Abstract - Text

Offenlegung Interessenkonflikt:

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Methods

Data were collected from surgical ICU patients  (n=257) and patients with cardiac assist devices (n=83) with suspected HIT. Inclusion criteria were thrombocytopenia and or thrombosis and or an intermediate to high pretest probability of HIT (4T score ≥ 4).

Results

55/257 (21%) ICU patients with without assist devices and 27/83 (33%) patients with ECC had IgG antibodies against PF4/heparin complexes. 10/55 (18.18%) EIA positive patients with surgery had platelet activating antibodies. In contrast, sera from 6/27 EIA positive patients with ECC tested positive in the HIPA test. 3/27 sera showed heparin-dependent and 4/27 (14.8%) sera showed heparin-independent platelet activation. While prevalence of HIT in patients with suspected HIT seems to be similar between patients with and without ECC (3.5% vs. 3.6%), higher number of patients with HIT antibodies and heparin-independent platelet activation was observed in patients with ECC compared to surgical ICU patients (4.8% vs. 0.38%, respectively).

Background

Heparin-induced thrombocytopenia (HIT) is a serious drug induced reaction with potential life threatening complications. Since thrombocytopenia and thrombosis are common findings in ICU patients undergoing extracorporeal circulation (ECC) it is a diagnostic challenge to confirm or rule out HIT based on the results of immunoassays and functional assays. But sometimes platelet activation in vitro also due to false positive functional assays.

Conclusion

Our study demonstrates the challenges in the current diagnostic approach for HIT in ICU with surgery and ECC. The higher incidence of thrombocytopenia and IgG immunization against PF4/heparin complexes in this population impairs the performance of a standardized diagnostic algorithm that uses the 4Ts-score and a rapid immunoassay. New developments of functional assays are needed to improve diagnostic approaches.