Registrar Internal Medicine, The Prince Charles Hospital Brisbane, Queensland, Australia
Background: Patients diagnosed with Heparin induced thrombocytopenia (HIT) require early commencement of non-heparinoid anticoagulants to reduce thrombotic complications. Additional information on clinical outcomes associated with non-heparin anticoagulant use will add to available literature for HIT management.
Aims: Assess rate of thrombosis, platelet recovery, and major bleeding across non-heparin anticoagulants used in HIT treatment.
Methods: Retrospective review of all patients treated for HIT at a tertiary hospital from 1 January,2010 to 30 June,2023. Clinical data were collected via pre-set questionnaires following Ethics approval. Student t-test was used to compare continuous data.
Results: Incidence of HIT was low at 57/742 (7.7%) patients screened, dominated by cardiothoracic surgery and critically ill patients (49/57). Symptomatic thrombosis and thromboses at multiple sites were common, with high thrombus burden (Table 1). Assay titre did not reliably predict for thrombosis (Figure 1). 4/57 patients had recurrent thrombosis on therapeutic non-heparin anticoagulation and filter thrombus was seen in 2/6 IVC filters deployed to protect the pulmonary vascular bed. Mean platelet recovery (3 to 5 days) was similar with all non-heparin anticoagulants and 58% achieved normal platelet counts within a week. 2 patients with delayed platelet recovery had undiagnosed myelodysplasia. Bleeding events were mainly associated with surgical intervention. No deaths were directly attributed to HIT, however 2 patients required amputation. 9/57 patients required urgent surgery within 16 days of HIT including 4 transplants.
Conclusion(s): HIT was uncommon but associated with high morbidity both from disease and therapy. Alternate anticoagulation did not eliminate risk of recurrent thrombosis; clinical vigilance is imperative and IVC filter use judicious. Patients without symptomatic thrombosis need Doppler ultrasound regardless of assay titre. Patients requiring cardiac surgical interventions on alternate anticoagulation are at high risk of bleeding, underscoring the need for readily accessible functional assays to reduce unnecessary irreversible anticoagulant exposure in vulnerable patients.
