Treatment and outcomes of heparin-induced thrombocytopenia (HIT) in patients with neoplasm, a case series.

Heparin-induced thrombocytopenia (HIT) is a highly thrombogenic condition. Cancer patients are already at high risk of thrombosis. The treatment and outcomes of HIT in cancer patients are not well established. We retrospectively identified patients with active cancer who were diagnosed with HIT at our institution. Only patients with a positive HIT assay and intermediate to high 4Ts score were included. We assessed patients for baseline characteristics, HIT characteristics, non-heparin agent usage, and outcomes (recurrent thrombosis, bleeding, and death) up to 180 days after diagnosis of HIT. Between November 1, 2006 and December 31, 2016, 39 patients with active cancer received a diagnosis of HIT. Of these, 35.9% had thrombotic complications at diagnosis. Gastrointestinal cancer was the most common solid organ malignancy while myeloproliferative neoplasm (MPN) was the most common hematological malignancy. Fondaparinux was the most often used parenteral agent at any point of follow-up (87.2%), followed by argatroban (41.0%). Less than half the patients transitioned to an oral agent. The recurrent thrombosis rate was 17.9%, the bleeding rate was 20.5%, the major bleeding rate was 10.3%, and the mortality rate was 15.4% in the entire cohort. HIT in cancer patients is associated with poor outcomes.

Evaluation of intravenous direct thrombin inhibitor monitoring tests: Correlation with plasma concentrations and clinical outcomes in hospitalized patients.

The parenterally administered direct thrombin inhibitors (DTIs) argatroban and bivalirudin are effective anticoagulants for acute heparin-induced thrombocytopenia (HIT) treatment. The activated partial thromboplastin time (aPTT) has classically been used as the monitoring test to assess degree of anticoagulation, however concerns exist with using aPTT to monitor DTI therapy. In this observational study plasma samples from DTI treated patients were analyzed by aPTT, dilute thrombin time (dTT) and ecarin chromogenic assay (ECA) to delineate results into concordant and discordant groups. Discordant samples were further analyzed via liquid chromatography with tandem mass spectrometry (LC MS/MS). In total 101 patients with 198 samples were evaluated. Discordance between tests were frequent (59% of DTI treated patients). Bivalirudin aPTT vs dTT discordance was observed in 45% (57/126) of samples. Amongst bivalirudin samples with test discordance dTT results were more likely to be concordant with LC MS/MS than the aPTT (77% vs 9%, p < 0.0001). Argatroban aPTT vs dTT discordance was observed in 43% (31/72) and aPTT vs ECA discordance was observed in 40% (29/72) of samples. Amongst argatroban samples with test discordance both the dTT and ECA tests were more likely to have concordant results with LC MS/MS than the aPTT (88% vs 9%, p < 0.0001 for both dTT and ECA tests). There were no differences between discordant and concordant patient groups in a composite outcome of bleeding/thrombosis rate (23% vs 27%, p = 0.689). Further investigation is warranted to elucidate the effect of suitable monitoring assays on patient outcomes in the setting of DTI therapy.

Comparison of different anticoagulation strategies for renal replacement therapy in critically ill patients with COVID-19: a cohort study.

BACKGROUND: Critically ill coronavirus disease 2019 (COVID-19) patients have a high risk of acute kidney injury (AKI) that requires renal replacement therapy (RRT). A state of hypercoagulability reduces circuit life spans. To maintain circuit patency and therapeutic efficiency, an optimized anticoagulation strategy is needed. This study investigates whether alternative anticoagulation strategies for RRT during COVID-19 are superior to administration of unfractionated heparin (UFH). METHODS: Retrospective cohort study on 71 critically ill COVID-19 patients (≥18 years), admitted to intensive care units at a tertiary health care facility in the southwestern part of Germany between February 26 and May 21, 2020. We collected data on the disease course, AKI, RRT, and thromboembolic events. Four different anticoagulatory regimens were administered. Anticoagulation during continuous veno-venous hemodialysis (CVVHD) was performed with UFH or citrate. Anticoagulation during sustained low-efficiency daily dialysis (SLEDD) was performed with UFH, argatroban, or low molecular weight heparin (LMWH). Primary outcome is the effect of the anticoagulation regimen on mean treatment times of RRT. RESULTS: In patients receiving CVVHD, mean treatment time in the UFH group was 21.3 h (SEM: ±5.6 h), in the citrate group 45.6 h (SEM: ±2.7 h). Citrate anticoagulation significantly prolonged treatment times by 24.4 h (P = .001). In patients receiving SLEDD, mean treatment time with UFH was 8.1 h (SEM: ±1.3 h), with argatroban 8.0 h (SEM: ±0.9 h), and with LMWH 11.8 h (SEM: ±0.5 h). LMWH significantly prolonged treatment times by 3.7 h (P = .008) and 3.8 h (P = .002), respectively. CONCLUSIONS: UFH fails to prevent early clotting events in the dialysis circuit during COVID-19. For patients, who do not require effective systemic anticoagulation, regional citrate dialysis is the most effective strategy. For patients, who require effective systemic anticoagulation, the usage of LMWH results in the longest circuit life spans. The proposed anticoagulatory strategies are safe, can easily be monitored, and allow an individualized treatment.

Survey of Anticoagulation Practices with the Impella Percutaneous Ventricular Assist Device at High-Volume Centers.

OBJECTIVES: To characterize anticoagulation practices with the Impella percutaneous ventricular assist device (pVAD). BACKGROUND: Managing anticoagulation in patients being supported by the Impella pVAD is made challenging by several unique features of the device. These include the release of a dextrose-based purge solution containing unfractionated heparin (UFH), the need to concurrently administer systemic anticoagulation with intravenous UFH, and the lack of an alternative strategy in patients with contraindications to UFH. METHODS: To characterize anticoagulation practices with the Impella pVAD, we conducted a survey of centers in the United States performing a high volume of Impella cases, which we defined as > 1 per month. Centers were contacted via email or phone and individuals who agreed to participate were provided with a link to complete the survey online. The primary measures of interest were variations in practice across centers and variations from the manufacturer's recommendations. RESULTS: Practices varied considerably among respondents (65 of 182 centers, or 35.7%) and often diverged from manufacturer recommendations. Approximately half of centers (52.4%) reported using a UFH concentration of 50 units/mL in the purge solution, whereas most of the remaining centers (41.3%) reported using lower concentrations. Strategies for the initiation and adjustment of systemic therapy also varied, as did practices for routinely monitoring for hemolysis. Nearly one-fifth of centers (16.7%) had not developed an alternative strategy for the purge solution in patients with contraindications to UFH. Most centers (58.4%) reported using argatroban or bivalirudin in this scenario, a strategy that diverges from the manufacturer's recommendations. CONCLUSIONS: Given these findings, studies to determine a systematic approach to anticoagulation with the Impella device are warranted.

Inpatient management strategies in a severe case of heparin-induced thrombocytopenia.

We present important laboratory testing and clinical management strategies used to safely discharge home a 69-year old woman with heparin-induced thrombocytopenia (HIT) from the hospital. She was admitted for a coronary artery bypass graft procedure for which she was anticoagulated with heparin. Shortly after the procedure she developed thrombocytopenia and was diagnosed with HIT using the 4Ts scoring system, a latex-enhanced immunoassay (LEI) screen and confirmatory serotonin release assay. Her anticoagulation was switched from heparin to argatroban, and response to treatment was monitored in the laboratory using LEI. Unfortunately, she also received platelet transfusions and subsequently developed multifocal deep vein thrombosis with worsening platelet counts with nadir less than 10 x 10^3/µL. After five therapeutic plasma exchange procedures we noted an improvement in platelet counts, which plateaued into the 50s x 10^3/µL. Furthermore, the LEI remained positive. At this juncture we decided to transition from argatroban to fondaparinux so that she could leave the hospital in stable condition. Upon follow-up with hematology she exhibited no worsening clinical signs or symptoms of disease, and platelet counts markedly improved to within normal limits of detection. In this report we examine the utility of LEI in monitoring patients with HIT, therapeutic plasma exchange in the management of severe HIT (with thrombosis), and the use of subcutaneous fondaparinux in managing HIT in the outpatient setting.

Evaluation of anticoagulant agents for the treatment of human metapneumovirus infection in mice.

Thrombin has been demonstrated to be involved in several viral diseases including human metapneumovirus (hMPV) infections. We previously showed that immediate administration of thrombin inhibitor argatroban post-infection protected mice against hMPV disease. This current work aims at determining whether warfarin and heparin, two other anticoagulants inhibiting thrombin formation and activities, may also be used for treatment against hMPV in vivo. We found that immediate injections of argatroban, warfarin or heparin after virus challenge protected mice against hMPV infection, as evidenced by decreased or no mortality, less weight loss, reduced viral load and attenuated inflammation. However, delayed treatments starting 1 day post-infection with argatroban or warfarin almost did not impact the survival whereas delayed treatment with heparin induced an increased mortality during infection. Moreover, these treatments also did not reduce weight loss, viral replication and inflammation. In agreement with these results, thrombin generation was decreased upon immediate anticoagulant treatments but was unaltered upon delayed treatments. Thus, thrombin generation occurs at the onset of hMPV infection and thrombin inhibition may be only useful for the treatment of this disease when initiated in the early stage. In this case, heparin is not recommended because of its reduced efficacy on mortality in infected mice whereas argatroban and warfarin appear as safe and effective drugs for the treatment of hMPV disease. The antiviral and anti-inflammatory effects of argatroban occur via thrombin-dependent pathways whereas the mechanisms by which warfarin exerts its beneficial effects against hMPV infection were not elucidated and need to be further studied.

Comparison of argatroban and fondaparinux for the management of patients with isolated heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a serious complication of the administration of heparin and its derivatives. Non-heparin anticoagulants such as argatroban and fondaparinux are widely used in the management of HIT to compare the effectiveness of argatroban and fondaparinux in the resolution of thrombocytopenia and to compare clinical outcomes in patients with isolated HIT. A retrospective cohort analysis was performed at King Abdulaziz Medical City (KAMC) on patients diagnosed with isolated HIT between 31 Jan, 2014 and 30 June, 2017. Demographics data, non-heparin anticoagulants, related laboratory results, and clinical outcomes were retrieved and analysed. The cohort comprised a total of 95 adult patients who received either argatroban (56 patients) or fondaparinux (39 patients) for isolated HIT. The median age and sex distribution were similar in both argatroban and fondaparinux groups. The mean (+ SD) time (in days) for the resolution of thrombocytopenia was 3.5 (± 1.8) for patients who received argatroban and 3.7 (± 1.7) for patients administered fondaparinux (p = 0.843). Thromboembolic events occurred in five patients (8.9%) administered argatroban and in three patients (7.7%) administered fondaparinux (p = 0.382). There was no significant difference in the rates of bleeding or death (p = 0.829); however, the small number of cases limits our ability to draw conclusions about these outcomes. In this retrospective study, fondaparinux and argatroban were similarly effective in resolving thrombocytopenia, preventing further thromboembolic events, and maintaining safety in patients with confirmed HIT. To confirm this observation, larger prospective studies are needed.

Randomized, Multicenter Trial of ARTSS-2 (Argatroban With Recombinant Tissue Plasminogen Activator for Acute Stroke).

BACKGROUND AND PURPOSE: We conducted a randomized exploratory study to assess safety and the probability of a favorable outcome with adjunctive argatroban, a direct thrombin-inhibitor, administered to recombinant tissue-type plasminogen activator (r-tPA)-treated ischemic stroke patients. METHODS: Patients treated with standard-dose r-tPA, not receiving endovascular therapy, were randomized to receive no argatroban or argatroban (100 µg/kg bolus) followed by infusion of either 1 (low dose) or 3 µg/kg per minute (high dose) for 48 hours. Safety was incidence of symptomatic intracerebral hemorrhage. Probability of clinical benefit (modified Rankin Scale score 0-1 at 90 days) was estimated using a conservative Bayesian Poisson model (neutral prior probability centered at relative risk, 1.0 and 95% prior intervals, 0.33-3.0). RESULTS: Ninety patients were randomized: 29 to r-tPA alone, 30 to r-tPA+low-dose argatroban, and 31 to r-tPA+high-dose argatroban. Rates of symptomatic intracerebral hemorrhage were similar among control, low-dose, and high-dose arms: 3/29 (10%), 4/30 (13%), and 2/31 (7%), respectively. At 90 days, 6 (21%) r-tPA alone, 9 (30%) low-dose, and 10 (32%) high-dose patients were with modified Rankin Scale score 0 to 1. The relative risks (95% credible interval) for modified Rankin Scale score 0 to 1 with low, high, and either low or high dose argatroban were 1.17 (0.57-2.37), 1.27 (0.63-2.53), and 1.34 (0.68-2.76), respectively. The probability that adjunctive argatroban was superior to r-tPA alone was 67%, 74%, and 79% for low, high, and low or high dose, respectively. CONCLUSIONS: In patients treated with r-tPA, adjunctive argatroban was not associated with increased risk of symptomatic intracerebral hemorrhage and provides evidence that a definitive effectiveness trial is indicated. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique Identifier: NCT01464788.

Anticoagulation in children: Making the most of little patients and little evidence.

Thrombotic complications are increasing at a steady and significant rate in children resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the standard agents (heparin, low molecular weight heparin, and vitamin K antagonists) and alternative agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the standard and alternative anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. Clearly, the standard anticoagulants all have significant shortcomings including variable pharmacokinetics, issues with therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The alternative anticoagulants have properties which overcome these shortcomings and prospective clinical trial data are presented supporting the current and future use of these agents in place of the standard anticoagulants.

Laboratory Monitoring of Parenteral Direct Thrombin Inhibitors.

Argatroban and bivalirudin are parenteral direct inhibitors of the activity of thrombin, but, unlike heparin, can inhibit both soluble as well as clot-bound thrombin. These agents do not require antithrombin as a cofactor for activity. The parenteral direct thrombin inhibitors (DTIs) can be used in a variety of settings, including heparin-induced thrombocytopenia (HIT) or an allergy to heparin, and patients requiring anticoagulation for an invasive cardiovascular intervention. Both agents have a relatively short half-life in patients without organ system failure and are typically administered by continuous infusion. Argatroban is primarily eliminated by the liver, while bivalirudin is removed by a combination of proteolytic cleavage by thrombin and renal clearance mechanisms. Several laboratory tests are available for monitoring the anticoagulant effects of the DTIs: the activated partial thromboplastin time (aPTT) and the activated clotting time (ACT) are the most commonly used assays, but on occasion, the thrombin time may be useful. Other coagulation assays such as the dilute thrombin time (dTT), chromogenic anti-IIa assays, and the ecarin clotting time (ECT) can be used. The intensity of anticoagulation with DTIs depends on the indication for use. For patients with HIT, the target aPTT is 1.5 to 3.0 and 1.5 to 2.5 times the patient's baseline value for argatroban and bivalirudin, respectively. DTI anticoagulation used during percutaneous coronary intervention can be measured using ACT. Both DTIs may cause an elevation in the international normalized ratio depending on their plasma concentration. This article will review the use of parenteral DTIs and related laboratory assays for assessing the anticoagulant effect of these drugs.

Rapid and durable response to intravenous immunoglobulin in delayed heparin-induced thrombocytopenia: a case report.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) results in platelet consumption and a virulent thrombotic state, which generally responds to cessation of heparin and initiation of anticoagulation. Rarely, delayed HIT can occur and/or persist after heparin is discontinued. STUDY DESIGN AND METHODS: A 47-year-old male developed delayed HIT with severe thrombocytopenia and thrombosis after cardiac surgery. Thrombocytopenia developed and persisted after heparin cessation and did not improve despite sequential use of argatroban followed by bivalirudin. Treatment with intravenous immunoglobulin (IVIg) was well tolerated and resulted in rapid resolution of thrombocytopenia. RESULTS: There are few case reports on the management of delayed HIT with severe and prolonged thrombocytopenia. The risk for thrombosis and bleeding in the setting of an undefined time course increases uncertainty in management. CONCLUSION: This case, along with others accumulating in the literature, suggest that IVIg may be effective in treating delayed HIT with persistent thrombocytopenia.

Argatroban for Heparin-Induced Thrombocytopenia during Venovenous Extracorporeal Membrane Oxygenation with Continuous Venovenous Hemofiltration.

Patients receiving extracorporeal membrane oxygenation (ECMO) are at risk of circuit thrombosis due to constant contact between blood and the extracorporeal components. Unfractionated heparin has traditionally been used in this setting as a systemic form of anticoagulation to prevent thrombosis of the circuit. However, if a patient develops heparin-induced thrombocytopenia (HIT), an alternative anticoagulant would be required while the patient is maintained on ECMO. Unfortunately, the pharmacokinetic changes induced by ECMO and critical illness may potentially affect optimal drug dosing. In addition, other modalities, such as continuous renal replacement therapy, may further complicate dosing strategies. We report the case of a 27-year-old man with severe acute respiratory distress syndrome who developed HIT while on venovenous ECMO with continuous venovenous hemofiltration. We describe the successful use of an argatroban infusion in this setting at much higher doses than what has previously been reported in the adult literature.

Mannose-binding lectin promotes local microvascular thrombosis after transient brain ischemia in mice.

BACKGROUND AND PURPOSE: Several lines of evidence support the involvement of mannose-binding lectin (MBL) in stroke brain damage. The lectin pathway of the complement system facilitates thrombin activation and clot formation under certain experimental conditions. In the present study, we examine whether MBL promotes thrombosis after ischemia/reperfusion and influences the course and prognosis of ischemic stroke. METHODS: Middle cerebral artery occlusion/reperfusion was performed in MBL-deficient (n=85) and wild-type (WT; n=83) mice, and the brain lesion was assessed by MRI at days 1 and 7. Relative cerebral blood flow was monitored up to 6 hours after middle cerebral artery occlusion with laser speckle contrast imaging. Fibrin(ogen) was analyzed in the brain vasculature and plasma, and the effects of thrombin inhibitor argatroban were evaluated to assess the role of MBL in thrombin activation. RESULTS: Infarct volumes and neurological deficits were smaller in MBL knockout mice than in WT mice. Relative cerebral blood flow values during middle cerebral artery occlusion and at reperfusion were similar in both groups, but decreased during the next 6 hours in the WT group only. Also, the WT mice showed more fibrin(ogen) in brain vessels and a better outcome after argatroban treatment. In contrast, argatroban did not improve the outcome in MBL knockout mice. CONCLUSIONS: MBL promotes brain damage and functional impairment after brain ischemia/reperfusion in mice. These effects are secondary to intravascular thrombosis and impaired relative cerebral blood flow during reperfusion. Argatroban protects WT mice, but not MBL knockout mice, emphasizing a role of MBL in local thrombus formation in acute ischemia/reperfusion.

[Recipient of living kidney transplantation during which heparin-induced thrombocytopenia (HIT) was suspected: a case report].

A 67-year-old woman with a diabetic renal failure was scheduled for a living kidney transplantation. Heparin was first used during hemodialysis 5 days before operation. Thrombocytopenia was found immediately after induction of general anesthesia, and the diagnosis of HIT was wade based on clinical symptom and 4 T's scoring. The surgery was continued because of the progress of donor surgery. Argatoroban was administered based on APTT measurement as an anticoagulation therapy during and after the operation. Although deep vein thrombosis was found 13 days after the operation, the transplanted kidney was established successfully. It is necessary to take a great caution in HIT development after heparin use.

Therapeutic administration of the direct thrombin inhibitor argatroban reduces hepatic inflammation in mice with established fatty liver disease.

Thrombin generation is increased in patients with nonalcoholic fatty liver disease (NAFLD) and in mouse models of diet-induced obesity. Deficiency in the thrombin receptor protease activated receptor-1 reduces hepatic inflammation and steatosis in mice fed a Western diet. However, it is currently unclear whether thrombin inhibitors can modify the pathogenesis of established NAFLD. We tested the hypothesis that thrombin inhibition could reverse hepatic steatosis and inflammation in mice with established diet-induced NAFLD. Low-density lipoprotein receptor-deficient LDLr(-/-) mice were fed a control diet or a Western diet for 19 weeks. Mice were given the direct thrombin inhibitor argatroban ∼15 mg/kg/day or its vehicle via a miniosmotic pump for the final 4 weeks of the study. Argatroban administration significantly reduced hepatic proinflammatory cytokine expression and reduced macrophage and neutrophil accumulation in livers of mice fed a Western diet. Argatroban did not significantly impact hepatic steatosis, as indicated by histopathology, Oil Red O staining, and hepatic triglyceride levels. Argatroban reduced serum triglyceride and cholesterol levels in mice fed a Western diet. Argatroban reduced both α-smooth muscle actin expression and Type 1 collagen mRNA levels in livers of mice fed a Western diet, indicating reduced activation of hepatic stellate cells. This study indicates that therapeutic intervention with a thrombin inhibitor attenuates hepatic inflammation and several profibrogenic changes in mice fed a Western diet.

High-dose argatroban therapy for stroke: novel treatment for delayed treatment and the recanalization mechanism.

BACKGROUND: There has been little effective treatment in patients with cerebral infarction at >24 hours after onset. We assessed the effects of high-dose argatroban therapy in delayed administration, and investigated the mechanism based on our clinical findings. METHODS: Argatroban 30 mg was first administered for 15 minutes intravenously, and then 90 mg for 60 minutes followed by 60 mg for 60 minutes were infused continuously. The change of vascular obstruction caused by the treatment was assessed with magnetic resonance angiography. RESULTS: In 4 patients studied, high-dose argatroban resulted in 100% recanalization of occluded vessels (5/5), even though argatroban was administrated >24 hours after onset. On the other hand, when an inadequate dose of argatroban was administered, a hemorrhage was identified. This supports our hypothesis that high-dose argatroban promotes recanalization by deactivating thrombin and exerting an anticoagulant effect on the vascular endothelium. CONCLUSIONS: High-dose argatroban is an effective treatment for cerebral infarction and offers a novel therapeutic approach for delayed hospitalized patients at >24 hours after onset. Additional studies are necessary to identify the cellular and molecular mechanisms and determine the adequate dose in order to reduce risks of complication.