Potential Role of Direct Oral Anticoagulants in the Management of Heparin-induced Thrombocytopenia

Heparin-Induced Thrombocytopenia (HIT) in the Direct Oral Anticoagulants (DOAC) Era

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an uncommon complication of heparin therapy with significant risk for severe morbidity and mortality. We investigated the role and outcome of direct oral anticoagulants (DOACs) for the management of HIT.

METHODS

After institutional review board (IRB) approval, a retrospective review was performed identifying all patients with positive HIT serotonin-release assays between 2020 and 2022 at two hospitals. The demographic and clinical variables were collected as follows: initial anticoagulant, dosing and indication, interval before onset of HIT, thrombotic complications, platelet nadir and recovery, direct thrombin inhibitor (DTI) and DOAC usage, and clinical outcomes.

RESULTS

15 patients were included in the study. 8 underwent a vascular procedure, 3 had cardiac surgery, 1 patient had both and was included in both groups, and 5 patients had either noncardiac, nonvascular surgery, or no surgery. 14 patients received unfractionated heparin (93% with therapeutic dosing), and 1 received prophylactic enoxaparin prior to diagnosis of HIT. The average time to diagnosis of HIT was 10.77 days after initial anticoagulation. In-hospital mortality was 27%, related to Covid-19 infection (3/4) and intracranial hemorrhage (1/4). 40% developed thrombosis (67% venous, 33% arterial) after the diagnosis of HIT. 8/11 survivors were discharged on a DOAC. With DOAC therapy, platelet counts rebounded to an average of 265K ( ± 104.6 K) within an average of 2.3 days and 364K ( ± 273.9 K) within 30 days after initiation of a DOAC. No recurrent thrombosis occurred after DOAC administration and only one patient had persistent thrombocytopenia within 30 days.

CONCLUSIONS

Mortality and thrombosis (arterial and venous) are common complications in patients diagnosed with HIT. In patients who survive to discharge, DOACs are the most common discharge antithrombotic agent, with low rates of recurrent thrombosis and thrombocytopenia.

Heparin-induced thrombocytopenia in lower extremity free tissue transfers

BACKGROUND

Heparin-induced thrombocytopenia (HIT) an immunologically mediated reaction to heparin products, can lead to severe thrombocytopenia and potentially life-threatening thrombotic events. In microsurgery, a missed or delayed diagnosis of HIT can cause complications requiring revision operations, flap loss, or limb loss. Surgeons must remain vigilant for this uncommon yet potentially devastating condition and keep abreast of management strategies.

METHODS

CPT and ICD-10 codes in electronic medical records were used to collect demographic information, clinical courses, and outcomes for patients with a HIT diagnosis who underwent lower extremity free tissue transfer in one institution.

RESULTS

The authors' institution performed 415 lower extremity free flaps in 411 patients during the 10-year study period. Flap salvage rate was 71% for compromised lower extremity flaps without HIT, and 25% in those with HIT. Four patients (four flaps) met study inclusion criteria during the study period. Three of the four flaps failed and were later debrided; one was rescued after a takeback for anastomosis revision. Two patients successfully underwent a delayed second free flap procedure after recovery, and one was salvaged with a pedicled muscle flap.

CONCLUSIONS

Surgeons should monitor for HIT by establishing coagulation panel and platelet count baselines and trending these values in the early post-operative period for patients treated with heparin products. The 4T score can be used to screen for HIT with high clinical suspicion. Arterial thrombosis or poor flap perfusion despite sound microvascular technique could suggest HIT. Surgical and medical management including strict heparin avoidance can prevent adverse events for these patients.

A Review of the Past, Present and Future of Cancer-associated Thrombosis Management

Venous thromboembolism (VTE) can have a significant impact on the management, quality of life and mortality of patients with cancer. VTE occurs in 5-20% of patients with cancer, and malignancy is associated with up to 25% of all VTE. It is the second leading cause of death in ambulatory patients with cancer who are receiving chemotherapy. Increased rates of cancer-associated thrombosis are attributed to improved patient survival, increased awareness, surgery, antineoplastic treatments and the use of central venous access devices. Many factors influence cancer-associated thrombosis risk and are broadly categorized into patient-related, cancer-related and treatment-related risks. Direct-acting oral anticoagulants have shown themselves to be at least as effective in preventing recurrent VTE in patients with cancer with symptomatic and incidental VTE. This has led to a change in treatment paradigms so that direct-acting oral anticoagulants are now considered first-line agents in appropriately selected patients. In this article, we review the prior and recent landmark studies that have directed the treatment of cancer-associated thrombosis, and discuss specific factors that affect management as well as future treatment considerations.

Acute lower limb ischemia caused by vaccine-induced immune thrombotic thrombocytopenia: focus on perioperative considerations for 2 cases

BACKGROUND

ChAdOx1 nCoV-19 (AstraZeneca) and Ad26COV2.S (Johnson & Johnson/Janssen) adenoviral vector vaccines have been associated with vaccine-induced immune thrombotic thrombocytopenia (VITT). Arterial thrombosis and acute limb ischemia have been described in a minority of patients with VITT. These patients usually need a revascularization, but they potentially are at a higher risk of complications. Optimal perioperative care of patients undergoing vascular surgery in acute VITT is unknown and important considerations in such context need to be described.

CASES PRESENTATIONS

We report 2 cases of VITT presenting with acute limb ischemia who needed vascular surgery and we describe the multidisciplinary team decisions for specific treatment surrounding the interventions. Both patients' platelet counts initially increased after either intravenous immune globulin (IVIG) or therapeutic plasma exchange (TPE). None received platelet transfusion. They both received argatroban as an alternative to heparin for their surgery. Despite persistent positivity of anti-platelet factor 4 (PF4) antibodies and serotonin-release assay with added PF4 (PF4-SRA) in both patients, only one received a repeated dose of IVIG before the intervention. Per- and post-operative courses were both unremarkable.

CONCLUSION

In spite of persistent anti-PF4 and PF4-SRA positivity in the setting of VITT, after platelet count improvement using either IVIG or TPE, vascular interventions using argatroban can show favorable courses. Use of repeated IVIG or TPE before such interventions still needs to be defined.

Recent Advances in Anticoagulant Treatment of Immune Thrombosis: A Focus on Direct Oral Anticoagulants in Heparin-Induced Thrombocytopenia and Anti-Phospholipid Syndrome

For more than 10 years, direct oral anticoagulants (DOACs) have been increasingly prescribed for the prevention and treatment of thrombotic events. However, their use in immunothrombotic disorders, namely heparin-induced thrombocytopenia (HIT) and antiphospholipid syndrome (APS), is still under investigation. The prothrombotic state resulting from the autoimmune mechanism, multicellular activation, and platelet count decrease, constitutes similarities between HIT and APS. Moreover, they both share the complexity of the biological diagnosis. Current treatment of HIT firstly relies on parenteral non-heparin therapies, but DOACs have been included in American and French guidelines for a few years, providing the advantage of limiting the need for treatment monitoring. In APS, vitamin K antagonists are conversely the main treatment (+/− anti-platelet agents), and the use of DOACs is either subject to precautionary recommendations or is not recommended in severe APS. While some randomized controlled trials have been conducted regarding the use of DOACs in APS, only retrospective studies have examined HIT. In addition, vaccine-induced immune thrombotic thrombocytopenia (VITT) is now a part of immunothrombotic disorders, and guidelines have been created concerning an anticoagulant strategy in this case. This literature review aims to summarize available data on HIT, APS, and VITT treatments and define the use of DOACs in therapeutic strategies.

Direct Oral Anticoagulants as Successful Treatment of Heparin-Induced Thrombocytopenia: A Parisian Retrospective Case Series

Background: Heparin-induced thrombocytopenia (HIT) is a prothrombotic life-threatening disorder caused by an adverse reaction to heparin exposure. In this context, it is imperative to stop heparin immediately and to replace it by a non-heparin anticoagulant therapy. Despite their advantages, the use of direct oral anticoagulants (DOACs) is only emerging for HIT treatment, and their use remains rare. Objective: To improve our knowledge on the emerging role of DOACs as treatment of HIT and give an overview of our local practices in this context. Patients/Methods: This is a multi-centric retrospective case series of HIT patients referred to our Parisian pharmacovigilance network and treated with DOACs. Results: We report the cases of seven patients from four healthcare centers, diagnosed with HIT (4T score ≥ 4, positive anti-PF4/heparin immunoassay and positive serotonin-release assay) and treated with DOACs. After a few days on substitutive parenteral treatment (n = 6) or directly at HIT diagnosis (n = 1), these patients were treated with either rivaroxaban (n = 6) or apixaban (n = 1) during acute HIT phase. Mean time to platelet count recovery after heparin discontinuation was 3.3 days (range 3-5). No patient experienced major or clinically relevant non-major bleeding or thrombosis that could be related to DOAC treatment during follow-up. Conclusions: Our cases studies are consistent with recent guidelines credit to the potential and safe use of DOAC during acute HIT in clinically stable patients.

Heparin-induced thrombocytopenia: pathophysiology, diagnosis and treatment

Introduction: Immune-mediated heparin-induced thrombocytopenia (HIT) is an infrequent complication following heparin exposure but with potentially fatal outcome due to thrombotic complications. Prompt suspension of heparin is necessary if HIT is suspected, followed by initiation of non-heparin anticoagulant therapy.Areas covered: In this review, the pathophysiology and challenges in diagnosing HIT are elucidated. Current and emerging treatment options are discussed with special focus on parenteral thrombin inhibitors (argatroban, bivalirudin), parenteral factor Xa inhibitors (danaparoid, fondaparinux) and direct oral anticoagulants (DOACs [rivaroxaban, apixaban, dabigatran]) including dosing strategies for DOACs. The database PubMed was employed without time boundaries.Expert opinion: Only argatroban holds regulatory approval for HIT treatment in both U.S. and Europe. This treatment is, however, challenged by the need for close monitoring and high costs. Fondaparinux has been increasingly used for off-label treatment and during recent years, evidence for the use of DOACs has emerged. Preliminary results from observational studies hold promise for future use of DOACs in the acute and subacute phase of HIT. However, so far, the use of DOACs in acute HIT should be reserved for clinically stable patients without severe thrombotic complications. Importantly, both fondaparinux and DOAC use is contraindicated in severe renal insufficiency.

Superior outcomes with Argatroban for heparin-induced thrombocytopenia: a Bayesian network meta-analysis

Background Argatroban, lepirudin, desirudin, bivalirudin, and danaparoid are commonly used to manage heparin-induced thrombocytopenia related complications. However, the most suitable drug for this condition still remains controversial. Aim of the review This Bayesian network meta-analysis study compared the most common anticoagulant drugs used in the management of heparin-induced thrombocytopenia. Method All clinical trials comparing two or more anticoagulant therapies for suspected or confirmed heparin-induced thrombocytopenia were considered for inclusion. Studies concerning the use of heparins or oral anticoagulants were not considered. Data concerning hospitalisation length, thromboembolic, major, and minor haemorrhagic events, and mortality rate were collected. The network analyses were made through the STATA routine for Bayesian hierarchical random-effects model analysis with standardised mean difference (SMD) and log odd ratio (LOR) effect measures. Results Data from a total of 4338 patients were analysed. The overall mean age was 62.31 ± 6.6 years old. Hospitalization length was considerably shorter in favour of the argatroban group (SMD: − 1.70). Argatroban evidenced the lowest rate of major (LOR: − 1.51) and minor (LOR: − 0.57) haemorrhagic events. Argatroban demonstrated the lowest rate of thromboembolic events (LOR: 0.62), and mortality rate (LOR: − 1.16). Conclusion Argatroban performed better overall for selected patients with HIT. Argatroban demonstrated the shortest hospitalization, and lowest rate of haemorrhages, thromboembolisms, and mortality compared to bivalirudin, lepirudin, desirudin, and danaparoid.

Review of Medical Therapies for the Management of Pulmonary Embolism

Traditionally, the management of patients with pulmonary embolism has been accomplished with anticoagulant treatment with parenteral heparins and oral vitamin K antagonists. Although the administration of heparins and oral vitamin K antagonists still plays a role in pulmonary embolism management, the use of these therapies are limited due to other options now available. This is due to their toxicity profile, clearance limitations, and many interactions with other medications and nutrients. The emergence of direct oral anticoagulation therapies has led to more options now being available to manage pulmonary embolism in inpatient and outpatient settings conveniently. These oral therapeutic options have opened up opportunities for safe and effective pulmonary embolism management, as more evidence and research is now available about reversal agents and monitoring parameters. The evolution of the pharmacological management of pulmonary embolism has provided us with better understanding regarding the selection of anticoagulants. There is also a better understanding and employment of anticoagulants in pulmonary embolism in special populations, such as patients with liver failure, renal failure, malignancy, and COVID-19.

Rivaroxaban Treatment for Heparin-Induced Thrombocytopenia: A Case Report and a Review of the Current Experience

Heparin-induced thrombocytopenia is a life-threatening complication of exposure to heparin. Heparin-induced thrombocytopenia results from an autoantibody directed against platelet factor 4 in complex with heparin. Heparin-induced thrombocytopenia is traditionally treated with bivalirudin, argatroban, danaparoid, or fondaparinux. Recently, direct oral anticoagulants administration to treat heparin-induced thrombocytopenia has been reported. Direct oral anticoagulants do not cause platelet activation in the presence of heparin-platelet factor 4 antibodies, nor do they provoke autoantibody production. Direct oral anticoagulants offer advantages such as consistent and predictable anticoagulation, oral administration with good patient compliance, and a good safety profile. We report a case of heparin-induced thrombocytopenia with deep venous thrombosis successfully treated with rivaroxaban and review the current experience with rivaroxaban for the treatment of heparin-induced thrombocytopenia.

Prevention and Treatment of Venous Thromboembolism Associated with Coronavirus Disease 2019 Infection: A Consensus Statement before Guidelines

Coronavirus disease 2019 (COVID-19) has caused a global pandemic in just a few months, causing millions infected. Nearly 20% of COVID-19 patients present severe coagulation abnormalities, which may occur in almost all of the severe and critical ill COVID-19 cases. Concomitant venous thromboembolism (VTE), a potential cause of unexplained deaths, has been frequently reported in COVID-19 cases, but its management is still challenging due to the complexity between antithrombotic therapy and coagulation disorders. Based on frontline practical experience and comprehensive literature review, here a panel of experts and physicians from China and Europe developed an evidence and opinion-based consensus on the prophylaxis and management of VTE associated with COVID-19. This statement aims for clinicians treating COVID-19 and provides practical recommendations in detailed situations, for example, how to choose thromboprophylactic measures for patients with diverse severity of disease and bleeding risk, or which kind of anticoagulant should be prescribed. With limited experience on COVID19-associated VTE, this expert consensus statement should be helpful for clinicians worldwide with specific suggestions.