Optimizing warfarin reversal--an ex vivo study

Prothrombin Complex Concentrates for Coagulopathy in Liver Disease: Single-Center, Clinical Experience in 105 Patients

Patients with liver disease frequently develop coagulopathy, and fresh frozen plasma is traditionally used for correction of coagulopathy to manage and prevent bleeding. Prothrombin complex concentrates (PCCs) offer an attractive alternative because they are more readily available and avoid large-volume transfusion. This retrospective, single-center study reviewed clinical use of PCC in patients with acute/chronic liver disease. A total of 105 patients with 194 episodes of PCC administration were reviewed. Data pertaining to indication, dosing, effectiveness, and safety were collected. The effect of PCC on coagulation was analyzed in patients for whom coagulation results were available 7 hours before and after PCC. Data on thromboembolic events and mortality within 4 weeks of PCC administration were captured. Most patients (77%) had chronic liver disease; the remainder had acute liver failure. Indications for PCC were preprocedure prophylaxis and treatment for active/recent bleeding in 48% and 52% of 194 treatment episodes, respectively. The median dose of PCC administered was 22 IU/kg (interquartile range, 16-29 IU/kg). Before PCC administration, 45% of patients had an international normalized ratio (INR) greater than 2.0, and 36% had fibrinogen levels of at least 1.5 g/L. PCC produced statistically significant reductions in prothrombin time and INR (coadministration with fibrinogen or cryoprecipitate: 3.1 versus 1.9; P < 0.001; no coadministration: 2.3 versus 1.8; P < 0.001). Three patients with multiple risk factors developed thrombotic events (hepatic artery thrombosis, incidental bilateral pulmonary embolism, nonocclusive portal vein thrombosis); there were no cardiovascular or cerebrovascular adverse events. Overall, 46 patients died of causes unrelated to PCC treatment. Conclusion: In patients with liver disease, PCC therapy was effective in improving coagulation test results without an excess of thrombotic events. Further assessment of PCC as hemostatic therapy in this setting is required.

A comparative study of prothrombin complex concentrates and freshfrozen plasma for warfarin reversal under static and flow conditions

Prothrombin complex concentrates (PCCs) and fresh-frozen plasma (FFP) have been clinically used for acute warfarin reversal. The recovery of prothrombin time (PT) or international normalised ratio (INR) is often reported as an endpoint, but haemostatic efficacies of PCCs and FFP may not be fully reflected in static clotting test in platelet-poor plasma. Using various in vitro assays, we compared the effects of two PCC preparations (3-factor PCC; Bebulin and 4-factor PCC; Beriplex) and FFP on warfarin reversal under static and flow conditions. First, we added an aliquot of either PCC (0.3 or 0.72 U/ml) or 20% FFP (v/v) to commercial warfarin plasma (INR 3.2, or 10.3), and then measured PT, factor II, factor VII, and thrombin generation. Subsequently, we collected whole blood samples from six consented warfarin-treated patients with mean INR 3.0 ± 0.5 (range 2.5–3.7), and compared clot formation under flow conditions at 280 s-1 before and after addition of either PCC preparation (0.3 and 0.6 U/ml) or 20% of FFP (v/v). PT/INR were restored by either PCC in plasma with INR 3.0, but they were more effectively corrected by 4-factor PCC than 3-factor PCC in plasma with INR 10.3. Effects of FFP were similar to 0.3U/ml of PCCs in terms of PT, but FFP was less efficacious than PCCs in recovering thrombin generation or factor II levels. In flow experiments, the onset of thrombus formation was shortened by either PCC, but not by FFP, contrary to shortened PT values. For warfarin reversal 20% volume replacement with FFP is inferior to PCCs.

Evaluation of Warfarin Reversal with 4-Factor Prothrombin Complex Concentrate Compared to 3-Factor Prothrombin Complex Concentrate at a Tertiary Academic Medical Center

BACKGROUND

The U.S. Food and Drug Administration recently approved a four-factor prothrombin complex concentrate (4-PCC) for warfarin reversal. The literature supporting its use over three-factor prothrombin complex concentrate (3-PCC) is limited.

OBJECTIVE

Our objective was to retrospectively compare the efficacy of 3-PCC to 4-PCC in reversing warfarin in patients who were actively bleeding.

METHODS

We conducted a single-center, retrospective cohort analysis of adult patients who received 3-PCC or 4-PCC for international normalized ratio (INR) reversal. Our study excluded patients not actively bleeding and not on warfarin. The main outcome was the percentage of patients who achieved warfarin reversal defined as INR ≤ 1.3 at first INR check post factor administration. We recorded baseline data including PCC dose, location of bleed, pre- and posttreatment INR, and time to INR reversal.

RESULTS

We included a total of 53 patients. Intracranial hemorrhage was the most common site of bleeding (26 [74.3%] in 3-PCC vs. 12 [66.7%] in 4-PCC). The mean dose of 3-PCC was 25.5 units/kg, compared to 27.9 units/kg of 4-PCC. The mean baseline INR was 2.3 in the 3-PCC group and 3 in the 4-PCC group (p = 0.03), and the first posttreatment INRs were 1.4 and 1.2, respectively (p < 0.01). Warfarin reversal was achieved in 15 (42.9%) patients who received 3-PCC and 15 (83.3%) patients who received 4-PCC (p < 0.01). Faster time to INR reversal was noted in the 4-PCC group vs. the 3-PCC group (3.7 vs. 5 h, p = 0.48).

CONCLUSION

A higher percentage of patients achieved warfarin reversal with 4-PCC compared to 3-PCC treatment. A prospective randomized control trial is necessary to confirm our results.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60-72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.

Efficacy of the prothrombin complex concentrate prothromplex in patients requiring urgent reversal of vitamin K antagonists or presenting with uncontrolled bleeding: a retrospective, single center study

The objective of the present study was to investigate the efficacy of a four-factor prothrombin complex concentrate (Prothromplex, PTX) in shortening prolonged international normalized ratio or controlling life-threatening bleeding. The study was a retrospective single-centre study that included 142 patients treated with PTX and allocated in three groups: patients on vitamin K antagonists (VKA) (acenocumarol) and undergoing invasive procedure or presenting with severe bleeding (n = 76), patients treated with VKA presenting with intracranial haemorrhage (n = 22), and patients not on VKA and presenting with uncontrolled bleeding (n = 44). The primary outcome variable was international normalized ratio (INR) return to the norm after PTX infusion. Secondary outcome variables included bleeding control and reduction of transfusion rate. Overall, patients received a median of 1200 IU (≈15 IU/kg) of PTX, and INR decreased from 4 ± 3 to 1.7 ± 1.2 (P < 0.01) in all groups, although it remained at least 1.4 in 38% of patients (29.3% among patients receiving 25 IU/kg vs. 42.6% among those receiving 15 IU/kg; P < 0.05). Patients with initial INR at least 4 benefited the most from treatment. After PTX administration, there was a significant reduction in both transfused blood components units (P < 0.01) and estimated blood loss volume (from 1500 ± 1500 to 200 ± 100 ml; P < 0.01), and only one episode of deep venous thrombosis was observed. Administration of fixed doses of PTX shortened prolonged international normalized ratio and improved life-threatening bleeding in patients with or without VKA therapy. Higher dose attained a more adequate post-infusion INR.

The epidemic of pre-injury oral antiplatelet and anticoagulant use

BACKGROUND

As the population ages, an increasing number of trauma patients are taking antiplatelet and anticoagulant medications (ACAP) prior to their injuries. These medications increase their risk of hemorrhagic complications, particularly intracerebral hemorrhage. Clopidogrel and warfarin are common and their mechanisms well understood, but optimal reversal methods continue to evolve. The novel direct thrombin and factor Xa inhibitors are less well described and do not have existing antidotes.

METHODS

This article reviews the relevant literature on traumatic outcomes with use of ACAP medications, as well as data on ideal reversal strategies. Suggested algorithms are introduced, and future research directions discussed.

RESULTS

Although they are beneficial in preventing clot formation, once bleeding occurs ACAP medications contribute to increased morbidity and mortality, particularly in geriatric patient populations. The efficacy of clopidogrel reversal with platelet transfusions and DDAVP remains unclear. Warfarin use is best treated with the algorithm-driven use of plasma, vitamin K, prothrombin complex concentrates (PCCs) and possibly recombinant factor VIIa depending upon specific patient and injury factors. Optimal treatment for direct thrombin and factor Xa inhibitors has yet to be developed, but PCCs are promising for rivaroxaban and apixaban while dabigatran is best treated with medication cessation and the possible addition of activated PCCs or hemodialysis.

CONCLUSION

New developments in reversal of the ACAP medications are promising, particularly PCCs for warfarin and the factor Xa inhibitors. Function assays and clear antidotes are needed for the thrombin and Xa inhibitors. Research on outcomes and appropriate treatments is actively ongoing.

Guideline-concordant administration of prothrombin complex concentrate and vitamin K is associated with decreased mortality in patients with severe bleeding under vitamin K antagonist treatment (EPAHK study)

Introduction

In vitamin K antagonist (VKA)-treated patients with severe hemorrhage, guidelines recommend prompt VKA reversal with prothrombin complex concentrate (PCC) and vitamin K. The aim of this observational cohort study was to evaluate the impact of guideline concordant administration of PCC and vitamin K on seven-day mortality.

Methods

Data from consecutive patients treated with PCC were prospectively collected in 44 emergency departments. Type of hemorrhage, coagulation parameters, type of treatment and seven-day mortality mortality were recorded. Guideline-concordant administration of PCC and vitamin K (GC-PCC-K) were defined by at least 20 IU/kg factor IX equivalent PCC and at least 5 mg of vitamin K performed within a predefined time frame of eight hours after admission. Multivariate analysis was used to assess the effect of appropriate reversal on seven-day mortality in all patients and in those with intracranial hemorrhage (ICH).

Results

Data from 822 VKA-treated patients with severe hemorrhage were collected over 14 months. Bleeding was gastrointestinal (32%), intracranial (32%), muscular (13%), and “other” (23%). In the whole cohort, seven-day mortality was 13% and 33% in patients with ICH. GC-PCC-K was performed in 38% of all patients and 44% of ICH patients. Multivariate analysis showed a two-fold decrease in seven-day mortality in patients with GC-PCC-K (odds ratio (OR) = 2.15 (1.20 to 3.88); P = 0.011); this mortality reduction was also observed when only ICH was considered (OR = 3.23 (1.53 to 6.79); P = 0.002).

Conclusions

Guideline-concordant VKA reversal with PCC and vitamin K within eight hours after admission was associated with a significant decrease in seven-day mortality.

Rapid reversal of warfarin-associated hemorrhage in the emergency department by prothrombin complex concentrates

Life-threatening warfarin-associated hemorrhage is common, with a high mortality. In the United States, the most commonly used therapies--fresh frozen plasma and vitamin K--are slow and unpredictable and can result in volume overload. Outside of the United States, prothrombin complex concentrates are often used instead; these pooled plasma products reverse warfarin anticoagulation in minutes rather than hours. This article reviews the literature relating to warfarin reversal with fresh frozen plasma, prothrombin complex concentrates, and recombinant factor VIIa and provides elements for a management protocol based on this literature.

Bleeding risk in warfarinized patients with a therapeutic international normalized ratio: the effect of low factor IX levels

OBJECTIVE

Bleeding is the main complication of warfarin therapy, even patients with an international normalized ratio (INR) in the target range can suffer bleeding, suggesting that INR does not perfectly reflect the therapeutic effect of warfarin. We hypothesized the INR might underestimate the level of anticoagulation in a subject with a lower factor (F) IX level than average.

METHODS AND RESULTS

We modeled warfarin anticoagulation in our in vitro thrombin generation (TG) model by adjusting the levels of vitamin K-dependent factors to those of patients with an INR of 2-3. Variation in FIX had a marked effect on TG but had no effect on the prothrombin time (PT)-INR. A prospective observational, cross-sectional clinical study including 341 consecutive patients admitted to the emergency department with an INR between 2 and 3, showed a statistically lower FIX activity in bleeders (P = 0.004) compared with others. No correlation was found between TG capacity and PT-INR results (P = 0.36). However, in patients, presenting with a warfarin-related hemorrhage, TG was significantly lower (P < 0.001) than others. A correlation on the boundary of significance was observed between TG capacity and FIX levels (P = 0.09).

CONCLUSION

These data demonstrates that patients who bleed when their PT-INR is in the target range 2-3 might have defective TG related to a lower level of FIX than expected.

Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects

Vitamin K is required for the carboxylation of Gla-proteins in the liver (coagulation factors) and extra-hepatic tissues, such as bone (osteocalcin, OC), and arterial wall (matrix Gla-protein, MGP). Although the coagulation factors are essentially fully carboxylated under normal conditions, 10–40 % of OC and MGP remains undercarboxylated. We were therefore interested to study the dose–response effects of extra intake of menaquinones on the carboxylation of the extra-hepatic Gla-proteins. A total of forty-two healthy Dutch men and women aged between 18 and 45 years were randomised into seven groups to receive: placebo capsules or menaquinone-7 (MK-7) capsules at a daily dose of 10, 20, 45, 90, 180 or 360 μg. Circulating uncarboxylated OC (ucOC), carboxylated OC (cOC) and desphospho-uncarboxylated MGP were measured by ELISA. The ucOC:cOC ratio was calculated from circulating ucOC and cOC values. Endogenous thrombin potential and peak height were determined by calibrated automated thrombography. To increase the statistical power, we collapsed the treatment groups into three dosage groups: placebo, low-dose supplementation (doses below RDA, Commission Directive 2008/100/EC), and high-dose supplementation (doses around RDA, Commission Directive 2008/100/EC). MK-7 supplementation at doses in the order of the RDA (Commission Directive 2008/100/EC) increased the carboxylation of circulating OC and MGP. No adverse effects on thrombin generation were observed. Extra MK-7 intake at nutritional doses around the RDA (Commission Directive 2008/100/EC) improved the carboxylation of the extra-hepatic vitamin K-dependent proteins. Whether this improvement contributes to public health, i.e. increasing the protection against age-related diseases needs further investigation in specifically designed intervention trials.

Treatment of warfarin-related intracranial hemorrhage: a comparison of prothrombin complex concentrate and recombinant activated factor VII

OBJECTIVE

Warfarin-related intracranial hemorrhage (ICH) is a devastating complication of warfarin therapy. Several studies have demonstrated successful correction of the international normalized ratio (INR) using prothrombin complex concentrate (PCC) or recombinant activated factor VII (rFVIIa). To our knowledge, no study has directly compared these agents for treatment of warfarin-related ICH.

METHODS

We retrospectively reviewed the charts of 15 patients who received rFVIIa and 9 who received PCC for treatment of warfarin-related ICH over a 2-year period. The primary objective was to compare the efficacy of rFVIIa and PCC in correcting the INR to 1.3 or less. Baseline INR was compared to INR obtained within 1, 3, 6, 12, and 24 hours after rFVIIa or PCC administration.

RESULTS

Six patients in the rFVIIa group and five in the PCC group had a follow-up INR within 1 hour of agent administration. In the rFVIIa group, the mean INR decreased from 6.1 to 1.1 and from 2.3 to 1.48 in the PCC group. At 6 hours, all rFVIIa patients and six (67%) PCC patients had at least one subsequent INR, with 93% and 50% correcting to an INR of 1.3 or less. Mean dose for all patients included was 53.4 ± 17.5 μg/kg and 27.8 ± 15.4 units/kg for rFVIIa and PCC, respectively.

CONCLUSION

Correction of the INR is more reliably obtained with rFVIIa when compared to PCC. Larger, prospective studies comparing these therapies for warfarin-related ICH are needed.