Heparin-induced inhibitory effects of a prothrombin complex concentrate on global tests of haemostasis

Correct dosing of Prothrombinex-VF in normalising elevated international normalised ratio in critically ill patients: a prospective cohort pilot study

BACKGROUND

Prothrombinex-VF is being increasingly used as an off-label therapy to correct non-warfarin-related elevations in international normalised ratio (INR) in the critically ill. Currently there are no dosing guidelines for such use.

AIMS

To validate a prediction equation, embedded in a smartphone application (app), to guide dosing of Prothrombinex-VF in critically ill patients.

METHODS

A prospective pilot cohort study of critically ill adult patients with elevated INRs who were treated with Prothrombinex-VF. The main outcome measured was INR following Prothrombinex-VF administration.

RESULTS

Of the 31 patients included, five (16%) were taking warfarin prior to admission and 14 (45%) had chronic liver disease. There was a significant decrease in INR after Prothrombinex-VF treatment (P < 0.001) and a significant correlation between the app's predicted INRs and the measured INRs (r = 0.63 and P < 0.001). The app's predicted INRs were less accurate for patients with chronic liver disease than for those without. Overall, the app's recommendations achieved an INR either similar to (29.6%) or better than (55.6%) what would have been achieved had the warfarin reversal guidelines been applied to dose the Prothrombinex-VF.

CONCLUSION

The app appeared to be reasonably accurate at predicting normalisation of elevated INRs after administration of Prothrombinex-VF, especially among patients without liver disease. Its dosing recommendations were similar to or possibly better than preexisting warfarin reversal guidelines in over 85% of the situations analysed, if we assume a higher dose of Prothrombinex-VF would achieve a greater reduction in INR than a lower dose.

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

INTRODUCTION

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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 parameters.

Management of Periprocedural and Early Pericardial Effusions With Tamponade Following Ablation of Atrial Fibrillation With Uninterrupted Factor Xa Inhibitors: A Case Series

INTRODUCTION

Because of the absence of a dedicated reversal agent, the outcome of pericardial effusion (PE) following procedures performed with uninterrupted apixaban or rivaroxaban is unknown. We report the characteristics of PEs presenting with tamponade in patients undergoing AF ablation with uninterrupted factor Xa inhibition (FXaI) to understand their management and prognosis.

METHODS AND RESULTS

We performed a multicenter cross-sectional survey in 10 centers across the United States. Patient data were obtained by chart review. In all patients the procedure was performed with uninterrupted FXaI. A total of 16 PEs requiring intervention were reported from 5 centers. Two patients were on apixaban 5 mg BD, the remaining on rivaroxaban 20 mg OD. Eleven PEs occurred in the periprocedural setting, and 5 PEs occurred from 1 to 28 days after the procedure. Pericardiocentesis and drainage were performed in all cases. Protamine and 4-factor prothrombin complex concentrate (4F-PCC) were given in all periprocedural cases. Two patients required surgery: in one case coagulation of the pericardial blood prevented effective drainage, and in the other bleeding was secondary to a steam pop-induced atrial tear. None of the postprocedural cases required FXaI reversal and the dose of rivaroxaban was temporarily reduced. No fatal outcomes or thromboembolic events were reported.

CONCLUSION

Pericardiocentesis and drainage with FXaI reversal proved effective in the management of acute PEs with tamponade occurring periprocedurally in patients undergoing AF ablation with uninterrupted FXaI. Early postprocedural effusions can be treated with pericardiocentesis without the need of a reversal agent.

Clotting factor product administration and same-day occurrence of thrombotic events, as recorded in a large healthcare database during 2008-2013

BACKGROUND

Thrombotic events (TEs) are serious adverse events that can occur following administration of clotting factors (CFs).

OBJECTIVES

To evaluate occurrence of same-day TEs for different CF products and potential risk factors.

METHODS

A retrospective cohort study of individuals exposed to CF products during 2008-2013 was conducted using a large commercial insurance database. CF products were identified by procedure codes, and TEs were ascertained via diagnosis codes. Crude same-day TE rates (per 1000 persons exposed) were estimated overall and by congenital factor deficiency (CFD) status, CF products, age and gender. Multivariable logistic regression analyses were used to control for confounding. Laboratory analysis was used to compare the procoagulant activities of FIX products.

RESULTS

Of 3801 individuals exposed to CFs, 117 (30.8 per 1000) had same-day TEs recorded. The crude same-day TE rate was higher for CF users without CFD, 70.2 (102 of 1452), as compared with those with CFD, 6.4 (15 of 2349) (RR, 11.0; 95% CI, 6.4-18.9). For individuals without CFD, a significantly increased same-day TE risk was identified for factor IX complex (OR, 6.92; 95% CI, 3.11-15.40), factor VIIa (OR, 9.42; 95% CI, 4.99-17.78) and other products when compared with fibrin sealant. An increased risk of a TE was found with older age (≥ 45 years), history of TEs and underlying health conditions. The laboratory identified elevated procoagulant activity in Profilnine(®) and Benefix(®) .

CONCLUSIONS

The study shows an increased same-day TE risk for CF users without CFD and suggests substantial off-label CF use. The study findings also show elevated same-day TE rates for different CF products and suggest the importance of product properties and patient factors.

Biochemical characterization of prothrombin complex concentrates in China

Despite increasing use of prothrombin complex concentrates (PCCs), there is little knowledge about the biochemical characterization of Chinese PCCs. Six Chinese PCCs were investigated and compared with PCCs (Octaplex®) from Europe. The levels of coagulation factors and inhibitors were detected. The presence of activated coagulation factors was assessed. Furthermore, their thrombin inhibitory capacities, specific activity and purity were assayed. All above parameters of biochemical properties were statistically analyzed. Chinese PCCs contained FⅡ, Ⅶ, Ⅸ and Ⅹ, protein C, S and Z, heparin and extremely low level antithrombin, as well as Octaplex®. The measured FⅨ activities were similar to those declared, however the measured potency of FⅡ, Ⅶ and Ⅹ greatly exceeded the labeled. Though all preparations were negative for activated coagulation factors in non-activated partial thromboplastin time test, the activated coagulation factor Ⅶ (FⅦa) remained in all PCCs and its content differed greatly. Overall, FⅦa content of Chinese PCCs was higher than that of Octaplex®. Further, Chinese PCCs were inferior to Octaplex® in the thrombin inhibitory capacities, specific activity and purity. In summary, compared with Octaplex®, Chinese PCCs' errors about the labeled activity of coagulation factors and probably high risks of thrombosis should be considered.

Thrombin generation capacity of prothrombin complex concentrate in an in vitro dilutional model

Background

The use of PCC for the treatment of trauma-induced coagulopathy potentially increase the risk of thromboembolism and disseminated intravascular coagulation, which is addressed to an imbalance of both pro- and anticoagulants. As PCCs differ in composition, we used an in vitro dilutional approach to assess the overall thrombin generation of five different PCCs through various laboratory assays.

Methods

The vitamin K-dependent coagulation factors, heparin, and antithrombin were assessed in five commercially available PCCs. The procoagulant potential of the PCCs was assessed in plasma and whole blood from 4 healthy donors by means of classical coagulation assays, thrombin generation assay and thromboelastometry. In order to reflect coagulopathy, whole blood was diluted to 80, 60, 40, and 20% with Ringer’s lactate solution.

Results

The five different PCCs were characterised by comparable levels of factors II, VII, IX and X (all around 20–30 IU/mL), whereas the heparin (0 to 17.6 IU/mL) and antithrombin (0.06 to 1.29 IU/mL) levels were remarkably different between manufactures. In vitro dilution of blood induced a prolongation of the PT and aPTT, and attenuation of thrombin generation and ExTem induced thromboelastometry. Overall, non- or low-heparin containing PCCs restored the in vitro dilutional coagulopathy, whereas PCCs containing heparin have an anticoagulant effect. The thrombin generation assay showed to be the most sensitive method for assessment of PCC effects.

Conclusions

This study shows that most available PCCs are not balanced regarding their pro- and anticoagulants. The effect of measured differences in thrombin generation among different PCCs requires further investigations to elaborate the clinical meaning of this finding in the treatment of trauma induced coagulopathy.

Heparin-induced effects of prothrombin complex concentrates in thromboelastometry

BACKGROUND

Prothrombin complex concentrates (PCC) are currently used to treat congenital or acquired coagulation factor deficiency. In case of serious bleeding caused by new oral anticoagulant agents, reversing treatment with PCC is under debate. PCC preparations mostly contain heparin to prevent thromboembolic events. In factor VIII and IX deficient plasma, Takeyama et al. observed in vitro a heparin effect at appropriate concentrations of PCCs. The aim of the present experiment was to investigate the heparin effect of four factor-PCC at clinically relevant concentrations in whole blood. In an in vitro experiment, we compared the PCC preparation used in the experiments of Takeyama with a high heparin content to a new heparin-free PCC preparation.

METHOD

After ethics committee approval and written informed consent, the citrated whole blood was obtained from ten healthy volunteers. We tested heparin-containing Prothromplex(®) and heparin-free Cofact(®) at concentrations of 0.31, 0.63, and 1.25 IU/ml. Protamine was added to another set of samples (1:1 heparin:protamine). We used the NATEM test in the rotational thromboelastometer ROTEM(®).

RESULTS

In the heparin PCC preparation, we observed a significant (p < 0.001) concentration-dependent prolongation in CT and CFT, even at the lowest concentration. MCF was also significantly reduced. The heparin effect was reversible by protamine. The heparin-free PCC did not affect the onset of coagulation. The interpretation of the alpha-angle showed no increased thrombus formation in heparin-free PCC preparation.

CONCLUSION

Our results extend the report of Takeyama et al. At clinically relevant PCC concentrations, the heparin effect was significant in thromboelastometry. The heparin content of PCCs should be considered in clinical routine.