Replacement of unfractionated heparin by low-molecular-weight heparin for postorthopedic surgery antithrombotic prophylaxis lowers the overall risk of symptomatic thrombosis because of a lower frequency of heparin-induced thrombocytopenia

Abstract

References

Anti–platelet factor 4/heparin antibodies in orthopedic surgery patients receiving antithrombotic prophylaxis with fondaparinux or enoxaparin

“…Our hypothesis was that treatment with the pentasaccharide, fondaparinux, would not be associated with formation of anti-PF4/heparin antibodies. In contrast, we expected some patients receiving LMWH to develop anti-PF4/heparin antibodies, 7,8,29,30 and potentially even HIT. This hypothesis was based on previous observations indicating that although heparin molecules of tetrasaccharide length or greater bind to PF4, 10 they do not create the antigens recognized by HIT antibodies unless they are at least about 8 to 10 saccharides in length or greater.…”

“…7,8,28 A lower frequency of immunization 7,8,29,30 is believed to be a major factor that explains a lower risk of HIT with LMWH, particularly because both UFH and LMWH preparations yield similar magnitude of reactivity in vitro in assays used to detect the antibodies that cause HIT. 7,20,31 This corresponds to the known risk of persisting or recurring thrombocytopenia if LMWH is used to treat HIT caused by UFH.…”

“…5,6 The frequency of HIT is about 3% to 5% in orthopedic surgery patients treated with unfractionated heparin (UFH) but is less than 1% in patients receiving LMWH. 7,8 The reduced risk of HIT could be because LMWH forms smaller, and presumably less immunogenic, complexes with PF4, compared with UFH. 9 Although the pentasaccharide, fondaparinux, may bind to PF4 (based on evidence that PF4 binds to sulfated oligosaccharides as small as a tetrasaccharide 10 ), its length is shorter than the 10 to 12 saccharides reported for binding to PF4 to result in strong reactivity with HIT antibodies.…”

Treatment and Prevention of Heparin-Induced Thrombocytopenia

“…13,14,[21][22][23][24] Women have approximately twice the risk of developing HIT as men. 18 Table 2 [25][26][27][28][29][30][31][32][33][34][35] presents the incidence of HIT in various patient populations.…”

Rivaroxaban para el tratamiento de la trombocitopenia inducida por heparina. Caso clínico

“…Asimismo, el riesgo de pacientes postoperados de cirugía cardíaca y traumatológica es mayor que en otros pacientes. Se describe una incidencia de 1 a 5% para uso de HNF y 0,1 a 1% para uso de HBPM 7,8,9 .…”