[Hypercoagulation caused by heparin-associated type II thrombocytopenia]

Abstract

The immunological type of heparin-associated thrombocytopenia (HAT II) is a severe complication of heparin treatment and is associated with arterial and venous thrombosis. Only patients with absolute thrombocytopenia have prompted suspicion of HAT in clinical practice. We report on a 44-year-old male who developed thromboembolic episodes after coronary angiography such as reinfarction and thrombotic episodes of A. brachialis. Fibrinolytic therapy combined with i.v. unfractionated heparin treatment was the therapy of choice and was followed by severe further thromboembolic adverse effects. Besides an impaired fibrinolytic response and elevated antiphospholipid antibodies, we diagnosed HAT type II in HIPA and ELISA (Stago. Boehringer-Mannheim). This special patient had platelet counts within a normal range, when developing the thromboembolic episodes. It appears that the normal platelet count during the thromboembolic episodes reflect a relative thrombocytopenia. From a clinical point of view we recommend the use of a lab panel to exclude HAT type II in patients with thromboembolic episodes under therapy with fractionated or unfractionated heparin. Platelet counts within a normal range are not absolute exclusion criterion for HAT II.