engleski

Relationship Between Dabigtran Concentrations in Plasma and Results of Routine Coagulation Assays PT, APTT, TT and Fibrinogen

Background: Routine coagulation tests prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen are affected by dabigatran therapy, but are not standardized for assessment of its anticoagulant effect. However, exact knowledge of its impact on routine coagulation tests is a precondition for their correct interpretation. Aims: To assess relationship between dabigatran concentrations and results of routine coagulation assays. Methods: The study included 43 patients on dabigatran therapy. Plasma dabigatran concentrations were determined with DTI Innovance assay (Siemens, Germany) as a part of Croatian Science Foundation project HRZZ-IP- 2016-06-8208. All coagulation assays were determined on BCSXP analyzer using commercial reagents (Table 1). Results: Dabigatran plasma concentrations ranged from 22 to 401 ng/mL (median 101 ng/mL ; 95%CI 59-157 ng/mL). TT was unmeasurable (>150 s) in all patients with dabigatran levels above 100 ng/ml with significantly higher (P<0.0001) dabigatran levels compared to patients with TT<150s (median 69s). Among all patients, 16/43=0.37 had PT and 5/43=0.12 had APTT results in the reference range while 27/43=0.63 and 38/43=0.88 had prolonged PT and APTT, respectively. PT, APTT and fibrinogen were significantly different between patients with dabigatran levels below and above 100 ng/mL (Table 1). Conclusions: The results of routine coagulation tests are strongly dependent on dabigatran plasma concentrations. Due to its high sensitivity, TT could be useful for detecting minimal dabigatran levels in plasma, but is too sensitive for dabigatran levels above 100 ng/mL. PT lacks sensitivity in detecting therapeutic levels of dabigatran but neither the APTT was invariably prolonged in patients with dabigatran levels below 100 ng/mL. In summary, routine coagulation tests PT, APTT and TT, although dependent on dabigatran concentrations, could not be used to assess therapeutic response to dabigatran therapy through a wide range of its concentrations in plasma.

Dabigratan, PT, aPTT, TT

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