Clotting of the Extracorporeal Circuit in Hemodialysis: Beyond Contact-Activated Coagulation.

Thrombotic complications in patients with end-stage kidney disease are frequent. While being a lifesaving treatment for these patients, hemodialysis introduces a thromboinflammatory environment. Additionally, the extracorporeal hemodialysis circuit itself is prone to clotting because of an interaction between different activation mechanisms of the coagulation system, platelets, and the immune system. Anticoagulation of the patient and the machine is frequently complicated by bleeding. We discuss the factors important in this balancing act and touch on potential strategies that are on the horizon to target thromboinflammation.

The 2023 Belgian clinical guidance on anticoagulation management in hospitalized and ambulatory COVID-19 patients.

COVID-19 is associated with an increased risk for thrombotic complications. The trials investigating the optimal thromboprophylactic dose are performed in challenging times and seemingly produce conflicting evidence. The burdensome circumstances, divergent endpoints, and different analytical approaches hamper comparison and extrapolation of available evidence. Most importantly, clinicians should provide thromboprophylaxis in hospitalized COVID-19 patients while (re)assessing bleeding and thrombotic risk frequently. The COVID-19 Thromboprophylaxis Working Group of the BSTH updated its guidance document. It aims to summarize the available evidence critically and to guide clinicians in providing the best possible thromboprophylaxis.

Emicizumab for acquired haemophilia A: A case series.

BACKGROUND: Emicizumab is approved to prevent bleeding in patients with congenital haemophilia A with or without inhibitors. However, no randomized trials addressed the efficacy of emicizumab in acquired haemophilia A (AHA). AIMS: To report the clinical and biochemical response of emicizumab in AHA. METHODS: This single-centre retrospective study included seven adults with AHA between November 2020 and May 2022. We collected patient characteristics, laboratory coagulation parameters, the use of haemostatic agents, bleeds and thrombotic events. Treatment was monitored using chromogenic FVIII assays. The assay with human reagents assesses both the emicizumab FVIII-like-activity and native patient FVIII-activity. The assay with bovine reagents only measures the patients' native FVIII-activity as emicizumab does not bind to bovine reagents. RESULTS: Patients presented with spontaneous hematoma (n = 7), intramuscular bleeding (n = 2), haematuria (n = 2) and/or gastro-intestinal bleeding (n = 2). Six patients had major bleedings. At diagnosis, APTT was prolonged (91 seconds, IQR 73-103), FVIII activity was 0% (IQR 0-1) and FVIII inhibitor 182 BU/mL (IQR 104-228). Emicizumab was administered weekly (3 mg/kg) for 4 weeks, and thereafter every 2 weeks until regression of the inhibitor. Three patients received activated FVIIa (cumulative dose of 1.7 mg/kg, IQR 1.2-2.2). All bleedings were controlled after treatment initiation, without further bleeds. After starting emicizumab, FVIII-like activity reached ≥5% at 12 days (IQR 7-14), whereas recovery of the intrinsic FVIII-activity ≥5% occurred at 128 days (IQR 88-173), coinciding with the disappearance of the FVIII inhibitor. There were no safety issues. CONCLUSION: In this AHA case series, no new clinically relevant bleeds were observed after initiation of emicizumab in conjunction with standard immunosuppressive therapy.

Risk of venous thromboembolic events after COVID-19 infection: a systematic review and meta-analysis.

Data regarding the occurrence of venous thromboembolic events (VTE), including acute pulmonary embolism (PE) and deep vein thrombosis (DVT) in recovered COVID-19 patients are scant. We performed a systematic review and meta-analysis to assess the risk of acute PE and DVT in COVID-19 recovered subject. Following the PRIMSA guidelines, we searched Medline and Scopus to locate all articles published up to September 1st, 2022, reporting the risk of acute PE and/or DVT in patients recovered from COVID-19 infection compared to non-infected patients who developed VTE over the same follow-up period. PE and DVT risk were evaluated using the Mantel-Haenszel random effects models with Hazard ratio (HR) as the effect measure with 95% confidence interval (CI) while heterogeneity was assessed using Higgins I2 statistic. Overall, 29.078.950 patients (mean age 50.2 years, 63.9% males), of which 2.060.496 had COVID-19 infection, were included. Over a mean follow-up of 8.5 months, the cumulative incidence of PE and DVT in COVID-19 recovered patients were 1.2% (95% CI:0.9-1.4, I2: 99.8%) and 2.3% (95% CI:1.7-3.0, I2: 99.7%), respectively. Recovered COVID-19 patients presented a higher risk of incident PE (HR: 3.16, 95% CI: 2.63-3.79, I2 = 90.1%) and DVT (HR: 2.55, 95% CI: 2.09-3.11, I2: 92.6%) compared to non-infected patients from the general population over the same follow-up period. Meta-regression showed a higher risk of PE and DVT with age and with female gender, and lower risk with longer follow-up. Recovered COVID-19 patients have a higher risk of VTE events, which increase with aging and among females.

Modulation of thromboinflammation in hospitalized COVID-19 patients with aprotinin, low molecular weight heparin, and anakinra: The DAWn-Antico study.

Background: Thromboinflammation plays a central role in severe COVID-19. The kallikrein pathway activates both inflammatory pathways and contact-mediated coagulation. We investigated if modulation of the thromboinflammatory response improves outcomes in hospitalized COVID-19 patients. Methods: In this multicenter open-label randomized clinical trial (EudraCT 2020-001739-28), patients hospitalized with COVID-19 were 1:2 randomized to receive standard of care (SOC) or SOC plus study intervention. The intervention consisted of aprotinin (2,000,000 IE IV four times daily) combined with low molecular weight heparin (LMWH; SC 50 IU/kg twice daily on the ward, 75 IU/kg twice daily in intensive care). Additionally, patients with predefined hyperinflammation received the interleukin-1 receptor antagonist anakinra (100 mg IV four times daily). The primary outcome was time to a sustained 2-point improvement on the 7-point World Health Organization ordinal scale for clinical status, or discharge. Findings: Between 24 June 2020 and 1 February 2021, 105 patients were randomized, and 102 patients were included in the full analysis set (intervention N = 67 vs. SOC N = 35). Twenty-five patients from the intervention group (37%) received anakinra. The intervention did not affect the primary outcome (HR 0.77 [CI 0.50-1.19], p = 0.24) or mortality (intervention n = 3 [4.6%] vs. SOC n = 2 [5.7%], HR 0.82 [CI 0.14-4.94], p = 0.83). There was one treatment-related adverse event in the intervention group (hematuria, 1.49%). There was one thrombotic event in the intervention group (1.49%) and one in the SOC group (2.86%), but no major bleeding. Conclusions: In hospitalized COVID-19 patients, modulation of thromboinflammation with high-dose aprotinin and LMWH with or without anakinra did not improve outcome in patients with moderate to severe COVID-19.

Dysregulation of the kallikrein-kinin system in bronchoalveolar lavage fluid of patients with severe COVID-19.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the angiotensin-converting enzyme 2 (ACE2) receptor, a critical component of the kallikrein-kinin system. Its dysregulation may lead to increased vascular permeability and release of inflammatory chemokines. Interactions between the kallikrein-kinin and the coagulation system might further contribute to thromboembolic complications in COVID-19. METHODS: In this observational study, we measured plasma and tissue kallikrein hydrolytic activity, levels of kinin peptides, and myeloperoxidase (MPO)-DNA complexes as a biomarker for neutrophil extracellular traps (NETs), in bronchoalveolar lavage (BAL) fluid from patients with and without COVID-19. FINDINGS: In BAL fluid from patients with severe COVID-19 (n = 21, of which 19 were mechanically ventilated), we observed higher tissue kallikrein activity (18·2 pM [1·2-1535·0], median [range], n = 9 vs 3·8 [0·0-22·0], n = 11; p = 0·030), higher levels of the kinin peptide bradykinin-(1-5) (89·6 [0·0-2425·0], n = 21 vs 0·0 [0·0-374·0], n = 19, p = 0·001), and higher levels of MPO-DNA complexes (699·0 ng/mL [66·0-142621·0], n = 21 vs 70·5 [9·9-960·0], n = 19, p < 0·001) compared to patients without COVID-19. INTERPRETATION: Our observations support the hypothesis that dysregulation of the kallikrein-kinin system might occur in mechanically ventilated patients with severe pulmonary disease, which might help to explain the clinical presentation of patients with severe COVID-19 developing pulmonary oedema and thromboembolic complications. Therefore, targeting the kallikrein-kinin system should be further explored as a potential treatment option for patients with severe COVID-19. FUNDING: Research Foundation-Flanders (G0G4720N, 1843418N), KU Leuven COVID research fund.

Thromboprophylaxis in COVID-19: Weight and severity adjusted intensified dosing.

Background: Venous thromboembolism (VTE) frequently occurs in hospitalized patients with coronavirus disease 2019 (COVID-19). The optimal dose of anticoagulation for thromboprophylaxis in COVID-19 is unknown. Aims: To report VTE incidence and bleeding before and after implementing a hospital-wide intensified thromboprophylactic protocol in patients with COVID-19. Methods: On March 31, 2020, we implemented an intensified thromboprophylactic protocol consisting of 50 IU anti-Xa low molecular weight heparin (LMWH)/kg once daily at the ward, twice daily at the intensive care unit (ICU). We included all patients hospitalized in a tertiary care hospital with symptomatic COVID-19 between March 7 and July 1, 2020. The primary outcome was the incidence of symptomatic or subclinical VTE and major bleeding during admission. Routine ultrasound screening for VTE was performed whenever logistically possible. Results: We included 412 patients, of which 116 were admitted to the ICU. Of 219 patients with standard a prophylactic dose of LMWH, 16 (7.3%) had VTE, 10 of which were symptomatic (4.6%). Of 193 patients with intensified thromboprophylaxis, there were no symptomatic VTE cases, three incidental deep venous thrombosis cases (1.6%), and one incidental pulmonary embolism (0.5%). The major bleeding rate was 1.2% in patients with intensified thromboprophylaxis and 7.7% when therapeutic anticoagulation was needed. Conclusion: In hospitalized patients with COVID-19, there were no additional symptomatic VTEs and a reduction in incidental deep vein thrombosis after implementing systematic thromboprophylaxis with weight-adjusted prophylactic (ward) to intermediate (ICU), but not therapeutic dosed anticoagulation. This intensified thromboprophylaxis was associated with a lower risk of major bleeding compared with therapeutic dosed anticoagulation.

Prevalence of Acute Pulmonary Embolism at Autopsy in Patients With COVID-19.

To date, the actual prevalence of acute pulmonary embolism (PE) in patients with SARS-CoV-2 infection remains unknown, as systematic screening for PE is cumbersome. We performed a systematic review and meta-analysis on autoptic data to estimate the prevalence of histopathologic findings of acute PE and its relevance as a cause of death on patients with COVID-19. We searched MEDLINE-PubMed and Scopus to locate all articles published in the English language, up to August 10, 2021, reporting the autoptic prevalence of acute PE and evaluating PE as the underlying cause of death in patients with COVID-19. The pooled prevalence for both outcomes was calculated using a random-effects model and presenting the related 95% confidence interval (CI). Statistical heterogeneity was measured using the Higgins I2 statistic. We analyzed autoptic data of 749 patients with COVID-19 (mean age 63.4 years) included in 14 studies. In 10 studies, based on 526 subjects (mean age 63.8 years), a random-effect model revealed that autoptic acute PE findings were present in 27.5% of cases (95% CI 15.0 to 45.0%, I2 89.9%). Conversely, in 429 COVID-19 subjects (mean age 64.0 years) enrolled in 9 studies, acute PE was the underlying cause of death in 19.9% of cases (95% CI 11.0 to 33.3%, I2 83.3%). Autoptic findings of acute PE in patients with COVID-19 are present in about 30% of subjects, whereas a venous thromboembolic event represents the underlying cause of death in about 1 of 4 patients.

Azithromycin for treatment of hospitalised COVID-19 patients: a randomised, multicentre, open-label clinical trial (DAWn-AZITHRO).

BACKGROUND AND OBJECTIVES: Azithromycin was rapidly adopted as a repurposed drug to treat coronavirus disease 2019 (COVID-19) early in the pandemic. We aimed to evaluate its efficacy in patients hospitalised for COVID-19. METHODS: In a series of randomised, open-label, phase 2 proof-of-concept, multicentre clinical trials (Direct Antivirals Working against the novel coronavirus (DAWn)), several treatments were compared with standard of care. In 15 Belgian hospitals, patients hospitalised with moderate to severe COVID-19 were allocated 2:1 to receive standard of care plus azithromycin or standard of care alone. The primary outcome was time to live discharge or sustained clinical improvement, defined as a two-point improvement on the World Health Organization (WHO) ordinal scale sustained for at least 3 days. RESULTS: Patients were included between April 22 and December 17, 2020. When 15-day follow-up data were available for 160 patients (56% of preset cohort), an interim analysis was performed at request of the independent Data Safety and Monitoring Board. Subsequently, DAWn-AZITHRO was stopped for futility. In total, 121 patients were allocated to the treatment arm and 64 patients to the standard-of-care arm. We found no effect of azithromycin on the primary outcome with a hazard ratio of 1.044 (95% CI 0.772-1.413; p=0.7798). None of the predefined subgroups showed significant interaction as covariates in the Fine-Gray regression analysis. No benefit of azithromycin was found on any of the short- and longer-term secondary outcomes. CONCLUSION: Time to clinical improvement is not influenced by azithromycin in patients hospitalised with moderate to severe COVID-19.

Early high antibody titre convalescent plasma for hospitalised COVID-19 patients: DAWn-plasma.

BACKGROUND: Several randomised clinical trials have studied convalescent plasma for coronavirus disease 2019 (COVID-19) using different protocols, with different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralising antibody titres, at different time-points and severities of illness. METHODS: In the prospective multicentre DAWn-plasma trial, adult patients hospitalised with COVID-19 were randomised to 4 units of open-label convalescent plasma combined with standard of care (intervention group) or standard of care alone (control group). Plasma from donors with neutralising antibody titres (50% neutralisation titre (NT50)) ≥1/320 was the product of choice for the study. RESULTS: Between 2 May 2020 and 26 January 2021, 320 patients were randomised to convalescent plasma and 163 patients to the control group according to a 2:1 allocation scheme. A median (interquartile range) volume of 884 (806-906) mL) convalescent plasma was administered and 80.68% of the units came from donors with neutralising antibody titres (NT50) ≥1/320. Median time from onset of symptoms to randomisation was 7 days. The proportion of patients alive and free of mechanical ventilation on day 15 was not different between both groups (convalescent plasma 83.74% (n=267) versus control 84.05% (n=137)) (OR 0.99, 95% CI 0.59-1.66; p=0.9772). The intervention did not change the natural course of antibody titres. The number of serious or severe adverse events was similar in both study arms and transfusion-related side-effects were reported in 19 out of 320 patients in the intervention group (5.94%). CONCLUSIONS: Transfusion of 4 units of convalescent plasma with high neutralising antibody titres early in hospitalised COVID-19 patients did not result in a significant improvement of clinical status or reduced mortality.

Repolarization abnormalities on admission predict 1-year outcome in COVID-19 patients.

BACKGROUND: ECG abnormalities in COVID-19 have been widely reported, however data after discharge is limited. The aim was to describe ECG abnormalities on admission and following recovery of COVID-19, and their associated mortality. METHODS: All patients hospitalized in a tertiary care hospital between March 7th and July 1st 2020 with COVID-19 were included in a retrospective registry. The first ECG on admission was collected, together with an ECG after hospital discharge in the absence of acute pathology. Automated measures and clinical ECG interpretations were collected. Multivariate Cox regression analysis was performed to predict 1-year all-cause mortality. RESULTS: In total 420 patients were included, of which 83 patients (19.8%) died during the 1-year follow-up period. Repolarization abnormalities were present in 189 patients (45.0%). The extent of repolarization abnormalities was an independent predictor of 1-year all-cause mortality (HR per region 1.30, 95%CI 1.04-1.64) together with age (/year HR 1.06, 95%CI 1.04-1.08), heart rate (/bpm HR 1.02, 95%CI 1.01-1.03), neurological disorders (HR 2.41, 95%CI 1.47-3.93), active cancer (HR 2.75, 95%CI 1.57-4.82), CRP (per 10 mg/L HR 1.05, 95%CI 1.02-1.08) and eGFR (per 10 mg/L HR 0.90, 95%CI 0.83-0.98).In 245 patients (68.1%) an ECG post discharge was available. New repolarization abnormalities were more frequent in patients who died after discharge (4.7% versus 41.7%, p < 0.001) and 8 (3.3%) had new ventricular conduction defects, none of whom died during follow-up. CONCLUSIONS: The presence and extent of repolarization abnormalities predicted outcome in patients with COVID-19. New repolarization abnormalities after discharge were associated with post-discharge mortality.

Tranexamic acid for the prevention and treatment of bleeding in surgery, trauma and bleeding disorders: a narrative review.

OBJECTIVES: We review the evidence for tranexamic acid (TXA) for the treatment and prevention of bleeding caused by surgery, trauma and bleeding disorders. We highlight therapeutic areas where evidence is lacking and discuss safety issues, particularly the concern regarding thrombotic complications. METHODS: An electronic search was performed in PubMed and the Cochrane Library to identify clinical trials, safety reports and review articles. FINDINGS: TXA reduces bleeding in patients with menorrhagia, and in patients undergoing caesarian section, myomectomy, hysterectomy, orthopedic surgery, cardiac surgery, orthognathic surgery, rhinoplasty, and prostate surgery. For dental extractions in patients with bleeding disorders or taking antithrombotic drugs, as well as in cases of idiopathic epistaxis, tonsillectomy, liver transplantation and resection, nephrolithotomy, skin cancer surgery, burn wounds and skin grafting, there is moderate evidence that TXA is effective for reducing bleeding. TXA was not effective in reducing bleeding in traumatic brain injury and upper and lower gastrointestinal bleeding. TXA reduces mortality in patients suffering from trauma and postpartum hemorrhage. For many of these indications, there is no consensus about the optimal TXA dose. With certain dosages and with certain indications TXA can cause harm, such as an increased risk of seizures after high TXA doses with brain injury and cardiac surgery, and an increased mortality after delayed administration of TXA for trauma events or postpartum hemorrhage. Whereas most trials did not signal an increased risk for thrombotic events, some trials reported an increased rate of thrombotic complications with the use of TXA for gastro-intestinal bleeding and trauma. CONCLUSIONS: TXA has well-documented beneficial effects in many clinical indications. Identifying these indications and the optimal dose and timing to minimize risk of seizures or thromboembolic events is work in progress.

Venous Thromboembolism in Patients Discharged after COVID-19 Hospitalization.

BACKGROUND: Venous thromboembolism (VTE) is a frequent complication of COVID-19, so that the importance of adequate in-hospital thromboprophylaxis in patients hospitalized with COVID-19 is well established. However, the incidence of VTE after discharge and whether postdischarge thromboprophylaxis is beneficial and safe are unclear. In this prospective observational single-center study, we report the incidence of VTE 6 weeks after hospitalization and the use of postdischarge thromboprophylaxis. METHODS: Patients hospitalized with confirmed COVID-19 were invited to a multidisciplinary follow-up clinic 6 weeks after discharge. D-dimer and C-reactive protein were measured, and all patients were screened for deep vein thrombosis with venous duplex-ultrasound. Additionally, selected high-risk patients received computed tomography pulmonary angiogram or ventilation-perfusion (V/Q) scan to screen for incidental pulmonary embolism. RESULTS: Of 485 consecutive patients hospitalized from March through June 2020, 146 patients were analyzed, of which 39% had been admitted to the intensive care unit (ICU). Postdischarge thromboprophylaxis was prescribed in 28% of patients, but was used more frequently after ICU stay (61%) and in patients with higher maximal D-dimer and C-reactive protein levels during hospitalization. Six weeks after discharge, elevated D-dimer values were present in 32% of ward and 42% of ICU patients. Only one asymptomatic deep vein thrombosis (0.7%) and one symptomatic pulmonary embolism (0.7%) were diagnosed with systematic screening. No bleedings were reported. CONCLUSION: In patients who had been hospitalized with COVID-19, systematic screening for VTE 6 weeks after discharge revealed a low incidence of VTE. A strategy of selectively providing postdischarge thromboprophylaxis in high-risk patients seems safe and potentially effective.

Itraconazole for COVID-19: preclinical studies and a proof-of-concept randomized clinical trial.

BACKGROUND: The antifungal drug itraconazole exerts in vitro activity against SARS-CoV-2 in Vero and human Caco-2 cells. Preclinical and clinical studies are required to investigate if itraconazole is effective for the treatment and/or prevention of COVID-19. METHODS: Due to the initial absence of preclinical models, the effect of itraconazole was explored in a clinical, proof-of-concept, open-label, single-center study, in which hospitalized COVID-19 patients were randomly assigned to standard of care with or without itraconazole. Primary outcome was the cumulative score of the clinical status until day 15 based on the 7-point ordinal scale of the World Health Organization. In parallel, itraconazole was evaluated in a newly established hamster model of acute SARS-CoV-2 infection and transmission, as soon as the model was validated. FINDINGS: In the hamster acute infection model, itraconazole did not reduce viral load in lungs, stools or ileum, despite adequate plasma and lung drug concentrations. In the transmission model, itraconazole failed to prevent viral transmission. The clinical trial was prematurely discontinued after evaluation of the preclinical studies and because an interim analysis showed no signal for a more favorable outcome with itraconazole: mean cumulative score of the clinical status 49 vs 47, ratio of geometric means 1.01 (95% CI 0.85 to 1.19) for itraconazole vs standard of care. INTERPRETATION: Despite in vitro activity, itraconazole was not effective in a preclinical COVID-19 hamster model. This prompted the premature termination of the proof-of-concept clinical study. FUNDING: KU Leuven, Research Foundation - Flanders (FWO), Horizon 2020, Bill and Melinda Gates Foundation.