Clotting Time Results Are Not Interchangeable Between EXTEM and FIBTEM on Rotational Thromboelastometry

Objective: To explore how cytochalasin D (CyD) affects clot initiation and to compare clotting times (CTs) of EXTEM and FIBTEM on rotational thromboelastometry in cardiac surgical patients undergoing cardiopulmonary bypass (CPB). Design: Retrospective cohort study with translational in vitro coagulation experiments. Setting: Single-center, tertiary, academic medical center. Participants: Patients who underwent cardiac surgery with CPB between November 2015 and August 2017. Intervention: None. Measurements and Main Results: The study\u27s primary measurements were CTEXTEM and CTFIBTEM before and after CPB. Additionally, the authors performed translational in vitro coagulation experiments using commercial plasma. In these experiments, the impact of CyD on in vitro thrombin generation (TG) was assessed using 10 platelet-rich plasma (PRP) samples and calibrated automated thrombogram. The impact of CyD on ROTEM-CT also was evaluated in vitro using the same 10 PRP samples. One hundred fifty-three patients had clinical CTEXTEM and CTFIBTEM measurements. CTFIBTEM was shorter than CTEXTEM before and after CPB by 6.8% (95% confidence interval [CI], 5.5-8.1) and 8.9% (95% CI, 4.7-13.0), respectively. These results correlated with in vitro experiments, where TG lag time was shortened by CyD and CTFIBTEM was shorter than CTEXTEM. Conclusion: CyD shortens the onset of TG and clot formation, resulting in shorter CTFIBTEM than CTEXTEM. The authors’ data suggest that CTEXTEM and CTFIBTEM are not interchangeable. Additional clinical studies are warranted to assess if CTFIBTEM can be used to optimize the indication for plasma transfusion