Heparin induced thrombocytopenia after lower extremity arterial surgical procedures

Abstract

Objective. Heparin-induced anti-platelet antibodies are believed to be triggered by heparin administration. Little is known regarding the prevalence of these antibodies in specific surgical populations. The purpose of this study is to determine the prevalence of heparin-induced anti-platelet antibodies and whether this correlates with the development of thrombocytopenia (<100,000/μl) in patients undergoing lower extremity arterial surgery. Methods. Consecutive patients undergoing infra-inguinal lower extremity vascular surgical procedures were enrolled. Blood samples were prospectively obtained for measurement of platelet counts and heparin-induced antiplatelet antibodies by ELISA (HIPA Asserachrome, Diagnostica Stago) with a positive ELISA defined as an absorbance of greater than 28% of positive control. In positive plasma samples, ELISA was repeated for confirmation. The plasma samples were obtained preoperatively, at 7, 14, and 28 days postoperatively. At each time point, the mean platelet count of antibody seropositive patients was statistically compared to the mean platelet count of seronegative patients using a generalized linear model. Results. Thirty-five patients were enrolled; 24 were men (69%), with a mean age of 65.7 years (37–83). All patients underwent lower extremity arterial reconstructions or revisions of previous operations. At all time points, no significant differences were found between the mean platelet counts for patients positive for heparin-induced antiplatelet antibodies and the mean platelet counts of patients negative for the antibody. The percentage of patients that were antibody seropositive preoperatively, at 7, 14, and 28 days, was 9, 27, 43, and 37%, respectively. Conclusion. In patients undergoing lower extremity vascular surgical procedures, heparin-induced antibody seropositivity is present in a small percentage of patients preoperatively. Following heparin exposure, seropositivity increases to a peak of 43% at postoperative day 14, with 37% remaining seropositive at day 28. No patient developed thrombocytopenia. Whether this demonstrated that seropositivity in the postoperative period adversely affects graft outcome, particularly in patients receiving postoperative heparin, requires further study.