PB0036 - Clinical and serological follow up of VITT patients treated with heparin and alternative anticoagulation

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Karina Althaus, MD

Physician, Director of Platelet Immunology Lab.
Center for Clinical Transfusion Medicine, University Hospital of Tübingen
Tübingen, Baden-Wurttemberg, Germany

Co-Author(s)

Günalp Uzun, MD

Physician
Center for Clinical Transfusion Medicine, University Hospital of Tübingen
Tübingen, Baden-Wurttemberg, Germany
BL

Beate Luz

Medical Doctor
Institute of Transfusion Medicine, Klinikum Stuttgart
Stuttgart, Baden-Wurttemberg, Germany
MW

Marc Wolf

Professor
Department of Neurology, Klinikum Stuttgart
Stuttgart, Baden-Wurttemberg, Germany
HH

Hans Henkes

Professor
Department of Neuroradiology, Klinikum Stuttgart
Stuttgart, Baden-Wurttemberg, Germany
Tamam Bakchoul, MD

Medical Director
Center for Clinical Transfusion Medicine, University Hospital of Tübingen
Tübingen, Baden-Wurttemberg, Germany

Background: Vaccine induced thrombotic thrombocytopenia (VITT) is a rare but severe complication following vaccination with ChAdOx1 nCoV-19. Antibodies directed against platelet factor 4 (PF4) are thought to be responsible for platelet activation and subsequent thromboembolic events in these patients. Because of the similarities between heparin-induced thrombocytopenia (HIT) and VITT heparin was avoided but the risk of thrombosis in VITT upon heparin administration remains unclear.

Aims: To assess the impact of heparin used as initial anticoagulants to treat VITT.

Methods: We prospectively analyzed follow up data from 4 patients with confirmed VITT patients (3 women and 1 men; median age, 44 years [range, 22 to 62 years]). ELISA and functional VITT testing was performed at each time point.

Results: The patients’ clinical symptoms started between days 4 and 17 after first vaccination with ChAdOx1 nCoV-19. All patients presented with thrombocytopenia and thromboembolic events (amaurosis fugax and peripheral thrombosis and venous sinus thrombosis). The follow-up duration ranged between 8 weeks and 9 months. No additional thromboembolic event or disease progression occured in any patient. A recovery in platelet count was monitored in all four patients within 10 days after starting treatment (heparin or alternative anticoagulation combined with IVIG). In both patients who were treated with heparin, anti-PF4 antibodies were not detectable after 3 and 19 weeks respectively. All 4 patients received mRNA-based vaccine as second vaccination against SARS CoV2. No significant drop in platelet count or new thromboembolic complication was observed.

Conclusion(s): In the treatment of VITT, early beginning of anticoagulation with close follow-up of the platelet count and thrombosis signs seem to be more important than the choice of anticoagulant. Subsequent vaccination with an mRNA vaccine appears to be safe in VITT patients.