet agent)? This approach proved successful, without unexpected postoperative thrombocytopenia or thromboembolism. In vitro studies confirmed that both IVIG and cangrelor contributed to perioperative inhibition of HIT antibody-induced platelet activation. Interestingly, despite the patient testing strongly positive in 4 HIT immunoassays (latex immunoturbidimetric assay and 3 enzyme-immunoassays), the serotonin-release assay (SRA) was consistently negative. Nevertheless, platelet-activating HIT antibodies were detectable using modified (platelet factor 4-enhanced) SRA. Our protocol of heparin rechallenge following IVIG/cangrelor provides both intraoperative and early postoperative inhibition of HIT antibody-induced platelet activation and is applicable to patients with circulating functional HIT antibodies requiring urgent heart surgery, including those with "SRA-negative HIT."
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Affiliation(s)
- Andreas Koster
- Institute of Anesthesiology and Pain Therapy, Heart and Diabetes Center NRWRuhr‐University BochumBad OeynhausenGermany
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Ingvild E. Birschmann
- Institute of Laboratory and Transfusion Medicine, Heart and Diabetes Center NRWRuhr‐University BochumBad OeynhausenGermany
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Theodore E. Warkentin
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
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Riker RR, May TL, Fraser GL, Gagnon DJ, Bandara M, Zemrak WR, Seder DB. Heparin-induced thrombocytopenia with thrombosis in COVID-19 adult respiratory distress syndrome. Res Pract Thromb Haemost 2020; 4:936-941. [PMID: 32685905 PMCID: PMC7276726 DOI: 10.1002/rth2.12390] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/08/2020] [Accepted: 05/13/2020] [Indexed: 01/08/2023] Open
Abstract
Early reports of coronavirus disease 2019 (COVID-19) clinical features describe a hypercoagulable state, and recent guidelines recommend prophylactic anticoagulation for patients with COVID-19 with low-molecular-weight heparin, but this would be contraindicated in the presence of heparin-induced thrombocytopenia (HIT). We address the key clinical question whether HIT is also present during COVID-19. We report 3 cases of thrombocytopenia with antiplatelet factor 4 antibodies among 16 intubated patients with COVID-19 with adult respiratory distress syndrome, a higher-than-expected incidence of 19%. Each patient had evidence of thrombosis (pulmonary embolism, upper extremity venous thromboses, and skin necrosis, respectively). The serotonin release assay confirmed HIT in 1 case, and 2 cases were negative. We believe this is the first reported case of HIT during the COVID-19 pandemic. Recognition that the thrombocytopenia represented HIT in the confirmed case was delayed. We recommend clinicians monitor platelet counts closely during heparin therapy, with a low threshold to evaluate for HIT.
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Warkentin TE, Sheppard JI, Smith JW, Li N, Moore JC, Arnold DM, Nazy I. Combination of two complementary automated rapid assays for diagnosis of heparin-induced thrombocytopenia (HIT). J Thromb Haemost 2020; 18:1435-1446. [PMID: 32167669 PMCID: PMC7317897 DOI: 10.1111/jth.14794] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/10/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND HIT diagnosis typically uses complementary diagnostic assays (eg, a PF4-dependent enzyme-immunoassay [EIA] and a platelet activation assay such as the serotonin-release assay [SRA]). OBJECTIVES To determine whether the combination of two automated assays-a latex immunoturbidimetric assay (LIA) that evaluates competitive inhibition of a HIT-like monoclonal antibody and a chemiluminescence immunoassay (CLIA) for detecting anti-PF4/heparin IgG-optimizes diagnostic sensitivity while also yielding good specificity, particularly at high assay reactivities. PATIENTS/METHODS We determined operating characteristics using combined LIA/CLIA results from a HIT observational trial (n = 430; derivation cohort) and 147 consecutive patients with HIT (n = 147; supplementary derivation cohort). We also evaluated 678 consecutive samples referred for HIT testing (replication cohort). LIA/CLIA reactivities were scored individually as "negative" (<1.00 U/mL, 0 points), "weak" (1.00-4.99 U/mL, 1 point), "moderate" (5.00-15.99 U/mL, 2 points) and "strong" (≥16.00 U/mL, 3 points), thus contributing up to 6 points (maximum) when LIA/CLIA results were combined. We also examined whether higher LIA/CLIA scores predicted presence of platelet-activating antibodies by conventional and modified (PF4- or PF4/heparin-enhanced) SRA. RESULTS Combined LIA/CLIA testing yielded high diagnostic sensitivity (~99%) similar to EIA. Interpretation of LIA/CLIA results using the 6-point scale indicated progressively greater likelihood for the presence of platelet-activating antibodies with increasing scores (semi-quantitative reactivity). A LIA/CLIA score ≥ 4 points predicted the presence of platelet-activating antibodies by SRA or PF4-enhanced SRA with high probability (~98%). CONCLUSION Combined LIA/CLIA testing optimizes diagnostic sensitivity, with progressively greater probability of detecting platelet-activating antibodies with higher assay reactivity that reaches 98% when both automated assays yield moderate or strong results.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- Hamilton Regional Laboratory Medicine ProgramHamilton Health SciencesHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Na Li
- McMaster Centre for Transfusion ResearchHamiltonONCanada
- Department of Computing and SoftwareMcMaster UniversityHamiltonONCanada
| | - Jane C. Moore
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Donald M. Arnold
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
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Tardy B, Lecompte T, Mullier F, Vayne C, Pouplard C. Detection of Platelet-Activating Antibodies Associated with Heparin-Induced Thrombocytopenia. J Clin Med 2020; 9:jcm9041226. [PMID: 32344682 PMCID: PMC7230370 DOI: 10.3390/jcm9041226] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/19/2020] [Indexed: 12/13/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic immune drug reaction caused by platelet-activating antibodies that in most instances recognize platelet factor 4 (PF4)/polyanion complexes. Platelet activation assays (i.e., functional assays) are more specific than immunoassays, since they are able to discern clinically relevant heparin-induced antibodies. All functional assays used for HIT diagnosis share the same principle, as they assess the ability of serum/plasma from suspected HIT patients to activate fresh platelets from healthy donors in the presence of several concentrations of heparin. Depending on the assay, donors’ platelets are stimulated either in whole blood (WB), platelet-rich plasma (PRP), or in a buffer medium (washed platelets, WP). In addition, the activation endpoint studied varies from one assay to another: platelet aggregation, membrane expression of markers of platelet activation, release of platelet granules. Tests with WP are more sensitive and serotonin release assay (SRA) is considered to be the current gold standard, but functional assays suffer from certain limitations regarding their sensitivity, specificity, complexity, and/or accessibility. However, the strict adherence to adequate preanalytical conditions, the use of selected platelet donors and the inclusion of positive and negative controls in each run are key points that ensure their performances.
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Affiliation(s)
- Brigitte Tardy
- Inserm U1059 Sainbiose, University of Lyon St Etienne, CIC 1408, FCRIN-INNOVTE, Hémostase Clinique CHU, 42055 Saint Etienne, France
| | - Thomas Lecompte
- Department of Medicine, Geneva University Hospitals, and Geneva Platelet Group (GpG), Faculty of Medicine, University of Geneva, CH-1211 Genève 14
| | - François Mullier
- CHU UCL Namur, Namur Thrombosis and Hemostasis center (NTHC), Hematology Laboratory, Université Catholique de Louvain, 5530 Yvoir, Belgium
| | - Caroline Vayne
- Department of Hemostasis, University Hospital of Tours, 37044 Tours, France
- University of Tours, EA 7501 GICC, 37000 Tours, France
| | - Claire Pouplard
- Department of Hemostasis, University Hospital of Tours, 37044 Tours, France
- University of Tours, EA 7501 GICC, 37000 Tours, France
- Correspondence:
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