A combined approach using global coagulation assays quickly differentiates coagulation disorders with prolonged aPTT and low levels of FVIII activity

Assessment of the phenotypic severity of hemophilia A: using rotational thromboelastometry (ROTEM) and APTT-clot waveform analysis

BACKGROUND

Hemophilia A (HA) is an X-linked inherited bleeding disorder caused by reduced factor VIII (FVIII) levels. Approximately 10-15% of patients with severe HA (SHA) do not present with the anticipated bleeding pattern. Here, we assessed the phenotypic severity of hemophilia A using rotational thromboelastometry (ROTEM) and activated partial thromboplastin time-clot waveform analysis (APTT-CWA).

METHODS

Patients diagnosed with hemophilia A were enrolled. Clinical phenotype assignment was performed according to the published literature, and patients were classified into four phenotypic subgroups. The whole blood sample was first run on ROTEM in INTEM mode using platelet-poor plasma, APTT was run, and the APTT-CWA graph was simultaneously recorded.

RESULTS

A total of 66 patients were recruited for this study. Statistically significant differences were observed between the four phenotypically categorized groups using ROTEM and APTT-CWA. On comparing patients with mild/moderate-to-severe phenotypes (Group II) with SHA without inhibitors (Group IV), no significant difference was found for all parameters of ROTEM or APTT-CWA. The MCF, MA30, MAXV, and Alpha angle values using ROTEM were found to be the lowest in patients with SHA with inhibitors, which helped differentiate them from those with SHA without inhibitors. However, these two groups could not be differentiated using the APTT-CWA parameters.

CONCLUSION

ROTEM can be used to distinguish patients with SHA with inhibitors from those with SHA without inhibitors using a combination of parameters with high sensitivity and specificity. However, APTT-CWA cannot be used to differentiate these patient groups.

ROTEM could be useful for lupus anticoagulant hypoprothrombinemia syndrome

BACKGROUND

Lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS) is a rare disease caused by acquired factor II (FII) deficiency and lupus anticoagulant. Patients with LAHPS typically present with thrombosis and bleeding. However, little information is available on the evaluation of coagulation potential in patients with LAHPS. We examined global coagulation potentials in patients with LAHPS during the clinical course in this study.

METHODS

Coagulation potentials in two pediatric patients with LAHPS were assessed by measuring clotting time (CT) and clot formation time using Ca2+-triggered rotational thromboelastometry (ROTEM), CT and maximum coagulation velocity using clot waveform analysis (CWA), and lag time and peak thrombin using the thrombin generation assay (TGA). The day of admission was defined as day 0.

RESULTS

In case 1, the bleeding symptoms disappeared by day 5. However, the TGA and CWA results were markedly lower than normal, although FII activity (FII:C) returned to within the normal range by day 14. In contrast, ROTEM revealed a recovery to near-normal levels (day 14). All coagulation parameters (day 80) were within normal ranges. In case 2, coagulation potential was severely depressed until day 12, although FII:C returned to normal levels. Bleeding symptoms disappeared on day 19, and the ROTEM data revealed that the parameters were close to the normal range. The coagulation parameters in all assays were normalized on day 75.

CONCLUSIONS

Recovery of coagulation potential in patients with LAHPS was slower than the recovery of FII:C. Moreover, ROTEM appeared to be clinically useful for assessing coagulation potential in patients with LAHPS.

Characterization and Usefulness of Clot-Fibrinolysis Waveform Analysis in Critical Care Patients with Enhanced or Suppressed Fibrinolysis

INTRODUCTION

 Recently, clot-fibrinolysis waveform analysis (CFWA), which is a coagulation and fibrinolysis global assay based on assessing the activated partial thromboplastin time with tissue-type plasminogen activator, was developed. This study aimed to investigate the characteristics of CFWA using plasma samples from patients in the critical care unit.

MATERIALS AND METHODS

 The fibrinolysis times using CFWA were measured in 298 plasma samples. These samples were divided into three groups based on the reference interval (RI) of fibrinolysis time using CFWA: shortened group, less than RI; within group, within RI; prolonged group, more than RI. The coagulation and fibrinolysis markers, including D-dimer, plasmin-α2 plasmin inhibitor complex (PIC), fibrin monomer complex (FMC), plasmin-α2 plasmin inhibitor (α2-PI), plasminogen (Plg), and fibrinogen (Fbg) were analyzed and compared among the three groups.

RESULTS

 The FMC level decreased in the order of shortened, within, and prolonged groups, and the decrease was statistically significant among all three group pairs. The opposite tendency was observed for Fbg and fibrinolysis-related markers of α2-PI and Plg, and significant differences were recognized in all pair comparisons except for between within and prolonged groups in Plg. The mean values of the fibrinolysis markers D-dimer and PIC in all three groups were higher than the cut-off values, and the PIC value differed significantly between the within and prolonged groups.

CONCLUSION

 The fibrinolysis reaction was detected in all three groups, but the status differed. CFWA has the potential to reflect the fibrinolysis status in one global assay.

Comprehensive comparison of global coagulation assays to differentiate lupus anticoagulant from acquired hemophilia A in patients with prolonged APTT

There is no established method for differentiating acquired hemophilia A (AHA) from lupus anticoagulant (LA) positivity because both present with prolonged activated partial thromboplastin time. We compared various parameters of rotational thromboelastometry (ROTEM), thrombin generation assay (TGA), and clot waveform analysis (CWA) in patients with AHA (n = 10) and LA (n = 44). Compared with AHA, possible (n = 12) and definite (n = 32) LA showed significantly shorter clotting time (CT) in NATEM mode of ROTEM (> 3600 vs. 501/533). In TGA, peak height was significantly lower in AHA (16 vs. 242/174 nM). In CWA, CT was significantly longer (81 vs. 36/41 s) and Ad|min1| was lower (2.1 vs. 8.7/6.7) in AHA. Notably, CT by NATEM and peak height in TGA completely discriminated between AHA and LA, whereas Ad|min1| did not discriminate between them in 4 cases of AHA and 1 of LA. Comparison of 3 patients with both AHA and LA against a patient with only LA and markedly low FVIII activity (3.5%) showed that both CT by NATEM and peak height of TGA precisely classified the former 3 cases as AHA and the latter 1 case as LA, whereas Ad|min1| classified all 4 cases as AHA. ROTEM and TGA can comparably distinguish between AHA and LA.

The Evaluation of Clot Waveform Analyses for Assessing Hypercoagulability in Patients Treated with Factor VIII Concentrate

BACKGROUND

Regular prophylactic therapy has become an increasingly common treatment for severe hemophilia. Therefore, hypercoagulability-a potential risk factor of thrombosis-is a cause for concern in hemophilic patients treated with a high dose of FVIII concentrate. In clot waveform analysis (CWA)-thrombin time (TT), a small amount of thrombin activates clotting factor VIII (FVIII) instead of fibrinogen, resulting in FVIII measurements using CWA-TT with a small amount of thrombin.

METHODS

The coagulation ability of patients treated with FVIII concentrate or emicizumab was evaluated using activated partial thromboplastin time (APTT), TT and a small amount of tissue factor-induced FIX activation assay (sTF/FIXa) using CWA.

RESULTS

The FVIII activity based on CWA-TT was significantly greater than that based on the CWA-APTT or chromogenic assay. FVIII or FVIII-like activities based on the three assays in plasma without emicizumab were closely correlated; those in plasma with emicizumab based on CWA-TT and chromogenic assays were also closely correlated. CWA-APTT and CWA-TT showed different patterns in patients treated with FVIII concentrates compared to those treated with emicizumab. In particular, CWA-TT in patients treated with FVIII concentrate showed markedly higher peaks in platelet-rich plasma than in platelet-poor plasma. CWA-APTT showed lower coagulability in hemophilic patients treated with FVIII concentrate than in healthy volunteers, whereas CWA-sTF/FIXa did not. In contrast, CWA-TT showed hypercoagulability in hemophilic patients treated with FVIII concentrate.

CONCLUSIONS

CWA-TT can be used to evaluate the thrombin bursts that cause hypercoagulability in patients treated with emicizumab. Although routine APTT evaluations demonstrated low coagulation ability in patients treated with FVIII concentrate, CWA-TT showed hypercoagulability in these patients, suggesting that the evaluation of coagulation ability may be useful when using multiple assays.

Clot Waveform Analysis for Monitoring Hemostasis

Clot waveform analysis (CWA) is a recently developed global coagulation assessment, based on the continuous observation of changes in light transmittance, absorbance, or light scattering that occurs as fibrin formed in a plasma sample during routine clotting tests such as activated partial thromboplastin time (aPTT) and prothrombin time (PT). CWA can utilize qualitative waveform patterns as well as sensitive quantitative parameters and can be used as a simple method to assess global hemostasis, and can be applied to various challenging clinical situations. Although not all coagulation analyzers currently in use are able to provide CWA, the number of analyzers available to do so is increasing, as the usefulness of this process has become more widely recognized. CWA can be based on the coagulation mechanism of aPTT, an intrinsic trigger, and this has been reported in many studies, including diagnosis and treatment of patients with hemophilia, disseminated intravascular coagulation, and monitoring of anticoagulants and thrombosis. CWA using trace amounts of tissue factors also has the potential to expand the applications of this technology. Recently, there have been reports of the combined evaluation of fibrinolytic dynamics. Among the existing global coagulation assays, CWA may prove to be the easiest to standardize in clinical practice. However, more extensive testing using standardized methods in various clinical settings is needed to determine the true role of CWA in the evaluation of hemostasis and thrombosis in the future.

Application of the thrombin generation assay in patients with antiphospholipid syndrome: A systematic review of the literature

Background

The antiphospholipid syndrome (APS) is classified by the presence of antiphospholipid antibodies (aPL) and thrombotic and/or adverse obstetric outcomes. The diagnosis and risk assessment of APS is challenging. This systematic review investigated if the thrombin generation (TG) assay could be helpful for APS diagnosis and risk assessment.

Methods

A systemic review was performed by searching two databases (MEDLINE and Embase) until March 31, 2022, using a search strategy with two concepts: APS and TG, and related keywords. Two reviewers independently screened the articles based on predefined inclusion and exclusion criteria. Data extraction and quality assessment with the Newcastle-Ottawa Scale (NOS) were performed independently. Synthesis Without Meta-analysis guidelines were followed for data synthesis reporting.

Results

Fourteen studies with 677 APS and 1,349 control subjects were included with variable quality according to the NOS. Twelve studies measured TG via the calibrated automated thrombogram (CAT) method using a fluorogenic substrate, whereas two used a chromogenic substrate-based TG assay. One study compared the CAT assay to the fully-automated ST Genesia® (Stago, France). Two studies initiated TG using platelet-rich plasma, whereas the rest of the studies used platelet-poor plasma. Resistance to activated protein C (aPC) was examined in ten studies. They reported a significant increase in aPC-resistance in APS patients compared to healthy controls, aPL-carriers, and thrombotic controls. Based on two studies, the prevalence of aPC-resistance was higher in APS patients compared to healthy controls and thrombotic controls with odds ratios of 5.9 and 6.8–12.8, respectively (p < 0.05). In contrast, no significant difference in aPC-resistance was found between APS patients and autoimmune disease controls. Furthermore, 7/14 studies reported TG-parameters including peak height, endogenous thrombin potential, lag time, and time to peak, but these outcomes were highly variable between studies. Furthermore, TG methodology between studies differed greatly, impacting the comparability of the studies.

Conclusion

aPC-resistance measured with TG was increased in APS patients compared to healthy and thrombotic controls, but the diagnostic and prognostic value is unclear compared to current diagnostic strategies. Studies of other TG-parameters were heterogeneous and more research is needed to identify their potential added value in APS diagnosis.

Systematic Review Registration

https://www.PROSPERO/, identifier: CRD42022308363

Screening of the protein C pathway abnormality-related thrombophilia by using thrombomodulin-mediated tissue factor-triggered clot waveform analysis

OBJECTIVES

Absolute or relative protein (P)C pathway abnormalities (PC deficiency, PS deficiency, antiphospholipid syndrome (APS), factor (F)V-abnormality, and high FVIII level) cause thrombophilia. Although screening assays for these thrombophilias are available, one utilizing clot waveform analysis (CWA) remains unknown. We aimed to establish a CWA-based screening assay to distinguish PC pathway abnormality-related thrombophilia.

METHODS

Samples were reacted with tissue factor (TF)/phospholipids and recombinant thrombomodulin (rTM; optimal 20 nM), followed by CWA measurement. The peak ratio (with/without rTM) of the first derivative curve of clot waveform was calculated.

RESULTS

The peak ratio in healthy plasmas (n = 35) was 0.36 ± 0.13; hence, the cutoff value was set to 0.49. The peak ratios in plasmas with PC deficiency, PS deficiency, high-FVIII (spiked 300 IU/dl), and APS were higher than the cutoff values (0.79/0.97/0.50/0.93, respectively). PC-deficient plasma or PS-deficient plasma mixed with normal plasma (25%/50%/75%/100% PC or PS level) showed dose-dependent decreases in the peak ratios (PC deficient: 0.85/0.64/0.44/0.28; PS deficient: 0.69/0.53/0.40/0.25), suggesting that the peak ratio at ≤50% of PC or PS level exceeded the cutoff value. The peak ratio in FV deficiency with FV ≤25% was higher than the cutoff value. FV-deficient plasma spiked with 40 IU/dl rFV-R506Q (FV_Leiden ) or rFV-W1920R (FV_Nara ) showed >90% peak ratios.

CONCLUSIONS

rTM-mediated TF-triggered CWA might be useful for screening PC pathway abnormality-related thrombophilia.

Clot Waveform Analysis Demonstrates Low Blood Coagulation Ability in Patients with Idiopathic Thrombocytopenic Purpura

BACKGROUND

Although platelets, which contain large amounts of phospholipids, play an important role in blood coagulation, there is still no routine assay to examine the effects of platelets in blood coagulation.

METHODS

Hemostatic abnormalities in patients with thrombocytopenia, including those with idiopathic thrombocytopenic purpura (ITP), were examined using clot wave analysis (CWA)-small-amount tissue-factor-induced FIX activation (sTF/FIXa) and thrombin time (TT).

RESULTS

Although there were no marked differences in the three parameters of activated partial thromboplastin time (APTT) between normal healthy volunteers and typical patients with ITP, the peak heights of the CWA-sTF/FIXa were markedly low in patients with ITP. The three peak times of the CWA-sTF/FIXa in patients with a platelet count of ≤8.0 × 10¹⁰/L were significantly longer than those in patients with a platelet count > 8.0 × 10¹⁰/L and the peak heights of the CWA-sTF/FIXa in patients with a platelet count of ≤8.0 × 10¹⁰/L were significantly lower than those in patients with >8.0 × 10¹⁰/L. The peak heights of the CWA-APTT in patients with ITP were significantly lower than in patients with other types of thrombocytopenia. The three peak heights of the CWA-sTF/FIXa in ITP patients were significantly lower than those in patients with other types of thrombocytopenia. The CWA-TT showed lower peak heights and longer peak times in patients with ITP in comparison to patients with other types of thrombocytopenia.

CONCLUSIONS

The CWA-sTF/FIXa and CWA-TT results showed that blood coagulation is enhanced by platelets and that the blood coagulation ability in ITP patients was low in comparison to healthy volunteers and patients with other types of thrombocytopenia.

The Reevaluation of Thrombin Time Using a Clot Waveform Analysis

Object: Although thrombin burst has attracted attention as a physiological coagulation mechanism, clinical evidence from a routine assay for it is scarce. This mechanism was therefore evaluated by a clot waveform analysis (CWA) to assess the thrombin time (TT). Material and Methods: The TT with a low concentration of thrombin was evaluated using a CWA. We evaluated the CWA-TT of plasma deficient in various clotting factors, calibration plasma, platelet-poor plasma (PPP), and platelet-rich plasma (PRP) obtained from healthy volunteers, patients with thrombocytopenia, and patients with malignant disease. Results: Although the TT-CWA of calibration plasma was able to be evaluated with 0.01 IU/mL of thrombin, that of FVIII-deficient plasma could not be evaluated. The peak time of CWA-TT was significantly longer, and the peak height significantly lower, in various deficient plasma, especially in FVIII-deficient plasma compared to calibration plasma. The second peak of the first derivative (1st DP-2) was detected in PPP from healthy volunteers, and was shorter and higher in PRP than in PPP. The 1st DP-2 was not detected in PPP from patients with thrombocytopenia, and the 1st DP-2 in PRP was significantly lower in patients with thrombocytopenia and significantly higher in patients with malignant disease than in healthy volunteers. Conclusion: The CWA-TT became abnormal in plasma deficient in various clotting factors, and was significantly affected by platelets, suggesting that the CWA-TT may be a useful test for hemostatic abnormalities.

Coagulation, Vascular Morphology, and Vasculogenesis in Spinal Ligament Ossification Model Mice

STUDY DESIGN

In vivo studies of the vascular system in ossification of the posterior longitudinal ligament (OPLL) model mice.

OBJECTIVE

The aim of this study was to investigate blood coagulability, vascular morphology, and vasculogenesis capability, known as venous thromboembolism (VTE) risk factors in the ossification model, tiptoe walking (ttw) mice.

SUMMARY OF BACKGROUND DATA

Patients with OPLL are more likely to develop VTE after spinal cord injury. Capillary mesh invasion of spinal ligaments precedes spinal ligament ossification in ttw mice. Investigation on vascular systems of ttw mice may contribute to clarifying its pathology.

METHODS

Coagulability of blood samples from ttw and C57BL/6 (WT) mice were evaluated at 8, 16, and 24 weeks of age. Vascular morphology was assessed from a Hematoxylin-Eosin stained section by measuring vessel area. A tube formation assay was performed with endothelial cells isolated from the aorta to assess vasculogenesis.

RESULTS

Prothrombin time was significantly shorter in ttw mice than in WT at 8 and 16 weeks. Fibrinogen had a greater increase in ttw mice than in WT at 16 weeks. The vascular area and vascular wall area were significantly smaller in ttw mice than in WT at all timepoints. The ratio of vascular wall area to vascular area was significantly smaller in ttw mice than in WT at 24 weeks. The endothelial cells from ttw mice formed significantly higher numbers of total branching points than WT cells.

CONCLUSION

Ossification model mice had impaired blood coagulation and vascular morphology and high capacity for vasculogenesis. With regard to the pathogenesis of VTE, ttw mice harbor an environment that promotes the development of VTE.Level of Evidence: N/A.

Update on the Clot Waveform Analysis

The activated partial thromboplastin time (APTT)–clot waveform analysis (CWA) was previously reported to be associated with the early detection of disseminated intravascular coagulation and was also reported to be able to measure very low levels of coagulation factor VIII activity. The software program for the analysis for the APTT-CWA allows the associated first and second derivative curves (first and second DCs) to be displayed. The first and second DC reflect the velocity and acceleration, respectively. The height of the first DC reflects the “thrombin burst” and bleeding risk, while that of the second DC is useful for detecting any coagulation factor deficiency and abnormal enhancement of coagulation by phospholipids. Activated partial thromboplastin time-CWA aids in making a differential diagnosis which is difficult to do using only the routine APTT. The CWA is currently used for many applications in the clinical setting, including the monitoring of hemophilia patients and patients receiving anticoagulant therapy and the differential diagnosis of diseases.

The Evaluation of Hemostatic Abnormalities Using a CWA-Small Amount Tissue Factor Induced FIX Activation Assay in Major Orthopedic Surgery Patients

We analyzed the utility for a clot waveform analysis (CWA) of small tissue factor induced FIX activation (sTF/FIXa) assay in patients with major orthopedic surgery (including total hip arthroplasty [THA] and total knee arthroplasty [TKA]) receiving edoxaban for the prevention of venous thromboembolism (VTE). The sTF/FIXa assay using recombinant human TF in platelet-rich plasma (PRP) and platelet-poor plasma (PPP) was performed using a CWA in the above patients to monitor the efficacy of edoxaban administration. Of 147 patients (109 THA and 38 TKA), 21 exhibited deep vein thrombosis (DVT), and 15 had massive bleeding. Increased peak heights of the CWA-sTF/FIX were observed in almost patients after surgery and prolonged peak heights of the CWA-sTF/FIX were observed in almost patients treated with edoxaban. The peak heights and times of the CWA-sTF/FIX were significantly higher and shorter, respectively, in PRP than in PPP. There were no significant differences in parameters of the CWA-sTF/FIXa between the patients with and without DVT or between those with and without massive bleeding. The peak time of CWA-sTF/FIXa were significantly longer in TKA patients than in THA patients on day 1 after surgery. The second derivative peak height of the CWA-sTF/FIXa was significantly lower in TKA patients than in THA patients on day 4. The CWA-sTF/FIX reflected hemostatic abnormalities after surgery and the administration of edoxaban, and the results were better in PRP than PPP. Further studies separately analyzing the THA and TKA subgroups should be conducted.

Evaluation of hemostatic abnormalities in patients who underwent major hepatobiliary pancreatic surgery using activated partial thromboplastin time-clot waveform analysis

INTRODUCTION

Bleeding after major hepatobiliary pancreatic (HBP) surgery may be serious. Although postoperative abnormality of the hemostatic system are important elements that affect bleeding, routine activated partial thromboplastin time (APTT) assessment is considered inadequate to predict massive bleeding (MB). Recently, APTT-clot waveform analysis (CWA) was reported to be useful for detecting coagulation disorders.

METHODS

APTT-CWA was performed using the ACL-TOP analyzer in 188 patients who underwent four major HBP surgeries (distal pancreatectomy, hepatectomy, subtotal stomach-preserving pancreatoduodenectomy (SSPPD), and SSPPD with combined resection and reconstruction of the portal vein) to analyze its usefulness in predicting the risk of bleeding.

RESULTS

Seventy (37.2%) patients developed MB and the incidence of MB was highest among patients who underwent hepatectomy. There were no significant differences in routine APTT, the first derivative peak (DP) time and 1/2 fibrin formation peak time between patients with MB and those without MB, throughout the postoperative course. On the other hand, the first and second DP heights were significantly lower in patients with MB than in those without MB and lowest in patients who underwent hepatectomy.

CONCLUSION

APTT-CWA was able to detect the detailed changes in the hemostatic system after major HBP surgery. The patterns of APTT-CWA after major HBP surgery differed among various surgical procedures according to invasiveness. The lower first and the second DP height, which were frequently observed in hepatectomy patients, may be useful for predicting the risk of MB.

Lupus anticoagulant hypoprothrombinemia syndrome associated with bilateral adrenal haemorrhage in a child: early diagnosis and intervention

BACKGROUND

Lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS) is characterized by bleeding and thrombosis in patients with autoimmune diseases or infections. Paediatric LAHPS exhibits various degrees of bleeding, ranging from mild to severe; however, adrenal haemorrhage due to LAHPS and its long-term clinical course have not been sufficiently described.

CASE PRESENTATION

A 9-year-old boy presented with prolonged abdominal pain and abnormal coagulation screening tests. The laboratory tests showed prolonged activated partial thromboplastin time and subsequently revealed the presence of lupus anticoagulant, anti-nuclear antibodies, and hypoprothrombinemia, leading to diagnosis of LAHPS. An enhanced computed tomogram demonstrated nodular lesions in the adrenal glands bilaterally, suggestive of adrenal haemorrhage. Laboratory and clinical manifestations exhibited life-threatening adrenal insufficiency that required hydrocortisone administration. The patient developed systemic lupus erythematosus, diagnosed 12 months later.

CONCLUSIONS

This patient with LAHPS developed rare adrenal failure due to adrenal haemorrhage, a life-threatening event that should be recognized and treated early. In our case, renal dysfunction was also observed when systemic lupus erythematosus was diagnosed 1 year after LAHPS. Our case emphasizes that early recognition of adrenal failure and careful long-term observation is required in patients with autoantibodies.

The Evaluation of APTT Reagents in Reference Plasma, Recombinant FVIII Products; Kovaltry® and Jivi® Using CWA, Including sTF/7FIX Assay

The FVIII activity in patients treated with several extended half-life FVIII (EHL-FVIII) agents different when various activated partial thromboplastin time (APTT) reagents were used. The present study examined the difference in clot waveform analysis (CWA) findings and FVIII activity when various APTT reagents and CWA were used. The CWA including FVIII activity was measured using 12 APTT reagents, and the FIX activation based on a small amount of tissue factor assay (sTF/FIX) were examined in reference plasma (RP), EHL-FVIII (Jivi^®) and Kovaltry^®. The 3 APTT reagents were associated with high variation in the peak time and height in the CWA when analyzing low concentrations of FVIII. The peak time and height could not be measured with one APTT reagent, and there were marked differences in the CWA findings between Jivi^® and Kovaltry^® among APTT reagents. Several APTT reagents showed a markedly lower FVIII activity with Jivi^® than with Kovaltry^®. In the FVIII assay, the peak time measured with sTF/FIX did not differ markedly between Jivi^® and Kovaltry^®; however, the FVIII activity in Jivi^® (as measured by the peak height) tended to be higher than in Kovaltry^®. The CWA findings for monitoring Jivi^® varied for monitoring Jivi^® depending on the APTT reagents used, and sTF/FIX assay may be able to measure the EHL-FVIII.

Inhibitor Index in the Clot Waveform Analysis-Based Mixing Test Differentiates among Hemophilia A without and with Inhibitors, and Lupus Anticoagulant

BACKGROUND

 The mixing test is used to identify the pathway to follow-up testing and is also useful for the investigation of lupus anticoagulant (LA) positivity. "To completely correct" indicates clotting factor deficiency, while "to not correct" indicates the presence of a clotting factor inhibitor including LA. "Index of circulation anticoagulant" and/or "percent correction" is used to interpret the results of mixing studies, but it does not accurately differentiate factor inhibitors from LA.

AIM

 To precisely differentiate hemophilia A (HA), HA with inhibitor (HA-inh), and LA using the clot waveform analysis (CWA)-based mixing test.

METHODS

 Plasma samples from HA, LA, and HA-inh including acquired HA were incubated with normal plasma in 9:1, 1:1, and 1:9 mix ratios. From activated partial thromboplastin time CWA at 0-minute (immediately) and 12-minute incubation, the ratios of CWA parameters at 12 minutes/0 minute (inhibitor index) were assessed.

RESULTS

 The inhibitor index values of CWA parameters obtained using the mixing test in a 1:1 ratio demonstrated a significant difference between HA-inh and LA but could not differentiate LA from HA-inh completely. Plasmas used for the mixing tests in 9:1 and 1:9 ratios were able to fully distinguish between HA-inh (>0.5 BU/mL) and LA. These indices significantly correlated with inhibitor titer below 40 BU/mL (r > 0.90), possibly estimating FVIII inhibitor titer from the inhibitor index. Plasmas in HA and LA could be distinguished by mixing in a 1:1 ratio at 0 minute (immediately).

CONCLUSION

 The inhibitor index from CWA-based mixing tests with a 12-minute incubation could differentiate among HA, HA-inh, and LA quickly.

A Novel Assessment of Factor VIII Activity by Template Matching Utilizing Weighted Average Parameters from Comprehensive Clot Waveform Analysis

BACKGROUND

 Activated partial thromboplastin time (aPTT)-based clot waveform analysis is used to evaluate the comprehensive dynamics of fibrin clot formation. In addition, the technique can be usefully utilized for the rapid assessment of factor (F)VIII procoagulant activity in various clinical settings in patients with hemophilia A (HA). We defined a novel algorithm based on the weighted average parameters from aPTT-based waveforms to devise a template-matching procedure for assessing FVIII activity (FVIII:C).

METHODS

 The first derivatives of original clot waveforms triggered by the aPTT reagent (Coagpia APTT-N) were used to determine weighted averages of areas surrounded by the waveform at different percentages of maximum height in various clotting factor-deficient plasmas. Prepared templates based on 50 weighted average-related parameters were compared with 78 aPTT-prolonged plasmas.

RESULTS

 Original nonsmoothed waveforms of the various clotting factor-deficient plasmas with prolonged aPTTs demonstrated a variety of shapes. The weighted averages were calculated after adjustments for different baselines, and the patterns seemed to be governed by the specific clotting factor deficiency. The weighted average-related parameters including baseline wedge (r ² = 0.998) and aspect ratio (r ² = 0.998) were highly correlated with FVIII:C levels. Template-matching analyses based on weighted average-related waveform parameters obtained from 158 samples demonstrated that the sensitivity was 97.2% and specificity was 83.3% in aPTT-prolonged plasmas (n = 78).

CONCLUSION

 This novel algorithm based on weighted averages of aPTT-based waveforms together with template-matching may support clinical usefulness for judging of HA and may aid clinical management in the patients in the absence of specific clotting factor assays.

Effects of platelet and phospholipids on clot formation activated by a small amount of tissue factor

INTRODUCTION

Physiological coagulation is considered to activate coagulation factor IX (FIX) by a small amount of tissue factor (TF) and activated coagulation factor VII (FVIIa) with the presence of platelets. A Clot waveform analysis (CWA) may be useful for evaluating physiological coagulation.

MATERIAL AND METHODS

A CWA using a small amount of TF (CWA/sTF) was performed in platelet-rich plasma (PRP), platelet-poor plasma (PPP), several phospholipids (PLs) and patients with lupus anticoagulant (LA), idiopathic thrombocytopenic purpura (ITP) or inhibitor for FVIII.

RESULTS

The CWA/sTF without PLs showed a shorter peak time and higher peak height in PRP than in PPP. The effect of PRP on the CWA/sTF depended on the platelet count, and PLs showed a similar effect on the CWA/sTF results in PPP. The peak time of the CWA/sTF in PRP was prolonged in patient with ITP. The CWA/sTF in PRP showed a prolonged peak time and decreased peak height of the second derivative in patient with LA. Both a shortened peak time and elevated peak height were observed in the CWA/sTF of patient with inhibitor after treatment with activated recombinant human FVII.

CONCLUSION

A CWA can be conducted using a small amount of TF and platelets or PL without contact activation and may be able to detect not only hemostatic abnormalities but also changes in platelet counts.

Usefulness of the APTT waveform for the diagnosis of DIC and prediction of the outcome or bleeding risk

Background

The usefulness of the activated partial thromboplastin time (APTT) waveform has been reported in hemophilia, acquired hemophilia and monitoring for anticoagulants.

Material and methods

The APTT waveform was examined in patients suspected of having disseminated intravascular coagulation (DIC) to analyze its usefulness for the diagnosis of DIC or the prediction of the outcome or bleeding risk.

Results

DIC with fibrinogen < 2 g/L was frequently associated with infectious diseases (43.3%). The heights of the first derivative peak (1stDP) and second DP (2ndDP) were extremely low in DIC, especially DIC with hypofibrinogenemia, but high in infectious patients without DIC. The peak time and width of the 1stDP and 2ndDP were prolonged in patients with DIC. The heights of the 1^stDP and 2^ndDP were markedly low in patients with a poor outcome or those with hemoglobin < 8.0 g/dl.

Discussion and conclusion

As bleeding type DIC was observed in infectious DIC, DIC without hypofibrinogenemia might switch to DIC with hypofibrinogenemia by the progression of DIC. The height of the 1^stDP and 2^ndDP is useful for the diagnosis of DIC and prediction of the bleeding risk or outcome.

An Evaluation of Hemostatic Abnormalities in Patients With Hemophilia According to the Activated Partial Thromboplastin Time Waveform

The usefulness of the waveform of activated partial thromboplastin time (APTT) in various diseases has been evaluated in recent years. The APTT waveform was examined in patients with hemophilia and patients positive for lupus anticoagulant (LA). The correlation with the FVIII activity was highest for the height of acceleration peak. The peak time of acceleration, velocity, and ½ fibrin formation, and the width of acceleration and velocity were significantly long and the height of acceleration was significantly low in patients with hemophilia. The height of velocity was significantly low in patients with hemophilia with inhibitor. There were no significant differences in the APTT waveform between patients with hemophilia and patients with LA, but the peak of acceleration and ½ fibrin formation were significantly longer and the height of acceleration and velocity were significantly lower in patients with hemophilia with inhibitor than in the patients with LA. Wave changes in the APTT were observed in all 22 patients positive for LA, while a biphasic waveform was observed in patients with hemophilia with FVIII activity <10.0%. The APTT waveform is useful for the analysis of hemostatic abnormalities in patients with hemophilia.

An Evaluation of the Activated Partial Thromboplastin Time Waveform

The activated partial thromboplastin time (APTT) waveform includes several parameters that are related to various underlying diseases. The APTT waveform was examined in various diseases. Regarding the pattern of APTT waveform, a biphasic pattern of the first or second derivative curve (DC) was observed in patients with hemophilia and patients positive for antiphospholipid (aPL) antibodies or coagulation factor VIII (FVIII) inhibitors. The time of the first and second DC and fibrin formation at 1/2 height were prolonged in patients with hemophilia, patients with inhibitors, patients positive for aPL, patients treated with anti-Xa agents, and patients with disseminated intravascular coagulation (DIC). These values all tended to decrease in pregnant women (at 28-36 weeks' gestation). The height of the second derivative peak 1 was significantly lower in patients with hemophilia, patients with FVIII inhibitors, patients positive for aPL, patients treated with anti-Xa agents, and patients with DIC; these values tended to be significantly higher in pregnant women. The height of the first DC was significantly lower in patients who were positive for FVIII inhibitors and was significantly higher in patients treated with anti-Xa agents and pregnant women. The height of the first and second DC was useful for the analysis of hemophilia, FVIII inhibitor, and aPL.

Clot waveform analysis: Where do we stand in 2017?

Analysis of the optical waveform generated during global coagulation assays, such as activated partial thromboplastin time and prothrombin time, can provide much precious information on the global coagulation state of the plasma sample tested, in addition to a single clotting time. Many studies have been published concerning patient diagnosis and management in haemophilia A, and in the early diagnosis and prognosis of disseminated intravascular coagulation and sepsis. However, many other works have also been published on further potential clinical applications such as lupus anticoagulant diagnosis and anticoagulant monitoring. Altogether, these publications have demonstrated the ability for clot waveform analysis (CWA) to improve patient management, especially as this tool is inexpensive, rapid and readily available on coagulation analysers with optical detection systems. By an extensive review of the literature related to studies performed on CWA, this publication aims at providing a review of current knowledge in this specific field, ranging from research data to potential clinical applications and future trends.

Monitoring of hemostatic abnormalities in major orthopedic surgery patients treated with edoxaban by APTT waveform

INTRODUCTION

An analysis of the activated partial thromboplastin time (APTT) in major orthopedic surgery patients receiving edoxaban for the prevention of venous thromboembolism (VTE) was carried out.

METHODS

The APTT waveform was analyzed in the above patients to monitor edoxaban administration.

RESULTS

Of these 99 patients, 12 exhibited deep vein thrombosis, and 25 had massive bleeding. An increased biphasic pattern of the APTT waveform was observed after the administration of edoxaban, but there were no significant differences between the patients with and without complications. The peak times of acceleration, velocity, and 1/2 fibrin formation were significantly prolonged after the administration of edoxaban, especially in patients with massive bleeding, and were moderately correlated with the anti-Xa activity. While the heights of velocity and acceleration peak 2 were lower in patients receiving warfarin treatment than in those receiving edoxaban, the widths of these parameters were significantly longer. The height of 1/2 fibrin formation and the width of acceleration peaks 1 and 2 and the velocity were significantly increased after the administration of edoxaban.

CONCLUSION

The peak time of the APTT waveform was significantly prolonged after the administration of edoxaban. The analysis of the APTT waveform may therefore be useful for the prediction of the risk of massive bleeding.