Failure of current strategies in the prevention of thrombosis in patients with heparin-induced thrombocytopenia: a clinician's perspective.

Heparin-induced thrombocytopenia (HIT), and heparin-induced thrombocytopenia with thrombosis syndrome (HITTS), are immune-mediated complications of heparin therapy associated with significant morbidity and mortality. Although much has been learned about the pathophysiology of this syndrome, there are many difficult issues remaining for physicians involved in the daily care of the patient about the diagnosis, prevention, and treatment. To determine whether the earliest detection of HIT and heparin cessation impacted outcome, 116 consecutive patients at a single institution, with HIT diagnosed by platelet aggregometry, were divided into groups by time to heparin cessation based on daily platelet counts. Thrombocytopenia was defined in two ways: as a 50% decline from baseline and an absolute platelet count of less than 100x10(9)/L. The overall thrombosis rate was 39% and was predominantly venous. The mortality rate of 27% was similar in patients with both HIT and HITTS. Despite heparin cessation at less than 48 h from the onset of thrombocytopenia (mean 0.5 days), there were no differences in thrombosis or mortality when compared to patients with later heparin cessation (mean 4.3 days). In summary, early detection of HIT with heparin cessation is insufficient therapy for the management and treatment of HITTS. An alternative to this strategy in the treatment of patients with HIT is indicated.