No effect of tranexamic acid on platelet function and thrombin generation (ETAPlaT) in postpartum haemorrhage: a randomised placebo-controlled trial

Efficacy and safety of tranexamic acid in prevention of postpartum hemorrhage: a systematic review and meta-analysis of 18,649 patients

BACKGROUND

In this meta-analysis, we aimed to update the clinical evidence regarding the efficacy and safety of TXA in the prevention of PPH.

METHODS

A literature search of PubMed, Scopus, Web of Science, Google Scholar, and Cochrane Library from inception until December 2022 was conducted. We included randomized controlled trials (RCTs) comparing TXA with a placebo among pregnant women. All relevant outcomes, such as total blood loss, the occurrence of nausea and/or vomiting, and changes in hemoglobin, were combined as odds ratios (OR) or mean differences (MD) in the meta-analysis models using STATA 17 MP.

RESULTS

We included 59 RCTs (18,649 patients) in this meta-analysis. For cesarean birth, TXA was favored over the placebo in reducing total blood loss (MD= -2.11 mL, 95%CI [-3.09 to -1.14], P < 0.001), and occurrence of nausea or/and vomiting (OR = 1.36, 95%CI [1.07 to 1.74], P = 0.01). For vaginal birth, the prophylactic use of TXA was associated with lower total blood loss, and higher occurrence of nausea and/or vomiting (MD= -0.89 mL, 95%CI [-1.47 to -0.31], OR = 2.36, 95%CI [1.32 to 4.21], P = 0.02), respectively. However, there were no differences between the groups in changes in hemoglobin during vaginal birth (MD = 0.20 g/dl, 95%CI [-0.07 to 0.48], P = 0.15). The overall risk of bias among the included studies varies from low to high risk of bias using ROB-II tool for RCTs.

CONCLUSIONS

This meta-analysis suggested that TXA administration is effective among women undergoing cesarean birth or vaginal birth in lowering total blood loss and limiting the occurrence of PPH. Further clinical trials are recommended to test its efficacy on high-risk populations.

Women with severe postpartum hemorrhage have a decreased endogenous thrombin potential before delivery

BACKGROUND

Severe postpartum hemorrhage (PPH), defined as a blood loss ≥1000 mL, is associated with maternal morbidity and mortality.

OBJECTIVES

We aimed at characterizing coagulation properties of predelivery plasmas from pregnant women with thrombin generation assay and hemostatic biomarkers (plasminogen activator inhibitor-1, tissue factor [TF], and thrombomodulin).

METHODS

A nested case-control study was conducted within the "Study of Biological Determinants of Bleeding Postpartum," a French prospective cohort study, in order to compare women with severe PPH (cases) and controls matched for age, body mass index, term, and mode of delivery. Plasma was collected at entry in the delivery room, and blood loss was measured objectively. The predelivery endogenous thrombin generation potential (ETP) was measured in plasma using calibrated automated thrombinography and low TF concentration. Hemostatic biomarkers were measured using ELISA kits.

RESULTS

A total of 142 women (71 cases and 71 controls) were investigated. There was no difference in the median lag phase, thrombin peak, and time to peak between cases and controls. However, median predelivery ETP was lower in cases than in controls (2170 vs 2408 nM.min, P < .0001), independently of mode of delivery and PPH etiology. Median plasminogen activator inhibitor-1 and TF levels were higher in cases compared with controls (107.4 vs 68.1 ng/mL, P = .0003; 34.4 vs 27.4 pg/mL, P = .007), whereas thrombomodulin levels did not differ between the 2 groups.

CONCLUSION

Among thrombin generation assay parameters, predelivery ETP levels may have a predictive value for severe PPH.

Evaluating the hemostatic effects of tranexamic acid in women with pre-eclampsia

OBJECTIVE

To evaluate the hemostatic effects of tranexamic acid (TXA) ex vivo in women with pre-eclampsia.

METHODS

This was an ex vivo study involving 45 normal pregnant women and 45 women with pre-eclampsia (nine with mild and 36 with severe features) matched for age, gestational age, and body mass index. Blood samples were collected and divided into two parts. The first served as the pre-TXA sample, while the second was spiked with TXA and served as the post-TXA sample. Plasma levels of D-dimer and plasmin-antiplasmin complex (PAP) were determined using enzyme-linked immunosorbent assay.

RESULTS

The mean D-dimer and PAP values in the pre-TXA samples differed significantly between groups. Following spiking with TXA, the mean D-dimer and PAP levels did not differ significantly in the pre-TXA and post-TXA samples (P = 0.560 and P = 0.500, respectively) in the pre-eclampsia cohort. In normal pregnancy, the mean D-dimer and PAP levels in the post-TXA samples did not differ significantly (P = 0.070 and P = 0.050, respectively) from the pre-TXA samples following TXA spiking.

CONCLUSION

TXA did not significantly affect D-dimer and PAP levels in pre-eclampsia, suggesting that TXA may not increase the thrombotic risks in patients with pre-eclampsia.

Haemostatic effect of adding tranexamic acid to emicizumab prophylaxis in severe haemophilia A: A preclinical study

BACKGROUND

Patients with severe haemophilia have impaired haemostatic response, delayed clot formation and fibrin clots that are vulnerable to fibrinolysis. Emicizumab is a bispecific antibody that mimics activity of activated factor VIII (FVIII) and increases haemostatic capacity to the level of moderate-to-mild haemophilia, thereby used for prophylaxis. Regardless of the impressive clinical performance of emicizumab, breakthrough bleeds may still occur. We aimed to study, in FVIII knockout mice (FVIII-KO), whether haemostasis is improved with the addition of tranexamic acid (TxAc) to emicizumab.

METHODS

FVIII-KO mice received prophylaxis with emicizumab or emicizumab+TxAc before trauma. FVIII-KO mice were given emicizumab 1.5 mg/kg via IV injection. A second retro-orbital IV injection containing human FIX and FX (both 100U/kg) was given 24 h later and 5 min before the tail amputation or knee trauma. After trauma-induced knee joint bleeding, magnetic resonance imaging (MRI), and histological analysis were used to compare haemostatic efficacy of the two prophylactic strategies. Thrombin generation (TG) was measured and clots obtained with TG experiment were analysed by scanning electron microscopy.

RESULTS

In FVIII-KO mice, blood loss after tail clip was lower after prophylaxis with emicizumab+TxAc compared to emicizumab. MRI results and histological analysis of knee joints showed that the addition of TxAc significantly decreased joint bleeding. Fibrin fibre diameters of mice treated with emicizumab only was thicker than those who received combined prophylaxis with emicizumab+TxAc.

CONCLUSION

Our results suggest a potential benefit of TxAc when used in combination with emicizumab in prophylactic settings, especially in patients presenting breakthrough bleeds.

Outcomes in Antiplatelet-Associated Intracerebral Hemorrhage in the TICH-2 Randomized Controlled Trial

Background

Antiplatelet therapy increases the risk of hematoma expansion in intracerebral hemorrhage (ICH) while the effect on functional outcome is uncertain.

Methods and Results

This is an exploratory analysis of the TICH‐2 (Tranexamic Acid in Intracerebral Hemorrhage‐2) double‐blind, randomized, placebo‐controlled trial, which studied the efficacy of tranexamic acid in patients with spontaneous ICH within 8 hours of onset. Multivariable logistic regression and ordinal regression were performed to explore the relationship between pre‐ICH antiplatelet therapy, and 24‐hour hematoma expansion and day 90 modified Rankin Scale score, as well as the effect of tranexamic acid. Of 2325 patients, 611 (26.3%) had pre‐ICH antiplatelet therapy. They were older (mean age, 75.7 versus 66.5 years), more likely to have ischemic heart disease (25.4% versus 2.7%), ischemic stroke (36.2% versus 6.3%), intraventricular hemorrhage (40.2% versus 27.5%), and larger baseline hematoma volume (mean, 28.1 versus 22.6 mL) than the no‐antiplatelet group. Pre‐ICH antiplatelet therapy was associated with a significantly increased risk of hematoma expansion (adjusted odds ratio [OR], 1.28; 95% CI, 1.01–1.63), a shift toward unfavorable outcome in modified Rankin Scale (adjusted common OR, 1.58; 95% CI, 1.32–1.91) and a higher risk of death at day 90 (adjusted OR, 1.63; 95% CI, 1.25–2.11). Tranexamic acid reduced the risk of hematoma expansion in the overall patients with ICH (adjusted OR, 0.76; 95% CI, 0.62–0.93) and antiplatelet subgroup (adjusted OR, 0.61; 95% CI, 0.41–0.91) with no significant interaction between pre‐ICH antiplatelet therapy and tranexamic acid (P interaction=0.248).

Conclusions

Antiplatelet therapy is independently associated with hematoma expansion and unfavorable functional outcome. Tranexamic acid reduced hematoma expansion regardless of prior antiplatelet therapy use.

Registration

URL: https://www.isrctn.com; Unique identifier: ISRCTN93732214.

Thrombin generation abnormalities in Quebec platelet disorder

INTRODUCTION

Calibrated automated thrombograms (CAT) with platelet-poor (PPP) and platelet-rich plasma (PRP) have provided useful insights on bleeding disorders. We used CAT to assess thrombin generation (TG) in Quebec platelet disorder (QPD)-a bleeding disorder caused by a PLAU duplication mutation that increases platelet (but not plasma) urokinase plasminogen activator (uPA), leading to intraplatelet (but not systemic) plasmin generation that degrades α-granule proteins and causes platelet (but not plasma) factor V (FV) deficiency.

METHODS

Calibrated automated thrombograms was used to test QPD (n = 7) and control (n = 22) PPP and PRP, with or without added tranexamic acid (TXA). TG endpoints were evaluated for relationships to platelet FV and uPA, plasma FV and tissue factor pathway inhibitor (TFPI) levels, and bleeding scores.

RESULTS

Quebec platelet disorder PPP TG was normal whereas QPD PRP had reduced endogenous thrombin potential and peak thrombin concentrations (P values < .01), proportionate to the platelet FV deficiency (R²  ≥ 0.81), but unrelated to platelet uPA, plasma FV, or bleeding scores. QPD TG abnormalities were not associated with TFPI abnormalities and were not reproduced by adding uPA to control PRP. TXA increased QPD and control PRP TG more than PPP TG, but it did not fully correct QPD PRP TG abnormalities or improve TG by plasminogen-deficient plasma.

CONCLUSION

Quebec platelet disorder results in a platelet-specific TG defect, proportionate to the loss of platelet FV, that is improved but not fully corrected by TXA. Our study provides an interesting example of why it is important to assess both PRP and PPP TG in bleeding disorders.

Tranexamic acid is effective in decreasing postoperative intraarticular bleeding in arthroscopic knee surgery

: Arthroscopic knee surgery to perform partial meniscectomy and anterior cruciate ligament (ACL) reconstruction is frequent and effective, although a possible complication is postoperative hemarthrosis. When intraarticular bleeding occurs, in addition to the associated pain, the patient usually requires joint aspiration (arthrocentesis) to avoid loss of range of motion (ROM). Sometimes this complication ends up associated with a poor result of surgery due to a loss of ROM. The aim of this narrative review of the literature is to attempt to clarify whether tranexamic acid (TXA) should be utilized in arthroscopic ACL reconstruction and arthroscopic meniscectomy and by what route (intraarticular or intravenous). A number of studies seem to favor the use of intravenous TXA in patients undergoing ACL reconstruction and arthroscopic synovectomy to diminish articular postoperative bleeding and its consequences (pain, swelling, loss of ROM, and the need for arthrocentesis). Regarding the use of intraarticular TXA, one in-vitro study has indicated that TXA in high concentrations is cytotoxic to chondrocytes. Common sense leads me to conclude that until better designed studies can confirm that intraarticular TXA is not cytotoxic to chondrocytes, its use should not be advised. Currently, for patients undergoing arthroscopic ACL reconstruction and arthroscopic meniscectomy, it seems safer to use intravenous TXA.

Hypofibrinolysis induced by tranexamic acid does not influence inflammation and mortality in a polymicrobial sepsis model

The biological relevance of fibrinolysis to the host response to sepsis is illustrated by pathogens such as S. pyogenes and Y. pestis, whose virulence factors are proteins that challenge the balance between pro- and anti-fibrinolytic factors of the host, and by the consistent finding of hypofibrinolysis in the early stages of sepsis. Whether this hypofibrinolytic response is beneficial or detrimental to the host, by containing the spread of pathogens while at the same time limiting the access of immune cell to infectious foci, is still a matter of debate. Tranexamic acid (TnxAc) is an antifibrinolytic agent that is being increasingly used to prevent and control bleeding in conditions such as elective orthopedic surgery, trauma, and post-partum-hemorrhage, which are frequently followed by infection and sepsis. Here we used a model of polymicrobial sepsis to evaluate whether hypofibrinolysis induced by TnxAc influenced survival, tissue injury and pathogen spread. Mice were treated with two doses of TnxAc bid for 48h, and then sepsis was induced by cecal ligation and puncture. Despite the induction of hypofibrinolysis by TnxAc, no difference could be observed in survival, tissue injury (measured by biochemical and histological parameters), cytokine levels or pathogen spread. Our results contribute with a new piece of data to the understanding of the complex interplay between fibrinolysis and innate immunity. While our results do not support the use of TnxAc in sepsis, they also address the thrombotic safety of TnxAc, a low cost and widely used agent to prevent bleeding.