Thrombin generation as a predictor of outcomes in patients with non-traumatic intracerebral hemorrhage

Background

Non-traumatic intracerebral hemorrhage (ICH) accounts for 10–15% of all strokes and leads to a higher rate of mortality as compared to ischemic strokes. We aimed to find out whether the thrombin generation assay (TGA) could predict outcomes in patients with ICH.

Patients and methods

In this prospective, observational study, 87 consecutive patients with ICH and 164 healthy controls were included. Computed tomography (CT), detailed clinical investigation, and laboratory investigations were performed from patients on admission. TGA was performed using stored platelet poor plasma obtained on admission. Lag time, endogen thrombin potential (ETP), peak thrombin, and time to peak parameters were calculated. Short- and long-term outcomes of ICH were defined at 14 days and 3 months post-event according to the NIHSS and the modified Rankin Scale (mRS), respectively.

Results

Peak thrombin was significantly higher in patients as compared to controls (397.2 ± 93.9 vs. 306 ± 85.3 nM, p < 0.0001). Lag time, ETP, and time to peak parameters showed a significant positive correlation with CRP in both groups. In patients with worse long-term functional outcomes, peak thrombin was significantly higher as compared to those with favorable outcomes [mRS 2–6 median: 402.5 (IQR:344.8–473.8) vs. mRS 0–1: 326.4 (294.2–416.1) nM, p = 0.0096]. Based on the statistically optimal threshold of 339.1 nM peak thrombin, the sensitivity and specificity of this parameter to determine mRS 2–6 as an outcome were 80.8 and 64.7%, respectively. In a binary logistic regression model including age, sex, BMI, smoking status, NIHSS on admission, D-dimer, and peak thrombin (>339.1 nM), only NIHSS and the peak thrombin parameters remained in the model as significant, independent predictors of poor outcome. Lag time and time to peak showed a modest, significant negative correlation with intracerebral bleeding volume on admission (r = −0.2603, p = 0.0231 and r = −0.3698, p = 0.0010, respectively). During the follow-up of patients, estimated hemorrhage volumes on day 90 showed significant positive association with the ETP and peak thrombin parameters (r = 0.3838, p = 0.0363 and r = 0.5383, p = 0.0021, respectively).

Conclusion

In patients with ICH, TG was increased as compared to healthy controls, which might be explained by the presence of higher inflammatory parameters in patients. Peak thrombin measured on admission might be a useful tool to predict outcomes in patients with ICH.

Pharmacodynamic monitoring of factor VIII replacement therapy in hemophilia A: Combining thrombin and plasmin generation

BACKGROUND

Clinical severity of hemophilia A (HA) varies, possibly due to interplay of many factors in the hemostatic pathway. Pharmacokinetic monitoring of factor VIII (FVIII) replacement therapy in HA patients consists of measuring FVIII activity levels and subsequent dose adjustment. The Nijmegen Hemostasis Assay (NHA) measures thrombin generation (TG) and plasmin generation (PG).

OBJECTIVE

To determine differences in TG and PG between HA patients before and during a pharmacokinetic study and identify best parameters to develop a pharmacodynamic model.

METHODS

Twenty-five HA patients (baseline FVIII < 1-9 IU/dL) underwent a pharmacokinetic study with a single dose of 25-50 IU/kg standard half-life FVIII concentrate. At baseline and after administration of FVIII TG and PG parameters were measured with the NHA.

RESULTS

FVIII activity level increased from median 1.0 IU/dL (interquartile range < 1.0-6.0) to 71 IU/dL (62-82) 15 minutes after administration and decreased to 15 IU/dL (10-26) at 24 hours. TG was enhanced simultaneously, with thrombin peak height (TPH) increasing from 22nM (15-35) to 222nM (159-255), and thrombin potential (TP) from 404nM/min (undetectable-876) to 1834nM/min (1546-2353). Twenty-four hours after infusion, TG parameters remained high (TPH 73nM [58.5-126.3]; TP 1394nM/min [1066-1677]) compared to FVIII activity level. PG showed hyperfibrinolysis in severe HA patients compared to mild patients and controls, which normalized after FVIII supplementation.

CONCLUSION

HA patients showed clear differences in baseline TG and PG despite having comparable FVIII activity levels. These results reveal a discrepancy between FVIII activity level and TG, in which the latter may be a better parameter to monitor individualized treatment in HA patients.

Thromboelastography in pre-surgery monitoring in Hemophilia A with high inhibitor titer: case report and literature review

The development of factor VIII inhibitors (allo-antibodies) continues to be a major complication in the management of severe forms of hemophilia A, especially as far as treatment and treatment response monitoring is concerned. The need to implement a reliable laboratory assay is all the more obvious if major surgery occurs, when conventional tests (activated partial thromboplastin time APTT, prothrombin time PT, factor VIII level) are of no avail and there is a very fragile balance between bleeding and thrombosis.

We report the case of a 32 year-old patient diagnosed with severe Hemophilia A, referred to the Comprehensive Center for the Diagnosis and Treatment of Hemophilia of the Fundeni Clinical Institute for a multidisciplinary assessment in view of a total left hip arthroplasty due to aseptic necrosis of the femoral neck.

Workup showed a high inhibitor titer (>200 BU). Taking into consideration the interindividual variability of the response to bypassing agents, as well as the bleeding risk associated with a major orthopedic surgery, we used thromboelastography (TEG) to assess the patient’s response to aPCC (activated prothrombin complex concentrate) and rFVIIa (activated recombinant factor VII). The findings helped select the optimal replacement scheme to ensure perioperative hemostasis.

Kaolin, used to trigger coagulation in thrombin generation test, increases sensitivity of the method in hemophilia patients

: Thrombin generation test (TGT) is well established tool to research blood coagulation in plasma of hemophilia patients. Traditionally coagulation in this test is triggered by a tissue factor (TF), an extrinsic coagulation pathway activator. However, it is known that disorders of the intrinsic pathway are most important for coagulation in hemophilia. In this study, we hypothesized that triggering coagulation via the intrinsic pathway could increase a sensitivity of the TGT to monitor hemophilia treatment. The aim of this study was to compare thrombin generation in hemophilia A patients with inhibitors to factor VIII before and after infusion of bypassing agent [recombinant-activated factor VIIa (rVIIa)] using standard activation of coagulation by TF or by kaolin, an activator of coagulation by intrinsic pathway. Endogenous thrombin potential (ETP) in nine patients was measured. ETP before (ETP0) and 60 min after rVIIa infusion (ETP60) were compared. It was shown that ETP0 and ETP60 were significantly different when using any coagulation activator (paired Student's t test, P = 0.017 and 3.7 × 10 for clotting activation by TF and kaolin, respectively). The ratios of ETP60/ETP0 were 1.2 ± 0.2 or 30.0 ± 22.4 (mean ± SD, n = 9) for coagulation activated by TF or kaolin, respectively, and were significantly different (paired Student's t test, P < 0.005). The TGT clearly distinguished between ETP0 and ETP60 in the case of any coagulation activator, but ETP increasing after rVIIa infusion was significantly higher when activated with kaolin. This provided increased sensitivity of this method for monitoring hemophilia therapy.

Limited factor VIIa surface localization requirement of the factor VIIa-induced overall thrombin generation in platelet-rich hemophilia A plasma

BACKGROUND

Thrombin generation assay (TGA) and thrombelastography (TEG) are increasingly employed, global, in vitro methods for assessment of the procoagulant potential of plasma/blood and possibly ideally suited tools to monitor, for example, therapy with recombinant factor VIIa (FVIIa). It remains controversial to what extent results obtained with spiked and postinfusion samples reflect the outcome in patients.

OBJECTIVE

To characterize the TGA response to FVIIa in hemophilic plasma and compare with TEG data.

METHODS

Hemophilia A (HA) was induced in platelet-rich plasma (PRP) from healthy volunteers, followed by spiking with FVIIa, γ-carboxyglutamic acid (Gla)-domainless FVIIa or V158D/E296V/M298Q-FVIIa (FVIIaDVQ). Samples were triggered with tissue factor and analyzed by TGA and TEG in parallel.

RESULTS

Addition of 25 nmol L-1 FVIIa to HA PRP normalized TEG parameters angle and R time, as well as TGA lag time, but had poor effects on the thrombin peak height and velocity index. All parameters (at least) returned to normal levels either upon adding a much higher concentration of FVIIa (~1500 nmol L-1) or by using the superactive variant FVIIaDVQ. Surprisingly, Gla-domainless derivatives of FVIIa and FVIIaDVQ also yielded considerable effects in HA PRP.

CONCLUSIONS

The good general responses to clinically effective concentrations of FVIIa (25 and 75 nmol L-1) seen in TEG analyses, as well as for TGA lag time, were accompanied by far-from-normal thrombin peaks. A near-normal thrombin peak response required the presence of considerably higher FVIIa activity but, intriguingly, relied only marginally on a functional Gla domain (ie, on platelet surface localization).

Evaluation of Global Hemostatic Assays in Response to Factor VIII Inhibitors

Global hemostatic assays including thromboelastography (TEG), Innovance ETP (endogenous thrombin potential), and Thrombinoscope could measure thrombin generation potential and be useful to guide management of patients with factor VIII (FVIII) inhibitors. However, the performance characteristics of these global assays in the presence of FVIII inhibitors are incompletely characterized. In this study, the normal range of thrombin generation potential was measured in 20 healthy individuals by all 3 assays. In 5 commercial and 7 clinical samples with FVIII inhibitors, it was shown that PPP-reagent thrombinoscope shows a dose-dependent response to different levels of FVIII inhibitors from the same patients, while Innovance ETP shows virtually no response to FVIII inhibitors. The TEG is more sensitive to FVIII inhibitors than thrombinoscope. Importantly, we show the same levels of FVIII inhibitor from different patients results in different levels of inhibition for thrombin generation potential by thrombinoscope, which potentially explains the phenotypic heterogeneity of patients with FVIII inhibitors. Global assays such as thrombinoscope, but not Innovance ETP, show appropriate sensitivity to FVIII inhibitors that could offer an objective and clinically relevant marker to guide patient management.

A novel, point-of-care, whole-blood assay utilizing dielectric spectroscopy is sensitive to coagulation factor replacement therapy in haemophilia A patients

BACKGROUND

Reliable monitoring of coagulation factor replacement therapy in patients with severe haemophilia, especially those with inhibitors, is an unmet clinical need. While useful, global assays, eg thromboelastography (TEG), rotational thromboelastometry (ROTEM) and thrombin generation assay (TGA), are cumbersome to use and not widely available.

OBJECTIVE

To assess the utility of a novel, point-of-care, dielectric microsensor - ClotChip - to monitor coagulation factor replacement therapy in patients with haemophilia A, with and without inhibitors.

METHODS

The ClotChip T_peak parameter was assessed using whole-blood samples from children with severe haemophilia A, with (n = 6) and without (n = 12) inhibitors, collected pre- and postcoagulation factor replacement therapy. ROTEM, TGA and chromogenic FVIII assays were also performed. Healthy children (n = 50) served as controls.

RESULTS

ClotChip T_peak values exhibited a significant decrease for samples collected postcoagulation factor replacement therapy as compared to baseline (pretherapy) samples in patients with and without inhibitors. A difference in T_peak values was also noted at baseline among severe haemophilia A patients with inhibitors as compared to those without inhibitors. ClotChip T_peak parameter exhibited a very strong correlation with clotting time (CT) of ROTEM, endogenous thrombin potential (ETP) and peak thrombin of TGA, and FVIII clotting activity.

CONCLUSIONS

ClotChip is sensitive to coagulation factor replacement therapy in patients with severe haemophilia A, with and without inhibitors. ClotChip T_peak values correlate very well with ROTEM, TGA and FVIII assays, opening up possibilities for its use in personalized coagulation factor replacement therapy in haemophilia.

Low thrombin generation predicts poor prognosis in ischemic stroke patients after thrombolysis

Thrombolysis by intravenous recombinant tissue plasminogen activator (rt-PA) is an effective therapy in acute ischemic stroke (AIS). Thrombin generation test (TGT) is a global hemostasis test providing information about the speed and amount of generated thrombin in plasma. Here we aimed to find out whether results of this test before the initiation of thrombolysis might predict outcomes. Study population included 120 consecutive AIS patients, all within 4.5 hours of their symptom onset, who underwent thrombolysis by rt-PA. Blood samples were collected from all patients upon admission and TGT was performed using platelet poor plasma. Clinical data of patients including the NIHSS were registered at admission, day 1 and 7 after therapy. The ASPECT score was assessed using CT images taken before and 24 hours after thrombolysis. Long-term functional outcome was defined 3 months after the event by the modified Rankin Scale. Endogenous Thrombin Potential (ETP) and Peak Thrombin were significantly lower in patients with cardioembolic IS. Symptomatic intracranial hemorrhage (SICH) was found in 6 patients and was significantly associated with low ETP and Peak Thrombin levels. A multiple logistic regression model revealed that an ETP result in the lower quartile is an independent predictor of mortality within the first two weeks (OR: 6.03; 95%CI: 1.2–30.16, p<0.05) and three months after the event (OR: 5.28; 95%CI: 1.27–21.86, p<0.05). Low levels of ETP and Peak Thrombin parameters increase the risk of therapy associated SICH. A low ETP result is an independent predictor of short- and long-term mortality following thrombolysis.

Acquired hemophilia A: Updated review of evidence and treatment guidance

Acquired hemophilia A (AHA) is a rare disease resulting from autoantibodies (inhibitors) against endogenous factor VIII (FVIII) that leads to bleeding, which is often spontaneous and severe. AHA tends to occur in elderly patients with comorbidities and is associated with high mortality risk from underlying comorbidities, bleeding, or treatment complications. Treatment, which consists of hemostatic management and eradication of the inhibitors, can be challenging to manage. Few data are available to guide the management of AHA-related bleeding and eradication of the disease-causing antibodies. Endorsed by the Hemostasis and Thrombosis Research Society of North America, an international panel of experts in AHA analyzed key questions, reviewed the literature, weighed the evidence and formed a consensus to update existing guidelines. AHA is likely underdiagnosed and misdiagnosed in real-world clinical practice. Recommendations for the management of AHA are summarized here based on the available data, integrated with the clinical experience of panel participants.

A general review of major global coagulation assays: thrombelastography, thrombin generation test and clot waveform analysis

Thrombosis and hemorrhage are major contributors to morbidity and mortality. The traditional laboratory tests do not supply enough information to diagnose and treat patients timely and according to their phenotype. Global hemostasis tests might improve this circumstance. The viscoelastic tests (ROTEM/TEG) demonstrated to ameliorate treatment of acute hemorrhage in terms of decreased amount of transfusion and lowered costs. Thrombin generation measurement is indicative for thrombosis and might also become an important tool in managing hemorrhage. While the clot waveform analysis is less well known it could be of worth in staging sepsis patients, early detection of DIC and also in diagnosis and treatment monitoring of hemophiliac patients. Although in different degree all three methods still need more background, standardization and acceptance before a wide clinical application.

A Comparison of Efficacy Between Recombinant Activated Factor VII (Aryoseven) and Novoseven in Patients With Hereditary FVIII Deficiency With Inhibitor

Introduction:

This study compared the efficacy of Aryoseven with Novoseven to control bleeding episodes in patients with hemophilia A with inhibitors.

Methods:

Sixty-six patients were randomized into 2 groups, with 4 consecutive block randomization. These groups received Aryoseven and Novoseven dosages of 90 to 120 μg/kg intravenously every 2 hours.

Results:

Median (interquartile range) level of factor VIII (FVIII) inhibitor in groups A and B was 15.0 and 19.0 Bethesda Unit (BU) preadministration. Bleeding onset in group A was 1246 ± 1104 minutes and in group B was 2301 ± 1693 minutes ( P = .311). The Kavakli global response scores and treatment success rate was comparable in both the groups. The side effects in groups A (9.7%) and B (2.9%) were comparable.

Conclusion:

Biosimilar recombinant activated FVII is found to be as effective as Novoseven in the treatment of acute joint bleeding in patients with hemophilia with inhibitors. Its usage will decrease the gaps in hemophilia.