Research and Practice in Thrombosis and Haemostasis最新文献

Background

Our prior genome-wide association study of thrombin-induced platelet aggregation identified a G protein–coupled receptor kinase 5 (GRK5) noncoding variant (rs10886430-G) that is strongly associated with increased platelet reactivity to thrombin. This variant predisposes to increased risk of stroke, pulmonary embolism, and venous thromboembolism.

Objectives

To determine role of platelet specific GRK5 in platelet responses to agonists and injury.

Methods

Platelets from GRK5 mutant mice have been shown to have increased thrombin sensitivity, indicating that GRK5 may be a negative regulator of platelet activation. However, this has not been studied in a platelet-specific manner. We therefore used platelet-specific GRK5 mutant mice and models of thrombosis and pulmonary embolism.

Results

We now demonstrate that mice lacking GRK5 specifically in platelets had a mild increase in thrombin responses in vitro and a shortened time to arterial thrombosis in vivo. In addition, platelet GRK5 mutant mice had increased thrombin but not collagen-induced thrombus burden in a mouse model of pulmonary embolism.

Conclusion

These data indicate that platelet GRK5 has a significant role in limiting platelet responses to thrombin.

A State of the Art lecture titled “Syndemics in Women’s Health: Poverty, Social Exclusion and Clustering of Thrombotic and Haemostasis Disorders” was presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2023. Syndemics are characterized by the clustering of specific health conditions in vulnerable populations. These populations become vulnerable as a result of large-scale social, political, and economic factors that influence social determinants of health and increase susceptibility to disease. Vulnerable populations at risk of experiencing a syndemic include those who are subjected to social exclusion and gender- or race-based marginalization. Biological sex (assigned at birth based on physical & genetic differences) and gender identity (the personal sense of ones own gender) have been recognized as important determinants of health outcomes in the context of certain syndemic diseases. Potential examples of syndemic biosocial interactions in the field of thrombosis and hemostasis include the effect of social determinants of health in perpetuating the global maternal mortality crisis and the role of poverty and marginalization in influencing thrombosis risk in socially excluded individuals. Initiatives directed at prevention and treatment of syndemic conditions require multilevel interventions directed at the socio-economic as well as the biological determinants of the disease. In the present article, we describe potential syndemic disease interactions in the field of thrombosis and hemostasis, and we summarize some relevant new data relating to the social determinants of health presented during the 2023 ISTH Congress.

Background

Limited evidence exists regarding the incidence of recurrent venous thromboembolism (VTE) in patients diagnosed with isolated distal deep vein thrombosis (DVT) who are at risk of thrombosis extension whether they receive anticoagulation therapy or not.

Objectives

The study aimed to investigate the incidence of recurrent VTE and the impact of rivaroxaban in this patient population.

Methods

This open-label, exploratory, and randomized controlled trial was conducted at 7 centers in Japan between April 2019 and April 2022. Adult patients with isolated distal DVT at risk of thrombosis extension received either rivaroxaban combined with physical therapy or physical therapy alone for 90 days. Whole-leg ultrasound was performed at 14 and 90 days. We assessed a composite outcome of symptomatic or asymptomatic proximal DVT or symptomatic pulmonary embolism as the primary outcome until the end of the treatment period using an intention-to-treat analysis. Major bleeding was evaluated as a key secondary outcome.

Results

Out of 90 enrolled patients, 3 were excluded due to withdrawal of consent; therefore, we analyzed 87 participants. The rivaroxaban group (n = 42) reported no primary outcomes (0%; 95% CI, 0.0%-8.4%), whereas the physical therapy group (n = 45) had 2 cases of symptomatic proximal DVT (4.4%; 95% CI, 0.5%-15.1%). Major bleeding events occurred in 4 patients in the rivaroxaban group (9.5%; 95% CI, 2.7%-22.6%), whereas no events occurred in the physical therapy group (0%; 95% CI, 0%-7.9%).

Conclusion

Preliminary data suggest that rivaroxaban may reduce the risk of VTE recurrence among this patient subset, albeit with an increased incidence of bleeding events.

Postpartum hemorrhage (PPH) is an obstetric complication with high associated morbidity. Recombinant activated factor VII (rFVIIa) is used to treat severe PPH when uterotonics fail to stop bleeding. However, data on the safety of rFVIIa treatment of severe PPH from adequately powered trials are lacking. We systematically reviewed published data on the incidence of thromboembolic events (TEs) in women with PPH treated or not treated with rFVIIa (PROSPERO CRD42022360736). Databases (Embase, MEDLINE, BIOSIS, Current Contents, and the Cochrane Library) were searched for peer-reviewed publications published between January 1996 and August 2022 and conference abstracts published between January 2017 and August 2022 using search terms related to thromboembolism or infarction and PPH. Data were extracted from all publications reporting on a general population of women with PPH with information on TEs. Descriptive summary statistics and the estimated proportion of TEs were analyzed using a generalized linear mixed model based on the binomial distribution. Quality assessments were based on the checklist by Downs and Black. From 1637 potentially eligible studies, 55 publications were included reporting on 611 women treated and 32,488 women not treated with rFVIIa. The global estimated proportion of TEs was 1.82% (prediction interval [PI], 0.30-10.23) and 0.72% (PI, 0.03-16.47) in women with severe PPH treated and those not treated with rFVIIa, respectively. The estimated proportions of TEs were similarly small, with wide and largely overlapping PIs. Additional well-designed trials are needed to improve understanding of TE incidence in PPH.

Background

Chronic kidney disease (CKD) is associated with increased bleeding and thrombotic risks. Standard blood tests do not sufficiently quantify these risks. Global coagulation assays (GCAs) provide a more comprehensive assessment of coagulation.

Objectives

We aimed to evaluate if GCAs are predictive of spontaneous major bleeding (sMB) in CKD.

Methods

Adult patients with CKD (estimated glomerular filtration rate, <30 mL/min/1.73m²) were recruited to this pilot prospective observational study. Testing with GCAs (thromboelastography, overall hemostatic potential, calibrated automated thrombogram, and plasminogen activator inhibitor-1) was performed, and the results were correlated to sMB events.

Results

Eighty-seven CKD patients (median age, 67 years; 67.8% male) were included, with median follow-up of 3.1 years. CKD patients demonstrated elevated fibrinogen, factor VIII, and von Willebrand factor antigen levels, while other conventional coagulation test results were within reference intervals. Ten episodes of sMB (11.5%) were captured (3.0/100 person-years), with no significant association demonstrated between sMB and antiplatelet use (P = .36), platelet count (P = .14), or renal function (urea, P = .27; estimated glomerular filtration rate, P = .09). CKD patients with sMB had more hypocoagulable GCA parameters compared with those without sMB. The lowest quartiles of endogenous thrombin potential (subhazard ratio [sHR], 7.11; 95% CI, 1.84-27.45), overall hemostatic potential (sHR, 6.81; 95% CI, 1.77-26.16), and plasminogen activator inhibitor-1 (sHR, 5.26; 95% CI, 1.55-17.91) were associated with sMB.

Conclusion

This pilot study demonstrates that GCAs such as thrombin and fibrin generation may predict sMB risk in patients with CKD, which has potential to be practice-changing. Larger studies are required to validate these findings.

Background

Life-long vitamin K antagonist (VKA) therapy is recommended as a standard of care in antiphospholipid syndrome (APS) patients with thrombosis. Concerns have been raised about the validity of international normalized ratio (INR) measurements in lupus anticoagulant (LA)-positive APS patients because LA may interfere with phospholipid-dependent coagulation tests and could elevate INR measurements.

Objectives

Here, we aimed to determine the interference of antigen-specific monoclonal and isolated patient antibodies with LA activity on INR measurements.

Methods

Pooled normal plasma and control plasma from patients on VKA (without LA) were incubated with monoclonal and isolated patient immunoglobulin G antiprothrombin and anti–beta-2-glycoprotein I antibodies that express LA activity. INR was determined before and after addition using 3 laboratory assays (Owren STA-Hepato Prest, Quick STA-NeoPTimal, and Quick STA-Neoplastine R) and 1 point-of-care test device (CoaguChek Pro II).

Results

Antiprothrombin and anti–beta-2-glycoprotein I antibodies with LA activity interfered with recombinant human thromboplastin reagents (Quick STA-Neoplastine R and CoaguChek Pro II), particularly when added to plasma of VKA-treated controls. This effect was most evident on point-of-care test INR measurements, while the recombinant Quick reagent exhibited a lesser degree of interference. In contrast, tissue-derived thromboplastin reagents (Owren STA-Hepato Prest and Quick STA-NeoPTimal) remained largely unaffected by these antibodies, both in pooled normal plasma and VKA anticoagulated control plasma. Among these reagents, the Owren INR reagent exhibited the lowest sensitivity to the influence of LA antibodies. This observed difference in sensitivity is independent of the plasma dilution factor or the presence of factor V or fibrinogen in Owren reagent.

Conclusion

INR reagents that utilize recombinant human thromboplastin are more sensitive to the presence of monoclonal and patient-derived antibodies with LA activity. Consequently, APS patients positive for LA should be monitored using tissue-derived thromboplastin reagents, given its reduced susceptibility to interference by LA-causing antibodies.

Background

Real-world experience with efmoroctocog alfa (a recombinant factor [F]VIII Fc fusion protein [rFVIIIFc]) and eftrenonacog alfa (a recombinant factor IX Fc fusion protein [rFIXFc]) is needed to bridge evidence gaps.

Objectives

To describe rFVIIIFc/rFIXFc usage and effectiveness over a 24-month prospective period.

Methods

PREVENT (NCT03055611), a noninterventional study across 25 German hemophilia treatment centers, enrolled previously treated persons with hemophilia A and B (all ages/severities) on individualized rFVIIIFc/rFIXFc prophylaxis before/at enrollment. Primary endpoints included annualized bleeding rate (ABR), injection frequency (IF), and factor consumption (FC). Additionally, up to 12 months of retrospective FVIII/FIX data were collected. Physician and patient satisfaction, and safety outcomes were also assessed.

Results

Overall, 150 patients received ≥1 rFVIIIFc dose and 47 patients received ≥1 rFIXFc dose, with median prospective follow-up of 20.6 and 21.0 months, respectively. rFVIIIFc/rFIXFc demonstrated low median ABR (0.5/1.7), annualized IF (121.8/52.2 injections/y), and FC (4611.7/2423.9 IU/kg) in line with product labels. Compared with previous FVIII/FIX, there was a 56.0% reduction in ABR for rFVIIIFc (rate ratio, 0.44; 95% CI, 0.31-0.64), with no change for rFIXFc (rate ratio, 0.93; 95% CI, 0.66-1.31); rFVIIIFc/rFIXFc reduced annualized IF (rFVIIIFc, mean difference, −31.7; 95% CI, −40.3 to −23.1; rFIXFc, mean difference, −37.3; 95% CI, −46.9 to −27.8), while FC remained stable (rFVIIIFc, +374.1; 95% CI, +46.8 to +701.3; rFIXFc, +503.9; 95% CI, +95.4 to +912.4). Most physicians and patients were satisfied or highly satisfied with rFVIIIFc/rFIXFc. rFVIIIFc/rFIXFc were well tolerated, with no inhibitor development or treatment-related serious adverse events.

Conclusion

Real-world PREVENT data complement phase 3 trials and show that individualized rFVIIIFc/rFIXFc prophylaxis provided stable bleed protection with low IF and maintained FC. Compared with previous FVIII, ABR was considerably reduced with rFVIIIFc, with stable annualized FC. For rFIXFc, bleed protection was maintained vs previous FIX while reducing annualized IF.