Heparin Reexposure in Patients With a History of Heparin-Induced Thrombocytopenia

Objectives: Patients with a history of heparin-induced thrombocytopenia (HIT), who require subsequent anticoagulation, have limited options. Rechallenge with unfractionated heparin (UFH) has been reported but may be associated with a risk of recurrence of HIT. The objective of this study was to determine the safety of heparin reexposure in patients with a history of HIT. Methods: Using several search terms, all cases of heparin reexposure in patients with HIT indexed in MEDLINE (English language only) by June 2014 were reviewed. The bibliography of each relevant article was searched for additional reports. In cases of multiple reexposures, each reexposure was identified as a separate instance of reexposure during analysis. Results: A total of 136 patients with a history of HIT had 141 instances of heparin reexposure. Cardiac (76%) and vascular surgeries (11%) were the most common indications. Antiplatelet factor 4/heparin antibodies were positive in 63% of evaluable cases before reexposure. Preexposure plasma exchange (11%) and postexposure nonheparin anticoagulants (63%) were frequently utilized. Complications with heparin reexposure included recurrence of HIT (2.1%, 95% confidence interval 0.73%-6.07%) and bleeding (2.1%). Conclusion: Intraoperative heparin reexposure in patients with a history of HIT has a small risk of developing HIT recurrence. The use of preexposure plasma exchange in patients with positive antiplatelet factor 4/heparin antibody and postexposure nonheparin anticoagulants arguably may have reduced the risk of recurrence of HIT.