Heparin-Induced Thrombocytopenia in a Patient with Essential Thrombocythemia: A Case Based Update

Heparin-induced thrombocytopenia with very high antibody titer is associated with slower platelet recovery and higher risk of thrombosis

Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by platelet-activating antibodies targeting platelet factor 4 (PF4) and heparin complex. A higher antibody titer is reflected in a higher optical density (OD) by enzyme-linked immunosorbent assay for heparin-PF4 antibodies. This single-institution retrospective study of 116 HIT patients examined the effect of heparin-PF4 OD on time to platelet recovery, vascular thrombosis, and in-hospital mortality. Patients were divided into 3 cohorts based on heparin-PF4 OD: cohort 1 had an OD ≥ 2 and ≤ 2.4, cohort 2 had an OD > 2.4 and ≤ 2.8, and cohort 3 had an OD > 2.8. A higher OD titer was associated with significantly increased time to platelet recovery when compared between cohorts 1 versus 2 (HR = 0.599, p = 0.0221) and 1 versus 3 (HR = 0.515, p = 0.0014), as well as an increased risk of thrombosis (79.4%-cohort 3 vs 53.8%-cohort 2 vs 46.1%-cohort 1, p = 0.04), but had no impact on mortality (2.62-alive vs 2.65-deceased, p = 0.7432). A higher OD titer can inform risk assessment and support decision-making in HIT patients; however, prospective studies are needed to further clarify the impact of heparin-PF4 OD on outcomes.

Percutaneous coronary intervention in a patient with heparin resistance due to essential thrombocythaemia: a case report

Background 

Coronary artery disease is uncommon in patients with essential thrombocythaemia (ET); therefore, no treatment strategies have been established.

Case summary 

A 68-year-old man visited our hospital with worsening effort angina complicated with ET. Coronary angiography (CAG) revealed moderate stenosis of the left main trunk and left anterior descending artery (LAD). We planned to perform percutaneous coronary intervention (PCI) only after the patient’s platelet count had fallen below 600 000/μL. Platelet factor 4 levels were markedly elevated (355.0 ng/mL; the normal range is <20 ng/mL). We observed a de novo lesion in the proximal left circumflex artery and stenosis progression in the LAD at the time of the PCI, neither of which had been detected at the previous CAG. During the PCI procedure, argatroban was infused to maintain the activated clotting time (ACT) above 250 s. The PCI was performed successfully without any complications. Follow-up CAG showed no restenosis, and no bleeding complications were observed during the course.

Discussion 

In patients with ET, it may be useful to measure platelet factor 4 before PCI and to monitor ACT during the procedure. When heparin resistance is suspected based on blood coagulation tests, infusion of direct thrombin inhibitor during PCI may be considered, with anticoagulation monitoring by ACT.

Autoimmune Heparin-Induced Thrombocytopenia: Treatment Obstacles and Challenging Length of Stay

Patient: Male, 55

Final Diagnosis: Auto-immune heparin thrombocytopenia -Treatment obstacles and challenging length of stay

Symptoms: Thrombocytopenia • thrombosis

Medication: —

Clinical Procedure: IVIG

Specialty: Hematology