How We Interpret Thrombosis with Thrombocytopenia Syndrome?

Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low platelet counts are referred to as thrombosis with thrombocytopenia syndrome, including heparin-induced thrombocytopenia, vaccine-induced immune thrombotic thrombocytopenia, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, thrombotic microangiopathy (TMA), and disseminated intravascular coagulation. TMA includes thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (HUS), and atypical HUS. Patients with these pathologies present with thrombosis and consumptive thrombocytopenia associated with the activation of platelets and the coagulation system. Treatment varies from disease to disease, and many diseases have direct impacts on mortality and organ prognosis if therapeutic interventions are not promptly implemented. Underlying diseases and the results of physical examinations and general laboratory tests as part of a thorough workup for patients should promptly lead to therapeutic intervention before definitive diagnosis. For some diseases, the diagnosis and initial treatment must proceed in parallel. Utilization of not only laboratory tests but also various scoring systems is important for validating therapeutic interventions based on clinical information.

Amyloid deposition through endocytosis in vascular endothelial cells.

No mechanistic lead is known for establishing AL amyloid deposits in organs. We here report an electron microscopic (EM) analysis in a case of intestinal AL amyloidosis before initiating treatment for amyloidosis. The dense deposits of amyloid fibrils are concentrated around the small blood vessels in the submucosal area of intestinal tissue. Surprisingly, we observed endothelial cells (ECs) of blood vessels containing plenty of endocytotic (pinocytotic) and transcytotic vesicles at the luminal side and above the basement membrane, indicating the one-way active trafficking of either the immunoglobulin (Ig) light chain or preassembled amyloid fibrils from the luminal side of ECs to the extraluminal area of ECs. Immunoelectron microscopy displayed that the immuno-gold signals were observed in the vascular cavity and the subendothelial area of amyloid deposits. However, there is no sign of an Ig light chain in pinocytotic vesicles. Therefore, the intestinal ECs may actively pump out mainly the preassembled amyloid fibrils (not light chains) from the blood stream into the subendothelial area as a physiologic function.

Idarucizumab for Emergency Reversal of the Anticoagulant Effects of Dabigatran: Final Results of a Japanese Postmarketing Surveillance Study.

INTRODUCTION: Idarucizumab, a monoclonal antibody fragment that rapidly reverses the anticoagulant effects of dabigatran, was approved in Japan in September 2016, at which time an all-case, postmarketing surveillance (PMS) study was initiated to collect data on idarucizumab in Japanese patients. Interim results were published previously, and the final results are reported herein. METHODS: This multicenter, open-label, uncontrolled, non-interventional PMS study was conducted in Japanese patients who received idarucizumab at the approved dose (2 × 2.5 g/50 ml) and had uncontrolled bleeding (group A) or required an emergency procedure (group B). The primary endpoint was the frequency of adverse drug reactions (ADRs). The secondary endpoint was the maximum extent of reversal of the anticoagulant effects of dabigatran, within 4 h of idarucizumab administration, based on activated partial thromboplastin time (aPTT). RESULTS: The final analysis included 804 patients. ADRs during the idarucizumab treatment and post-treatment periods were reported in 17 of 542 patients (3.1%) in group A and 12 of 240 patients (5.0%) in group B. Thrombotic events were reported in 22 patients (4.1%) in group A and 15 patients (6.3%) in group B, and hypersensitivity occurred in four (0.7%) and five patients (2.1%), respectively. Among 793 patients evaluated for effectiveness, 78 in group A and 26 in group B had aPTT data at baseline (immediately before idarucizumab administration) and within 4 h of idarucizumab administration; in these patients, median maximum percentage reversal within 4 h of idarucizumab administration was 100%. CONCLUSIONS: The final analysis from the PMS study confirms previous findings suggesting that idarucizumab can safely and effectively reverse the anticoagulant effects of dabigatran in Japanese patients in clinical practice. The results support the continued use of idarucizumab in Japan. TRIAL REGISTRATION: This study is registered with ClinicalTrials.gov (NCT02946931).

Atrial fibrillation is an irregular heart rhythm (arrhythmia), and the type of atrial fibrillation not caused by a heart valve problem is known as "non-valvular atrial fibrillation" or NVAF. People with NVAF have an increased risk of ischemic stroke, in which a blood clot (thrombus) blocks an artery in the brain. Drugs that inhibit blood clots, known as anticoagulants, are prescribed to people with NVAF to prevent ischemic stroke. Historically, warfarin has been one of the most prescribed anticoagulant drugs. However, a novel anticoagulant drug, known as dabigatran, has clinical advantages over warfarin and is approved in many countries for people with NVAF. People who take anticoagulants may experience life-threatening bleeding or need urgent surgery, and thus rapid and effective reversal of the anticoagulant effects is critical. The drug idarucizumab specifically binds to dabigatran to reverse its anticoagulant effects in people with uncontrolled bleeding or who require an urgent procedure. Idarucizumab was approved for use in Japan in September 2016. In Japan, drug companies are obligated to collect data after a new drug is launched as an approval condition, which is done through a postmarketing surveillance study. Here, we report the final results of a postmarketing surveillance study conducted between September 2016 and November 2020 to evaluate the safety and effectiveness of idarucizumab in Japanese patients receiving dabigatran. The results of our study show that idarucizumab can safely and effectively reverse the anticoagulant effects of dabigatran in Japanese patients, and support the continued use of idarucizumab in Japan in clinical practice.

Distinguishing immune-mediated thrombotic thrombocytopenic purpura from septic disseminated intravascular coagulation using plasma levels of haptoglobin and factor XIII activity.

Background: Both immune-mediated thrombotic thrombocytopenic purpura (iTTP) and septic disseminated intravascular coagulation (DIC) are life-threatening disorders developed by platelet-consuming microvascular thrombi and necessitate immediate therapeutic interventions. Although severe deficiencies of plasma haptoglobin in iTTP and factor XIII (FXIII) activity in septic DIC have been reported, few studies have focused on the possibility of using these markers to distinguish between iTTP and septic DIC. Objectives: We investigated whether the plasma levels of haptoglobin and FXIII activity could be helpful for differential diagnosis. Methods: Thirty-five patients with iTTP and 30 with septic DIC were enrolled in the study. Patient characteristics, coagulation, and fibrinolytic markers were collected from the clinical data. Plasma haptoglobin and FXIII activities were measured using chromogenic Enzyme-Linked Immuno Sorbent Assay and an automated instrument, respectively. Results: The median plasma haptoglobin level was 0.39 mg/dL and 54.20 mg/dL in the iTTP and septic DIC groups, respectively. The median plasma FXIII activities were 91.3% and 36.3% in the iTTP and septic DIC groups, respectively. In the receiver operating characteristic curve analysis, the cutoff level of plasma haptoglobin was 2.868 mg/dL and the area under the curve was 0.832. The cutoff level for plasma FXIII activity and the area under the curve were 76.0% and 0.931, respectively. The thrombotic thrombocytopenic purpura (TTP)/DIC index was defined by FXIII activity (percentage) and haptoglobin (milligrams per decilitre). Laboratory TTP was defined as an index ≥60 and laboratory DIC <60. The sensitivity and specificity of the TTP/DIC index were 94.3% and 86.7%, respectively. Conclusion: The TTP/DIC index, composed of plasma levels of haptoglobin and FXIII activity, is useful in differentiating iTTP from septic DIC.

Identification and Prognostication of End-of-Life State Using a Japanese Guideline-Based Diagnostic Method: A Diagnostic Accuracy Study.

Purpose: Prognostic uncertainty can be a barrier to providing palliative care. Accurate prognostic estimation for patients at the end of life is challenging. This study aimed to evaluate the accuracy of end-of-life diagnosis using our unique diagnostic method. Patients and Methods: A retrospective longitudinal observational study was conducted through collaboration among three medical facilities in a rural super-aged community in Japan. In 2007, we established a unique end-of-life diagnostic process comprising (1) physicians' judgement, (2) disclosure to patients, and (3) discussion at an end-of-life case conference (EOL-CC), based on Japanese end-of-life-related guidelines. Research subjects were consecutive patients discussed in EOL-CC between January 1, 2010, and September 30, 2017. The primary outcome was mortality within 6 months after the initial EOL-CC decision. Sensitivity, specificity, and diagnostic odds ratio were calculated using EOL-CC diagnosis (end-of-life or non-end-of-life) as an index test and overall survival (<6 months or ≥6 months) as a reference standard. Results: In total, 315 patients were eligible for survival analysis (median age 89, range 54-107). The study population was limited to patients with severe conditions such as advanced cancer, organ failures, advanced dementia with severe deterioration in functioning. EOL-diagnosis by our methods was associated with much lower survival rate at 6 months after EOL-CC than non-EOL-diagnosis (6.9% vs 43.5%; P < 0.001). Of the patients, 297 were eligible for diagnostic accuracy analysis (median age 89, range 54-107). The EOL-diagnosis showed high sensitivity (0.95; 95% confidence interval [CI] 0.92-0.97) but low specificity (0.35; 95% CI 0.20-0.53) against the outcomes. It also showed a high diagnostic odds ratio (10.32; 95% CI 4.08-26.13). Conclusion: The diagnostic process using the Japanese end-of-life guidelines had tolerable accuracy in identification and prognostication of end of life.

The efficacy and safety of caplacizumab in Japanese patients with immune-mediated thrombotic thrombocytopenic purpura: an open-label phase 2/3 study.

Caplacizumab is an anti-von Willebrand factor humanized single-variable-domain immunoglobulin fragment whose efficacy and safety in immune-mediated thrombotic thrombocytopenia purpura (iTTP) have been demonstrated in international studies. This prospective, open-label phase 2/3 study evaluated caplacizumab 10 mg administered daily during plasma exchange and for 30 days afterward, in combination with immunosuppressive treatment, in Japanese adults with a clinical diagnosis of iTTP (new or recurrent). The primary endpoint was prevention of iTTP recurrence; key secondary endpoints included time to platelet count response, time to organ damage normalization, and safety. Among 21 treated patients, 1 of 15 (6.7%) evaluable patients developed iTTP recurrence. Median time to normalization was 2.79 days for platelet count and 2.65 days for organ damage markers (n = 15). Treatment-emergent adverse events (TEAEs) were mostly mild to moderate in severity; the most frequently reported caplacizumab-related TEAEs were increased alanine aminotransferase, epistaxis, and gastrointestinal hemorrhage (all in 9.5% of patients). At least one bleeding event was reported in 7 of 21 patients (33%). Caplacizumab was effective in Japanese patients with iTTP, with a low rate of iTTP recurrence, rapid normalization of platelet counts and organ damage markers, and no unexpected TEAEs. Trial registration: ClinicalTrials.gov identifier, NCT04074187.

Effect of Anticoagulant/Antifibrinolytic Combination Therapy on Enhanced Fibrinolytic-Type Disseminated Intravascular Coagulation in End-of-Life Stage Solid Tumor Patients.

Thrombotic disorders such as venous thromboembolism and disseminated intravascular coagulation (DIC) are known complications of solid tumors. To date, no reports have described the treatment of enhanced fibrinolytic-type DIC caused by end-of-life stage solid tumors. We encountered three cases of end-of-life stage solid tumors complicated by enhanced fibrinolytic-type DIC with severe bleeding symptoms. In all three cases, bleeding symptoms improved dramatically after intervention for enhanced fibrinolytic-type DIC with heparin(s) and tranexamic acid. Improvements in abnormal coagulation test results were also seen and the need for platelet concentrate transfusion and fresh frozen plasma infusion was able to be eliminated. However, one patient developed multiple cerebral infarctions. In the future, further studies to investigate the need for intervention in enhanced fibrinolytic-type DIC caused by end-of-life stage solid tumors and suitable treatment strategies are warranted.

[Improving outcome of COVID-19-associated thrombosis: the need for evaluation of fibrinolytic activation].

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 and is known to have thrombotic complications. Various-sized thrombosis occurs in the arteries and veins, especially in lung tissue. The prevention and treatment of thrombosis is an important issue that is directly linked to its prognosis. Additionally, the drastic fibrinolytic enhancement and lethal bleeding in some severe COVID-19 are important issues. The efficacy of antiplatelet for COVID-19 is controversial. Thus, warfarin or tranexamic acid alone should be avoided. Heparin is effective for mild to moderate COVID-19 but is ineffective in severe cases since the anticoagulant activity of heparin is insufficient or heparin increases major bleeding. In severe COVID-19 cases with drastic fibrinolytic enhancement, heparin and nafamostat combination therapy may avoid lethal bleeding. In COVID-19 clinical practice, not only the coagulation activation was evaluated but also the fibrinolytic activation to consider treatment strategies.

Coagulopathy and Fibrinolytic Pathophysiology in COVID-19 and SARS-CoV-2 Vaccination.

Coronavirus Disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is frequently complicated by thrombosis. In some cases of severe COVID-19, fibrinolysis may be markedly enhanced within a few days, resulting in fatal bleeding. In the treatment of COVID-19, attention should be paid to both coagulation activation and fibrinolytic activation. Various thromboses are known to occur after vaccination with SARS-CoV-2 vaccines. Vaccine-induced immune thrombotic thrombocytopenia (VITT) can occur after adenovirus-vectored vaccination, and is characterized by the detection of anti-platelet factor 4 antibodies by enzyme-linked immunosorbent assay and thrombosis in unusual locations such as cerebral venous sinuses and visceral veins. Treatment comprises high-dose immunoglobulin, argatroban, and fondaparinux. Some VITT cases show marked decreases in fibrinogen and platelets and marked increases in D-dimer, suggesting the presence of enhanced-fibrinolytic-type disseminated intravascular coagulation with a high risk of bleeding. In the treatment of VITT, evaluation of both coagulation activation and fibrinolytic activation is important, adjusting treatments accordingly to improve outcomes.

Therapeutic Strategies for Disseminated Intravascular Coagulation Associated with Aortic Aneurysm.

Aortic aneurysms are sometimes associated with enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). In enhanced-fibrinolytic-type DIC, both coagulation and fibrinolysis are markedly activated. Typical cases show decreased platelet counts and fibrinogen levels, increased concentrations of fibrin/fibrinogen degradation products (FDP) and D-dimer, and increased FDP/D-dimer ratios. Thrombin-antithrombin complex or prothrombin fragment 1 + 2, as markers of coagulation activation, and plasmin-α2 plasmin inhibitor complex, a marker of fibrinolytic activation, are all markedly increased. Prolongation of prothrombin time (PT) is not so obvious, and the activated partial thromboplastin time (APTT) is rather shortened in some cases. As a result, DIC can be neither diagnosed nor excluded based on PT and APTT alone. Many of the factors involved in coagulation and fibrinolysis activation are serine proteases. Treatment of enhanced-fibrinolytic-type DIC requires consideration of how to control the function of these serine proteases. The cornerstone of DIC treatment is treatment of the underlying pathology. However, in some cases surgery is either not possible or exacerbates the DIC associated with aortic aneurysm. In such cases, pharmacotherapy becomes even more important. Unfractionated heparin, other heparins, synthetic protease inhibitors, recombinant thrombomodulin, and direct oral anticoagulants (DOACs) are agents that inhibit serine proteases, and all are effective against DIC. Inhibition of activated coagulation factors by anticoagulants is key to the treatment of DIC. Among them, DOACs can be taken orally and is useful for outpatient treatment. Combination therapy of heparin and nafamostat allows fine-adjustment of anticoagulant and antifibrinolytic effects. While warfarin is an anticoagulant, this agent is ineffective in the treatment of DIC because it inhibits the production of coagulation factors as substrates without inhibiting activated coagulation factors. In addition, monotherapy using tranexamic acid in cases of enhanced-fibrinolytic-type DIC may induce fatal thrombosis. If tranexamic acid is needed for DIC, combination with anticoagulant therapy is of critical importance.

Effect on Plasma Protein S Activity in Patients Receiving the Factor Xa Inhibitors.

AIMS: Measurement of protein S (PS) activity in patients taking direct oral anticoagulants (DOACs) using reagents based on a clotting assay results in falsely high PS activity, thus masking inherited PS deficiency, which is most frequently seen in the Japanese population. In this study, we investigated the effect of factor Xa (FXa) inhibitors on PS activity using the reagent on the basis of the chromogenic assay, which was recently developed in Japan. METHODS: The study enrolled 152 patients (82 males and 70 females; the average age: 68.5±14.0 years) receiving three FXa inhibitors (rivaroxaban, edoxaban, and apixaban). PS activity was measured using the reagents on the basis of the clotting and chromogenic assays. RESULTS: PS activity measured by the clotting assay reagents exhibited falsely high values depending on the plasma concentrations of FXa inhibitors in patients taking either rivaroxaban or edoxaban. However, none of the three FXa inhibitors affected PS activity when measured using the chromogenic assay. CONCLUSION: In patients taking rivaroxaban or edoxaban, inherited PS deficiency is likely missed because the levels of PS activity measured using the reagents based on the clotting assay are falsely high. However, we report that three FXa inhibitors do not affect PS activity measured by the chromogenic assay. When measuring the levels of PS activity in patients undergoing DOACs, the principles of each reagent should be understood. Furthermore, plasma samples must be collected at the time when plasma concentrations of DOACs are lowest or the DOAC-Stop reagent should be used.

Recombinant human erythropoietin attenuates hepatic dysfunction by suppressing hepatocellular apoptosis in lipopolysaccharide-induced disseminated intravascular coagulation in rats.

The aim of the present study was to clarify the effect of recombinant human erythropoietin (EPO) and low molecular weight heparin (LMWH) on a rat model of lipopolysaccharide (LPS)-induced disseminated intravascular coagulation (DIC). Experimental DIC was induced by sustained infusion of 5 mg/kg LPS for 4 h. EPO or LMWH was then administered to the LPS-induced DIC model. LPS-induced consumption coagulopathy, hemostatic activation and plasma TNF elevation remained unaltered in the LPS+EPO group, except for the D-dimer levels, and these abnormalities were significantly improved in the LPS+LMWH group. Plasma alanine aminotransferase (ALT) levels were markedly reduced in the LPS+EPO group, accompanied by a significant suppression of hepatocellular apoptosis. In the LPS+LMWH group, plasma creatinine levels and glomerular fibrin deposition were significantly attenuated, along with plasma ALT levels and hepatocellular apoptosis. Thus, a single administration of EPO may improve hepatic dysfunction by primarily exerting an anti-apoptotic, not anticoagulant, effect in the LPS-induced DIC model.

Blue Rubber Bleb Nevus Syndrome Complicated by Enhanced-Fibrinolytic-Type DIC: A Case Report.

A 54-year-old Japanese man was diagnosed with blue rubber bleb nevus syndrome (BRBNS) due to venodilation in the lower extremities at birth and gastrointestinal vascular malformations. He also had small bowel bleeding and enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). Endoscopic sclerotherapy for intestinal hemangioma could not be performed because of bleeding concerns; instead, a combined anticoagulant and antifibrinolytic treatment was performed. Although combination treatment with unfractionated heparin and tranexamic acid proved ineffective for small bowel bleeding, combination treatment with apixaban and tranexamic acid dramatically improved enhanced-fibrinolytic-type DIC. In BRBNS, treatment strategies should be considered after performing detailed coagulation tests.

Effect of NOS Inhibitors and Anticoagulants on Nitric Oxide Production in a Tissue-factor Induced Rat DIC Model.

BACKGROUND/AIM: We examined the mechanism of nitric oxide (NO) production in a tissue-factor (TF)-induced disseminated intravascular coagulation (DIC) model in rats, using inducible nitric oxide synthase (iNOS) inhibitor (L-NIL), endothelial nitric oxide synthase (eNOS) inhibitor (L-NAME), Factor Xa inhibitor (DX-9065a), and thrombin inhibitor argatroban. MATERIALS AND METHODS: Experimental DIC was induced by sustained infusion of 3.75 U/kg TF for 4 h via the tail vein. We then investigated the effect of these four agents on TF-induced DIC. RESULTS: Administration of L-NIL or L-NAME during induction of TF-induced DIC did not affect hemostatic markers, whereas elevated plasma levels of NO metabolites (NOX) were significantly suppressed by co-administration of L-NAME. A significant increase in eNOS-mRNA expression was observed in the TF-induced DIC model. Argatroban almost completely suppressed eNOS-mRNA expression. CONCLUSION: eNOS plays an important role in the NO production in the TF-induced DIC, and thrombin is a key stimulant of eNOS-mRNA expression in this model.

Evaluation of Optimal Sample Processing Conditions for Accurate Measurement of Protein S Activity.

OBJECTIVE: Protein S(PS) activity, especially PS-specific activity calculated by total PS activity (tPSAct) divided by total PS antigen (tPSAg), is important in the diagnosis of hereditary PS deficiency (PSD). The cleavage of PS at a thrombin-sensitive region (TSR) by proteases reduces the anticoagulant activity of PS. Therefore, we investigated the effect of sample processing and storage on tPSAct and PS cleavage. METHODS: Blood samples were collected from ten healthy subjects, and tPSAg and tPSAct were measured in whole blood or plasma stored at room temperature (RT) or 4°C. The cleaved PS was detected by western blotting, and the relationship between decreases in PS-specific activity and increase rates of cleaved PS was evaluated. Furthermore, the stability of tPSAg and tPSAct on the long-term storage of plasma was also evaluated. RESULTS: Both whole blood and plasma stored at RT and whole blood stored at 4°C showed decreased tPSAct (50-80%) after 24 hours (P<0.05). PS-specific activity levels negatively correlated with the increase rate of cleaved PS (r =-0.84, P<0.001). The tPSAct was decreased to 60% after three days in plasma stored at 4°C (P<0.05) but was stable for about one month when stored at -20°C or below. CONCLUSION: Inappropriate processing and storage result in falsely low PS-specific activity due to the cleavage of PS in the blood collection tubes, which may lead to misdiagnosis of PSD. Samples should be centrifuged immediately after collection, and the plasma should be frozen.