PREVALENCE OF HEPARIN-ASSOCIATED ANTIBODIES WITHOUT THROMBOSIS IN PATIENTS UNDERGOING CARDIOPULMONARY BYPASS-SURGERY

Background Patients with cardiovascular disease almost invariably rece ive heparin before cardiopulmonary bypass surgery, which places them a t risk of developing heparin-associated antibodies with a risk of thro mboembolic complications. This study was designed to determine the pre valence of heparin-induced antibodies in patients before and after car diopulmonary bypass surgery. Methods and Results Plasma from 111 patie nts was tested before surgery and 5 days after surgery for heparin-dep endent platelet-reactive antibodies with a C-14-serotonin-release assa y (SRA) and for antibodies to heparin/platelet factor 4 complexes with an ELISA. Heparin exposure after surgery was minimized. Heparin-depen dent antibodies were detected before surgery in 5% of patients with SR A and 19% of patients with ELISA. By the fifth postoperative day, ther e was a marked increase in patients positive on the SRA or ELISA (13% and 51%, respectively; P<.01 for each). Patients who had received hepa rin therapy earlier in their hospitalization were more likely to have a positive ELISA before surgery (35%; P=.017) and a positive ELISA (68 %; P=.054) or SRA (30%; P=.002) after surgery. However, there was no d ifference in the prevalence of thrombocytopenia or thromboembolic even ts between the antibody-positive and -negative groups. Conclusions App roximately one fifth of patients undergoing cardiopulmonary bypass sur gery have heparin-induced platelet antibodies detectable before the pr ocedure as a result of prior heparin exposure, and many more develop a ntibodies after surgery. The absence of an association between these a ntibodies and thromboembolic complications in this study may be, in pa rt, attributable to careful avoidance of heparin after surgery. The hi gh prevalence of heparin-induced antibodies in this setting suggests t hat these patients may be at risk of developing thrombotic complicatio ns with additional heparin exposure.