An Open-Label, Single-Arm, Pilot Intervention Study to Assess the Efficacy and Safety of Apixaban in Heparin-Induced Thrombocytopenia

Management of Heparin-Induced Thrombocytopenia: A Contemporary Review

Heparin-induced thrombocytopenia (HIT) is a life- and limb-threatening immune-mediated emergency classically associated with heparin therapy. This review focuses on type II HIT, characterized by the development of antibodies against platelet-factor 4 (PF4) bound to heparin after exposure, causing life-threatening thrombocytopenia, arterial thrombosis, and/or venous thrombosis. The high morbidity and mortality rates emphasize the need for early recognition and urgent intervention with discontinuation of heparin and initiation of non-heparin anticoagulation. We discuss the management of HIT with an emphasis on recent developments: (i) incorporating the phases of HIT (i.e., suspected, acute, subacute A and B, and remote) into its management, categorized according to platelet count, immunoassay, and functional assay results and (ii) direct-acting oral anticoagulants (DOACs), which are increasingly used in appropriate cases of acute HIT (off-label). In comparison to parenteral options (e.g., bivalirudin and danaparoid), they are easier to administer, are more cost-effective, and obviate the need for transition to an oral anticoagulant after platelet recovery. We also identify the knowledge gaps and suggest areas for future research.

Results of an international survey of opinions on the definitions and treatments for heparin-induced thrombocytopenia: communication from the ISTH SSC Subcommittee on Platelet Immunology

Heparin-induced thrombocytopenia (HIT) is rare, affecting fewer than 1 in 1500 hospital admissions. Despite the increasing adoption of new therapies in HIT, such as direct oral anticoagulants and pooled immunoglobulins, there is limited high-quality evidence to guide clinicians. Numerous uncommon presentations of HIT and HIT-like entities have recently been recognized, and a harmonized approach to their classification is required to study them better. We present the results of an international survey of opinions from experts and practitioners in the field of platelet immunology regarding the role of direct oral anticoagulants in HIT, novel definitions of subclassifications of HIT-like platelet factor 4 immune conditions (spontaneous autoimmune HIT, persistent autoimmune HIT, and treatment-refractory HIT), and the role for intravenous immunoglobulins in the treatment paradigm of HIT and these HIT-like conditions. From 102 survey responses, there was broad acceptance of rivaroxaban (74.5%) and apixaban (73.5%) even before platelet recovery, as well as for intravenous immunoglobulin in the management of spontaneous (85.6%), persistent (83.7%), and treatment-refractory HIT (87.4%). With this mandate for harmonizing terminologies and treatment approaches in special situations without robust clinical data owing to their rarity, we plan to conduct a robust survey, establish international consensus, and draft management guidelines for HIT and platelet factor 4 immune diseases in the near future.

Successful Treatment With the Oral Factor Xa Inhibitor Edoxaban in Heparin-Induced Thrombocytopenia With Thrombosis

Heparin-induced thrombocytopenia with thrombosis (HITT) is a rare immune reaction to the drug heparin that causes increased blood clotting, putting patients at risk for arterial and venous thromboembolism which can have severe consequences. We present a case of HITT successfully treated with the direct oral anticoagulant (DOAC), edoxaban. A 56-year-old man had surgery to remove a colorectal mass. After discharge, he developed chest discomfort, shortness of breath, and low oxygen levels and was diagnosed with a right-sided lobar pulmonary embolism. His platelet count dropped, his tests confirmed a diagnosis of HITT, and he was initially treated with fondaparinux. After showing clinical and laboratory improvement, he was switched to edoxaban. Despite being diagnosed with colonic adenocarcinoma during follow-up, the patient's platelet count returned to normal, and he did not experience any more blood clots or serious bleeding events. The use of DOACs like edoxaban as potential therapies for HITT is promising; further research is being conducted to evaluate their effectiveness, safety, and potential benefits for treating this acquired high-risk thrombophilia.