Assessment of Platelet Aggregation and Thrombin Generation in Patients with Familial Chylomicronemia Syndrome Treated with Volanesorsen: A Cross-Sectional Study.

BACKGROUND: The antisense oligonucleotide against APOC3 mRNA volanesorsen was recently introduced to treat Familial Chylomicronemia Syndrome (FCS). Cases of decreased platelet count are reported among patients treated with volanesorsen. The aim of the study was to evaluate platelet function and thrombin generation (TG) assessment in FCS patients receiving volanesorsen. We performed a cross-sectional study on FCS patients treated with volanesorsen. METHODS: Changes in platelet count PLC were assessed from baseline to Tw12 and Tw36. To assess TG, samples were processed by CAT (with PPP-reagent LOW). The results were expressed by the thrombogram graphic (thrombin variation over time); LagTime; endogenous thrombin potential (ETP); peak; time to reach peak (ttpeak), StartTail and Velocity Index. Platelet aggregation was assessed by testing different agonists using the turbidimetry method. RESULTS: Four FCS patients and four matched healthy controls were included in the present study. Changes in PLC were 30% at Tw12 and 34% at Tw36. Thrombin generation results showed values in the normal range (for patients and controls, respectively, LagTime:10.42 ± 4.40 and 9.25 ± 0.99; ttPeak:14.33 ± 4.01 and 13.10 ± 0.67; StartTail: 32.13 ± 3.54 and 29.46 ± 1.69; Velocity Index: 20.21 ± 3.63 and 33.05 ± 13.21; ETP: 599.80 ± 73.47 and 900.2 ± 210.99; peak value: 76.84 ± 1.07 and 123.30 ± 39.45) and no significant difference between cases and controls. Platelet aggregation test showed values in range, with no significant difference compared to healthy controls. CONCLUSIONS: Our study showed for the first time that no significant changes in general hemostasis assessed by TG and in platelet function were observed in FCS patients receiving volanesorsen.

Direct oral anticoagulants in cirrhosis: Rationale and current evidence.

Cirrhosis is a major health concern worldwide with a complex pathophysiology affecting various biological systems, including all aspects of haemostasis. Bleeding risk is mainly driven by portal hypertension, but in end-stage liver disease it is further increased by alterations in haemostatic components, including platelet function, coagulation, and fibrinolysis. Concurrently, patients with cirrhosis are prone to venous thromboembolic events (VTE) because of the altered haemostatic balance, in particular an increase in thrombin generation. In patients with cirrhosis, vitamin K antagonists (VKA) and low molecular weight heparins (LMWH) are currently the standard of care for VTE prevention, with VKA also being standard of care for stroke prevention in those with atrial fibrillation. However, direct oral anticoagulants (DOAC) could have specific advantages in this patient population. Clinical experience suggests that DOAC are a safe and possibly more effective alternative to traditional anticoagulants for the treatment of VTE in patients with compensated cirrhosis. In addition, emerging data suggest that primary prophylactic treatment with anticoagulants may improve clinical outcomes in patients with cirrhosis by reducing the risk of hepatic decompensation. The selection of the most appropriate DOAC remains to be clarified. This review focuses on the rationale for the use of DOAC in patients with cirrhosis, the specific effects of the different DOAC (as assessed by in vitro and in vivo pharmacokinetic and pharmacodynamic studies), as well as clinical outcomes in patients with cirrhosis on DOAC.

Clot lysis time and thrombin generation in patients undergoing transcatheter aortic valve implantation.

BACKGROUND: Aortic valve stenosis (AS) is the most prevalent valvular heart disease and is associated with a significant increase in mortality. AS has been shown to be linked with numerous coagulation system abnormalities, including increased fibrin deposition on the stenotic aortic valves. Transcatheter aortic valve implantation (TAVI) is the primary treatment method for patients at high surgical risk. OBJECTIVES: The aim of the study was to assess the impact of treating severe AS with TAVI on thrombin generation and clot lysis time (CLT). METHODS: We studied 135 symptomatic AS patients recommended for TAVI by the local Heart Team. All measurements were performed before and 5-7 days after TAVI. Alongside clinical assessment and echocardiographic analysis, we assessed clot lysis time (CLT) and thrombin generation parameters, including lag time, peak thrombin generation, time to peak thrombin generation (ttPeak), and endogenous thrombin potential (ETP). RESULTS: 70 patients were included in the final analysis. After TAVI, there was a significant 9% reduction in CLT despite a 12% increase in fibrinogen concentration. We observed significant increase in lag time and ttPeak (20% and 12%, respectively), and 13% decrease in peak thrombin concentration compared to pre-procedural levels. Multivariable linear regression analysis demonstrated that baseline CLT and C-reactive protein (CRP) levels were independent predictors of significant reduction in mean aortic gradient, defined as TAVI procedure success. CONCLUSIONS: CLT and peak thrombin concentration decreased, while Lag time and ttPeak increased significantly after TAVI. Multivariable linear regression analysis demonstrated CLT and CRP levels as independent predictors of achieving a reduction in mean aortic gradient, defining TAVI procedure success.

Comprehensive laboratory assessment of lonoctocog alfa versus octocog alfa in severe haemophilia A.

INTRODUCTION: Lonoctocog alfa is a single-chain factor VIII (FVIII) molecule with high binding affinity to von-Willebrand-factor. While it is well known that its plasma activity is underestimated by one-stage clotting assays (OSCA), there is a lack of knowledge on the post-infusion performance of lonoctocog alfa in global coagulation assays or its potential impact on the haemostatic balance in vivo. AIM: To characterize lonoctocog alfa versus octocog alfa in pre- and post-infusion samples obtained from patients undergoing repeated investigation of incremental recovery (IR). METHODS: Eighteen patients with severe haemophilia A (lonoctocog alfa: 10, octocog alfa: 8) were included. A panel of factor-specific and global coagulation assays was applied, comprising a FVIII OSCA, two FVIII chromogenic substrate assays (CSA), rotational thrombelastography and thrombin generation (TG). Potential activation of coagulation was assessed by measuring plasma thrombin markers and levels of activated protein C. RESULTS: Comparable IRs were found for lonoctocog alfa and octocog alfa (2.36 [IU/dL]/[IU/kg] vs. 2.55 [IU/dL]/[IU/kg], respectively). Lonoctocog alfa activities were found to be underestimated by the FVIII OSCA while also the two FVIII CSAs showed statistically significant assay discrepancies on lonoctocog alfa. Effects of both FVIII products on rotational thrombelastography were less distinct than those on TG parameters. No elevated pre- or significantly shifting post-infusion plasma levels of coagulation biomarkers were detected. CONCLUSION: Lonoctocog alfa and octocog alfa showed comparable recovery and safety in vivo as well as similar impacts on TG in vitro. Observed assay discrepancies on lonoctocog alfa demonstrated variability of results also between different FVIII CSAs.

Predelivery Haemostatic Biomarkers in Women with Non-Severe Postpartum Haemorrhage.

Background: Postpartum haemorrhage (PPH) is a frequent complication of childbirth that is difficult to predict. Predelivery coagulation biomarkers may help to guide preventive strategies. Our objective was to evaluate the association of predelivery haemostatic biomarkers with non-severe PPH. Methods: A nested case-control study was conducted within the « Study of Biological Determinants of Bleeding Postpartum ¼ in order to compare different haemostatic biomarkers in plasma from pregnant women with non-severe PPH (cases) and controls without PPH matched for age, body mass index, term, and mode of delivery. Blood was collected at entry in the delivery room. Global haemostatic assays (thrombin generation assay (TGA) and plasmin generation assay (PGA)) were then performed on freshly thawed aliquots of platelet-poor plasma. Results: A total of 370 pregnant women (185 cases and 185 controls) were included. Median [interquartile range] predelivery platelet count was lower in PPH cases than in controls (217 [181-259] versus 242 [196-280] G/L). TGA and PGA parameters were similar between cases and controls. In a subset analysis of vaginal deliveries (n = 144), median predelivery TGA thrombin peak was lower, and median predelivery PGA lag phase was longer in cases compared to controls. In multivariable analysis, only predelivery platelet count was independently associated with non-severe PPH. Conclusions: Predelivery platelet count is associated with non-severe PPH. Differences in other haemostatic parameters are tenuous, questioning their usefulness in predicting non-severe PPH.

Elevated plasma factor XI is associated with postthrombotic syndrome.

INTRODUCTION: Postthrombotic syndrome (PTS), a common complication of deep vein thrombosis (DVT), is largely inflammatory by nature with contribution of prothrombotic mechanisms. The role of factor (F)XI in PTS has not been explored yet. We investigated whether elevated FXI is associated with PTS occurrence. MATERIALS AND METHODS: We enrolled 180 consecutive patients (aged 43 ± 13 years) with first-ever DVT. After 3 months FXI levels were measured, along with inflammatory markers, thrombin generation, plasma clot permeability (Ks), clot lysis time (CLT), and fibrinolysis proteins. We assessed PTS using the Villalta score and recorded symptomatic venous thromboembolism (VTE) at a 1-year and venous ulcers at a median 53 months follow-up. RESULTS: Baseline median FXI was 102 % [IQR 92-113 %] and showed positive association with Villalta score (R = 0.474, P < 0.001). Patients with PTS (n = 48, 26.7 %) had 16.1 % higher FXI (P < 0.001) and FXI ≥120 % occurred more often in PTS patients (odds ratio [OR] 5.55, 95 % confidence interval [CI] 2.28-13.47). There were associations of baseline FXI with Ks and CLT along with thrombin activatable fibrinolysis inhibitor (TAFI) activity, C-reactive protein, and interleukin-6, but not with fibrinogen, or thrombin generation. After age adjustment higher FXI was independently associated with PTS occurrence (OR per 1 % 1.06, 95 % CI 1.02-1.09) and VTE recurrence (OR 1.03, 95 % CI 1.01-1.06). At long-term follow-up, patients with venous ulcers had 13.6 % higher baseline FXI (P = 0.002). CONCLUSIONS: Elevated FXI in association with inflammation and prothrombotic fibrin clot properties may contribute to the development of PTS following DVT.

Global Hemostatic Methods to Tailor Treatment With Bypassing Agents in Hemophilia A With Inhibitors- A Single-Center, Pilot Study.

For patients with hemophilia A and high-titer inhibitors treated with bypassing agents there are no reliable methods to assess treatment effect. We investigated the utility of global hemostatic methods in assessing treatment with bypassing agents (rFVIIa or activated prothrombin complex [aPCC]). All patients with hemophilia A and inhibitors followed at the Coagulation Unit or the Pediatric Coagulation Unit at Karolinska University Hospital aged 6 years and above were eligible for this noninterventional study. Baseline plasma samples were spiked with bypassing agents in increasing concentrations (aPCC 50 U/kg, 100 U/kg, 150 U/kg, and rFVIIa 90 µg/kg and 270 µg/kg) in vitro. For patients treated with factor concentrates or bypassing agents follow-up samples were collected (in vivo tests). The samples were analyzed using overall hemostatic potential (OHP), and calibrated automated thrombogram, Calibrated Automated Thrombogram (CAT). Nine patients with hemophilia A with inhibitors were included. Spiking with rFVIIa normalized the coagulation potential in 6/8 samples, in 3 only with high dose. Only one sample did not improve adequately after spiking with aPCC. The improvement in hemostasis was reliably shown by both CAT and OHP. The baseline potential was, however, more often measurable by OHP compared to CAT. Factor concentrate had been administered to 5 patients normalizing the hemostatic potential in vivo in 2 (without spiking). The hemostatic improvement induced by spiking with rFVIIa or aPCC is shown by OHP and CAT, but the results have to be evaluated in larger cohorts.

A small-molecule hemostatic agent for the reversal of direct oral anticoagulant-induced bleeding.

Background: The bleeding risk associated with direct oral anticoagulants (DOACs) remains a major concern, and rapid reversal of anticoagulant activity may be required. Although specific and nonspecific hemostatic biotherapies are available, there is a need for small-molecule DOAC reversal agents that are simple and cost-effective to produce, store, and administer. Objectives: To identify and characterize a small molecule with procoagulant activity as a DOAC reversal agent. Methods: We sought to identify a small procoagulant molecule by screening a chemical library with a plasma clotting assay. The selected molecule was assessed for its procoagulant properties and its ability to reverse the effects of the DOACs in a thrombin generation assay. Its activity as a DOAC reversal agent was also evaluated in a tail-clip bleeding assay in mice. Results: The hemostatic molecule (HeMo) dose-dependently promoted thrombin generation in plasma, with dose values effective in producing half-maximum response ranging between 3 and 5 µM, depending on the thrombin generation assay parameter considered. HeMo also restored impaired thrombin generation in DOAC-spiked plasma and reversed DOAC activity in the mouse bleeding model. HeMo significantly reduced apixaban-induced bleeding from 709 to 65 µL (vs 43 µL in controls; P < .01) and dabigatran-induced bleeding from 989 to 155 µL (vs 126 µL in controls; P < .01). Conclusion: HeMo is a small-molecule procoagulant that can counterbalance hemostatic disruption by a thrombin inhibitor (dabigatran) or factor Xa inhibitors (apixaban and rivaroxaban). The compound's effective clot formation and versatility make it a possible option for managing the inherent hemorrhagic risk during DOAC therapy.

Comparative analysis of thrombin generation platforms for patients with coagulation factor deficiencies: A comprehensive assessment.

INTRODUCTION: Thrombin generation assays (TGAs) assess the overall functionality of the hemostatic system and thereby provide a reflection of the hemostatic capacity of patients with disorders in this system. Currently, four (semi-)automated TGA platforms are available: the Calibrated Automated Thrombogram, Nijmegen Hemostasis Assay, ST Genesia and Ceveron s100. In this study, we compared their performance for detecting patients with congenital single coagulation factor deficiencies. MATERIALS AND METHODS: Pooled patient samples, healthy control samples and normal pooled plasma were tested on all four platforms, using the available reagents that vary in tissue factor and phospholipid concentrations. The TGA parameters selected for analysis were peak height and thrombin potential. Results were normalized by using the calculated mean of healthy controls and a correction for between-run variation. Outcomes were presented as relative values, with the mean of healthy controls standardized to 100 %. RESULTS: Across all platforms and reagents used, thrombin potentials and peak heights of samples with coagulation factor deficiencies were lower than those of healthy controls. Reagents designed for bleeding tendencies yielded the lowest values on all platforms (relative median peak height 19-32 %, relative median thrombin potential 19-45 %). Samples representing more severe coagulation factor deficiencies generally exhibited lower relative peak heights and thrombin potentials. CONCLUSIONS: Thrombin generation assays prove effective in differentiating single coagulation factor deficient samples from healthy controls, with modest discrepancies observed between the platforms. Reagents designed for assessing bleeding tendencies, featuring the lowest tissue factor and phospholipid concentrations, emerged as the most suitable option for detecting coagulation factor deficiencies.