Use of Plasmapheresis in Heparin Induced Thrombocytopenia in Patients Undergoing Urgent Cardiac Surgery

Document Type

Conference Proceeding

Publication Date

11-29-2023

Publication Title

Am J Clin Pathol

Abstract

Heparin Induced Thrombocytopenia (HIT) is a potentially lifethreatening but uncommon disease process characterized by IgG antibodies that recognize platelet factor 4/heparin immune complexes causing thrombocytopenia and thrombosis. Although therapeutic plasmapheresis (PLEX) appears to be effective, protocols regarding how and when to institute PLEX remain elusive. At our institution, we put together a standardized approach to assess the interventional success across patients that included 1 plasmapheresis procedure per day over 4 days, processing one plasma volume and using thawed plasma as the replacement fluid. Treatment effectiveness was evaluated by pre- and post-interventional HIPA OD levels and platelet count. Treatment aim was to decrease the HIPA OD to less than 0.6 and obtain a normal platelet count. The aim of this study was to design a protocol for PLEX to address urgent need for patients with HIT for which heparin is planned for intraoperative cardiac surgery requiring cardiopulmonary bypass (CPB) anticoagulation. We retrospectively examined the medical records of 2 HIT-positive patients who underwent PLEX prior to cardiac surgery at our large quaternary care hospital. Both patients had a 4Ts score of 5, with a medium probability of disease. One patient's HIT was confirmed by a positive serotonin release assay (SRA). The second patient had persistently negative confirmatory test but was deemed clinical HIT. The first patient is a 53-year-old female, who was admitted for mitral valve replacement, aortic valve replacement, and tricuspid valve repair. She was confirmed HIT by positive SRA. Three sessions of PLEX were performed on consecutive days. Her HIPA (heparin induced platelet antibody) O.D. value decreased from 1.925 to 0.534 and platelet counts normalized. The second patient is a 73-year-old male, who was admitted for LVAD implantation and LV thrombus resection. Two sessions of PLEX were performed on consecutive days. His HIPA O.D. value deceased from 1.261 to < 0.4 (negative) and platelet counts normalized. For both patients, the last PLEX procedure was performed the day of surgery, and the cardiac surgical procedure was completed successfully. Based on these 2 patients, we have proposed a protocol for PLEX in HIT patients as follows: daily plasmapheresis x 4 days will be performed until the OD has decreased to less than 0.6 and platelet count has normalized. Each plasmapheresis will consist of the processing of one plasma volume, using thawed plasma as the replacement fluid. The last plasmapheresis will occur on the day of surgery prior to surgery. Further assessment will be performed if the targeted parameters have not been met by the 4th plasmapheresis procedure. In conclusion, we present 2 patients with HIT who benefitted from PLEX prior to cardiac surgery under CPB. We will adopt the protocol used for these 2 patients as our standard of practice moving forward.

Volume

160

First Page

S115

Last Page

S116

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