Heparin-induced thrombocytopenia

Abstract

Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin with significant morbidity and mortality. In this study, a retrospective review of all patients referred to the platelet study lab at East Carolina University who tested positive for heparin-induced platelet aggregation was performed. From May 1988 through March 1991, 40 patients with clinically suspected HIT were referred for platelet aggregation studies. Ten patients tested positive for in-vitro platelet aggregation in the presence of heparin. The clinical characteristics of these patients are reviewed. Results show a preponderance of surgical patients with 8/10 patients having undergone a primary major surgical procedure. Six of the eight surgical patients underwent a major vascular or cardiac procedure. The mortality rate for patients with heparin-induced in-vitro platelet aggregation was 30 per cent. Major thromboembolic morbidity was substantial (80%) with 5/10 patients requiring an extremity amputation. The estimated incidence of HIT in surgical patients in this series was 0.3 per cent. HIT is an unusual complication of heparin therapy with devastating morbidity and mortality. Patients undergoing a major vascular or cardiac procedure appear to be at increased risk. Increased awareness of the syndrome and careful monitoring of platelet counts in patients at high risk may reduce the morbidity and mortality.