Prothrombin Complex Concentrate, a General Antidote for Oral Anticoagulation

Prothrombin complex concentrate (PCC) is used for the rapid reversal of vitamin K antagonist (VKA) anticoagulation. PCC is also applicable in situations requiring rapid reversal of anticoagulation by non-vitamin K antagonist direct thrombin and factor Xa inhibitor oral anticoagulants (NOACs), thereby making PCC a general antidote for oral anticoagulation. In this chapter, the composition of different PCC brands is reviewed and a negative effect of heparin supplement in some products is recognized. Mode of action of anticoagulation reversal by PCC is explained. Dosage and clinical efficacy, two closely related issues, are discussed and based on reviewed data recommendations are given that may prohibit too low PCC dosing, especially in NOAC anticoagulation. Use of unsuitable laboratory assays has raised needless controversy as to the applicability of PCC to reverse anticoagulation by NOACs, in particular dabigatran. In this chapter, various laboratory assays are evaluated for their applicability in monitoring reversal of anticoagulation

Use of DOAC Stop for elimination of anticoagulants in the thrombin generation assay

Calibrated automated thrombography (CAT) is useful in monitoring the anticoagulant status of patients treated with direct oral anticoagulants (DOACs). This as well as other applications of the CAT are hampered by the wide inter-individual variation, making the diagnosis of the anticoagulant status of a patient on DOAC difficult when using normal pooled plasma as a reference. With dabigatran, the CAT is further hampered, as this direct thrombin inhibitor also inhibits the calibrator that is used in CAT. In this study we examined the added value of the universal DOAC adsorbent DOAC Stop in CAT. For this, we used normal pooled plasma spiked with apixaban, dabigatran, edoxaban or rivaroxaban, and performed CAT with 5 pM tissue factor. DOAC Stop effectively removed DOACs from plasma, leaving the DOAC Stop-treated plasma slightly more procoagulant compared to sham treated, non-anticoagulated plasma. Examining levels of natural coagulation inhibitors revealed a slight reduction in tissue factor pathway inhibitor upon DOAC Stop treatment. When DOAC Stop-treated plasma was used in the calibrator wells, normal unaffected calibration curves were observed, even when dabigatran was present. In conclusion, DOAC Stop can be used to abolish dabigatran influences of anticoagulated plasma when used in the calibrator wells. Also, the anticoagulant status of a DOAC treated patient can be diagnosed simply by comparing untreated plasma with the same plasma sample treated with DOAC Stop. Using this approach, a minor DOAC-independent increase in CAT response in the DOAC Stop-treated sample should be taken into account

Heparin supplement counteracts the prohemostatic effect of prothrombin complex concentrate and factor IX concentrate: An in vitro evaluation

Coagulation factor concentrates like factor IX (FIX) and prothrombin complex concentrate (PCC) can contain anticoagulant substances that may hamper their procoagulant effectiveness in the treatment of hemophilia B or reversal of oral anticoagulation, as well as the laboratory assessment thereof. The aim of the present study was to evaluate the influence of anticoagulant heparin supplement on the prohemostatic potential of different PCCs and FIX concentrates. Prohemostatic potential was evaluated in vitro employing PT/aPTT, thrombography (TGA) and thromboelastography (TEG) with FIX deficient plasma, vitamin K antagonist (VKA)-anticoagulated plasma and plasma anticoagulated with rivaroxaban. Most PCCs contained heparin, while heparin was detected in 1 out of 4 examined FIX concentrates. All heparin-containing clotting factor concentrates showed severely hampered prohemostatic effects when therapeutic doses were added to anticoagulated plasmas. Upon heparin removal, comparable prohemostatic effects were observed. Of importance is the notion that the anticoagulant effect of heparin was enhanced by rivaroxaban, resulting in a 7 fold increased PT sensitivity towards heparin in the presence of 500μg/L rivaroxaban. Compositional differences between clotting factor concentrates should be taken into account. Therapeutic levels of heparin may be co-infused when treating emergency bleeds with high prohemostatic drug doses, particularly those recommended in the reversal of non-VKA anticoagulants such as rivaroxaban by PCC. Given the relative short half-life of heparin compared to vitamin K-dependent clotting factors, an anticoagulant heparin effect shortly after concentrate infusion should be considered clinically and while interpreting laboratory coagulation parameter

Platelets compensate for poor thrombin generation in type 3 von Willebrand disease

In type 3 von Willebrand disease (VWD3), the most severe form with absent von Willebrand factor (VWF), the bleeding phenotype is variable. Platelet contribution to the hemostatic defect in VWD3 calls upon further studies. We investigated the contribution of platelets to in vitro thrombin generation (TG) and platelet procoagulant activity in VWD3. TG was assessed by calibrated automated thrombogram (CAT) in platelet-poor (PPP) and –rich plasma (PRP) from 9 patients before and in 6 patients also 30 min after receiving their regular VWF therapy. Responsiveness of PPP to FVIII and protein S was also investigated. TG data were compared with routine laboratory variables, rotational thromboelastometry (ROTEM) and platelet expression of P-selectin and phosphatidylserine in flow cytometry. Compared with healthy controls, TG was markedly decreased in VWD3 PPP (peak thrombin was 16% of normal median), but not in PRP (77% of normal median) (p = 0.002). Six out of nine patients (67%) were high responders in their platelet P-selectin, and 5/9 (56%) in phosphatidylserine expression. Replacement therapy improved TG in PPP, while in PRP TG only modestly increased or was unaffected. In PPP, FVIII levels associated with TG and in vitro FVIII-supplemented TG inclined up to threefold. Conversely, a FVIII inhibitory antibody reduced plasma TG in all, but especially in patients with remnant FVIII levels. Inhibition of protein S improved plasma TG, particularly at low FVIII levels. ROTEM failed to detect VWD3. In VWD3, TG is reduced in PPP and regulated by FVIII and protein S, but TG is close to normal in PRP. VWD3 platelets seem to compensate for the FVIII-associated reduction in TG by their exposure of P-selectin and phosphatidylserine

Von Willebrand factor targets IL-8 to Weibel-Palade bodies in an endothelial cell line

Vascular endothelial cells are able to store the chemotactic cytokine interleukin-8 (IL-8) in specialized storage vesicles, Weibel-Palade bodies, together with von Willebrand factor (VWF) and P-selectin. We investigated whether VWF plays a role in the sorting of IL-8 into these organelles. We examined the effect of VWF expression on IL-8 targeting in an endothelial cell line (EC-RF24). This cell line has retained the typical phenotypic characteristics of primary endothelial cells but has lost the capacity to produce VWF in appreciable amounts. EC-RF24 cells were retrovirally transduced with a vector encoding a VWF-green fluorescent protein chimera (VWF-GFP). This approach enables direct visualization of the cellular distribution and secretory behavior of the VWF-GFP hybrid. Expression of VWF-GFP resulted in the generation of Weibel-Palade body-like organelles as shown by the colocalization of VWF-GFP and P-selectin. VWF-GFP expressing EC-RF24 cells also showed significant colocalization of VWF-GFP with IL-8 in these storage vesicles. Live cell imaging revealed that the number of VWF-GFP-containing granules decreased upon cell stimulation. These observations indicate that VWF plays an active role in sequestering IL-8 into Weibel-Palade bodie