Antibodies to platelet factor 4-heparin after cardiopulmonary bypass in patients anticoagulated with unfractionated heparin or a low-molecular-weight heparin clinical implications for heparin-induced thrombocytopenia

• Published in: Circulation (New York, N.Y.) N.Y.), 1999-05, Vol.99 (19), p.2530-2536
• Main Authors: POUPLARD, C, MAY, M.-A, IOCHMANN, S, AMIRAL, J, VISSAC, A.-M, MARCHAND, M, GRUEL, Y
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Anesthesia; Anesthesia depending on type of surgery; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Antibodies - blood; Antibodies - immunology; Biological and medical sciences; Cardiopulmonary Bypass; Drug toxicity and drugs side effects treatment; Female; Heparin - adverse effects; Heparin - immunology; Heparin - therapeutic use; Heparin, Low-Molecular-Weight - adverse effects; Heparin, Low-Molecular-Weight - therapeutic use; Humans; Male; Medical sciences; Middle Aged; Pharmacology. Drug treatments; Platelet Factor 4 - immunology; Postoperative Complications - prevention & control; Thoracic and cardiovascular surgery. Cardiopulmonary bypass; Thrombocytopenia - chemically induced; Thrombocytopenia - immunology; Toxicity: blood
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.99.19.2530

Cardiopulmonary bypass (CPB) induces platelet activation with release of platelet factor 4 (PF4), and patients are exposed to high doses of heparin (H). We investigated whether this contributes to the development of antibodies to H-PF4 and heparin-induced thrombocytopenia (HIT). CPB was performed with unfractionated heparin (UFH) in 328 patients. After surgery, patients received UFH (calcium heparin, 200 IU. kg-1. d-1) (group 1, n=157) or low-molecular-weight heparin (LMWH, Dalteparin, 5000 IU once daily) (group 2, n=171). Eight days after surgery, antibodies to H-PF4 were present in 83 patients (25.3%), 46 in group 1 and 37 in group 2 (P=0.12). Most patients (61%) had IgG1 to H-PF4, but only 8 samples with antibodies induced platelet activation with positive results on serotonin release assay. HIT occurred in 6 patients in group 1, but no thrombocytopenia was observed in subjects receiving LMWH, although 2 had high levels of antibodies with positive serotonin release assay results. When antibodies to H-PF4 were present, mean platelet counts were lower only in patients with FcgammaRIIA R/R131 platelets. These results provide evidence that the development of antibodies to H-PF4 after CPB performed with UFH is not influenced by the postoperative heparin treatment. The antibodies associated with high risk of HIT are mainly IgG1, which is present at high titers in the plasma of patients continuously treated with UFH.