Risk and Management of Bleeding Complications with Direct Oral Anticoagulants in Patients with Atrial Fibrillation and Venous Thromboembolism: a Narrative Review.

Atrial fibrillation (AF) and venous thromboembolism (VTE) are highly prevalent conditions with a significant healthcare burden, and represent the main indications for anticoagulation. Direct oral anticoagulants (DOACs) are the first choice treatment of AF/VTE, and have become the most prescribed class of anticoagulants globally, overtaking vitamin K antagonists (VKAs). Compared to VKAs, DOACs have a similar or better efficacy/safety profile, with reduced risk of intracerebral hemorrhage (ICH), while the risk of major bleeding and other bleeding harms may vary depending on the type of DOAC. We have critically reviewed available evidence from randomized controlled trials and observational studies regarding the risk of bleeding complications of DOACs compared to VKAs in patients with AF and VTE. Special patient populations (e.g., elderly, extreme body weights, chronic kidney disease) have specifically been addressed. Management of bleeding complications and possible resumption of anticoagulation, in particular after ICH and gastrointestinal bleeding, are also discussed. Finally, some suggestions are provided to choose the optimal DOAC to minimize adverse events according to individual patient characteristics and bleeding risk.

Potential mechanisms of vaccine-induced thrombosis.

Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a rare syndrome characterized by high-titer anti-platelet factor 4 (PF4) antibodies, thrombocytopenia and arterial and venous thrombosis in unusual sites, as cerebral venous sinuses and splanchnic veins. VITT has been described to occur almost exclusively after administration of ChAdOx1 nCoV-19 and Ad26.COV2.S adenovirus vector- based COVID-19 vaccines. Clinical and laboratory features of VITT resemble those of heparin-induced thrombocytopenia (HIT). It has been hypothesized that negatively charged polyadenylated hexone proteins of the AdV vectors could act as heparin to induce the conformational changes of PF4 molecule that lead to the formation of anti-PF4/polyanion antibodies. The anti-PF4 immune response in VITT is fostered by the presence of a proinflammatory milieu, elicited by some impurities found in ChAdOx1 nCoV-19 vaccine, as well as by soluble spike protein resulting from alternative splice events. Anti-PF4 antibodies bind PF4, forming immune complexes which activate platelets, monocytes and granulocytes, resulting in the VITT's immunothrombosis. The reason why only a tiny minority of patents receiving AdV-based COVID-19 vaccines develop VITT is still unknown. It has been hypothesized that individual intrinsic factors, either acquired (i.e., pre-priming of B cells to produce anti-PF4 antibodies by previous contacts with bacteria or viruses) or inherited (i.e., differences in platelet T-cell ubiquitin ligand-2 [TULA-2] expression) can predispose a few subjects to develop VITT. A better knowledge of the mechanistic basis of VITT is essential to improve the safety and the effectiveness of future vaccines and gene therapies using adenovirus vectors.

Vaccine-induced thrombotic thrombocytopenia: the elusive link between thrombosis and adenovirus-based SARS-CoV-2 vaccines.

The amazing effort of vaccination against COVID-19, with more than 2 billion vaccine doses administered all around the world as of 16 June 2021, has changed the history of this pandemic, drastically reducing the number of severe cases or deaths in countries were mass vaccination campaign have been carried out. However, the people's rising enthusiasm has been blunted in late February 2021 by the report of several cases of unusual thrombotic events in combination with thrombocytopenia after vaccination with ChAdOx1 nCov-19 (Vaxzevria), and a few months later also after Ad26.COV2. S vaccines. Of note, both products used an Adenovirus-based (AdV) platform to deliver the mRNA molecule - coding for the spike protein of SARS-CoV-2. A clinical entity characterized by cerebral and/or splanchnic vein thrombosis, often associated with multiple thromboses, with thrombocytopenia and bleeding, and sometimes disseminated intravascular coagulation (DIC), was soon recognized as a new syndrome, named vaccine-induced immune thrombotic thrombocytopenia (VITT) or thrombosis with thrombocytopenia syndrome (TTS). VITT was mainly observed in females under 55 years of age, between 4 and 16 days after receiving only Adenovirus-based vaccine and displayed a seriously high fatality rate. This prompted the Medicine Regulatory Agencies of various countries to enforce the pharmacovigilance programs, and to provide some advices to restrict the use of AdV-based vaccines to some age groups. This point-of view is aimed at providing a comprehensive review of epidemiological issues, pathogenetic hypothesis and treatment strategies of this rare but compelling syndrome, thus helping physicians to offer an up-to dated and evidence-based counseling to their often alarmed patients.

Anticoagulant interventions in hospitalized patients with COVID-19: A scoping review of randomized controlled trials and call for international collaboration.

INTRODUCTION: Coronavirus disease (COVID-19) is associated with a high incidence of thrombosis and mortality despite standard anticoagulant thromboprophylaxis. There is equipoise regarding the optimal dose of anticoagulant intervention in hospitalized patients with COVID-19 and consequently, immediate answers from high-quality randomized trials are needed. METHODS: The World Health Organization's International Clinical Trials Registry Platform was searched on June 17, 2020 for randomized controlled trials comparing increased dose to standard dose anticoagulant interventions in hospitalized COVID-19 patients. Two authors independently screened the full records for eligibility and extracted data in duplicate. RESULTS: A total of 20 trials were included in the review. All trials are open label, 5 trials use an adaptive design, 1 trial uses a factorial design, 2 trials combine multi-arm parallel group and factorial designs in flexible platform trials, and at least 15 trials have multiple study sites. With individual target sample sizes ranging from 30 to 3000 participants, the pooled sample size of all included trials is 12 568 participants. Two trials include only intensive care unit patients, and 10 trials base patient eligibility on elevated D-dimer levels. Therapeutic intensity anticoagulation is evaluated in 14 trials. All-cause mortality is part of the primary outcome in 14 trials. DISCUSSION: Several trials evaluate different dose regimens of anticoagulant interventions in hospitalized patients with COVID-19. Because these trials compete for sites and study participants, a collaborative effort is needed to complete trials faster, conduct pooled analyses and bring effective interventions to patients more quickly.

Multi-centre, three arm, randomized controlled trial on the use of methylprednisolone and unfractionated heparin in critically ill ventilated patients with pneumonia from SARS-CoV-2 infection: A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: To assess the hypothesis that an adjunctive therapy with methylprednisolone and unfractionated heparin (UFH) or with methylprednisolone and low molecular weight heparin (LMWH) are more effective in reducing any-cause mortality in critically-ill ventilated patients with pneumonia from SARS-CoV-2 infection compared to LMWH alone. TRIAL DESIGN: The study is designed as a multi-centre, interventional, parallel group, superiority, randomized, investigator sponsored, three arms study. Patients, who satisfy all inclusion criteria and no exclusion criteria, will be randomly assigned to one of the three treatment groups in a ratio 1:1:1. PARTICIPANTS: Inpatients will be recruited from 8 Italian Academic and non-Academic Intensive Care Units INCLUSION CRITERIA (ALL REQUIRED): 1. Positive SARS-CoV-2 diagnostic (on pharyngeal swab of deep airways material) 2. Positive pressure ventilation (either non-invasive or invasive) from > 24 hours 3. Invasive mechanical ventilation from < 96 hours 4. PaO2/FiO2 ratio lower than 150 mmHg 5. D-dimer level > 6 times the upper limit of normal reference range 6. C-reactive Protein > 6-fold upper the limit of normal reference range EXCLUSION CRITERIA: 1. Age < 18 years 2. On-going treatment with anticoagulant drugs 3. Platelet count < 100.000/mm3 4. History of heparin-induced thrombocytopenia 5. Allergy to sodium enoxaparin or other LMWH, UFH or methylprednisolone 6. Active bleeding or on-going clinical condition deemed at high risk of bleeding contraindicating anticoagulant treatment 7. Recent (in the last 1 month prior to randomization) brain, spinal or ophthalmic surgery 8. Chronic assumption or oral corticosteroids 9. Pregnancy or breastfeeding or positive pregnancy test. In childbearing age women, before inclusion, a pregnancy test will be performed if not available 10. Clinical decision to withhold life-sustaining treatment or "too sick to benefit" 11. Presence of other severe diseases impairing life expectancy (e.g. patients are not expected to survive 28 days given their pre-existing medical condition) 12. Lack or withdrawal of informed consent INTERVENTION AND COMPARATOR: • LMWH group: patients in this group will be administered enoxaparin at standard prophylactic dosage. • LMWH + steroid group: patients in this group will receive enoxaparin at standard prophylactic dosage and methylprednisolone. • UFH + steroid group: patients in this group will receive UFH at therapeutic dosages and methylprednisolone. UFH will be administered intravenously in UFH + steroid group at therapeutic doses. The infusion will be started at an infusion rate of 18 UI/kg/hour and then modified to obtain aPTT Ratio in between the range of 1.5-2.0. aPTT will be periodically checked at intervals no longer than 12 hours. The treatment with UFH will be administered up to ICU discharge. After ICU discharge anticoagulant therapy may be interrupted or switched to prophylaxis with LMWH in the destination ward up to clinical judgement of the attending physician. Enoxaparin will be administered in both LMWH group and LMWH + steroid group at standard prophylactic dose (i.e., 4000 UI once day, increased to 6000 UI once day for patients weighting more than 90 kg). The treatment will be administered subcutaneously once a day up to ICU discharge. After ICU discharge it may be continued or interrupted in the destination ward up to clinical judgement of the attending physician. Methylprednisolone will be administered in both LMWH + steroid group and UHF + steroid group intravenously with an initial bolus of 0,5 mg/kg followed by administration of 0,5 mg/kg 4 times daily for 7 days, 0,5 mg/kg 3 times daily from day 8 to day 10, 0,5 mg/kg 2 times daily at days 11 and 12 and 0,5 mg/kg once daily at days 13 and 14. MAIN OUTCOMES: Primary Efficacy Endpoint: All-cause mortality at day 28 Secondary Efficacy Endpoints: - Ventilation free days (VFDs) at day 28, defined as the total number of days that patient is alive and free of ventilation (either invasive or non-invasive) between randomization and day 28 (censored at hospital discharge). - Need of rescue administration of high-dose steroids or immune-modulatory drugs; - Occurrence of switch from non-invasive to invasive mechanical ventilation during ICU stay; - Delay from start of non-invasive ventilation to switch to invasive ventilation; - All-cause mortality at ICU discharge and hospital discharge; - ICU free days (IFDs) at day 28, defined as the total number of days between ICU discharge and day 28. - Occurrence of new infections from randomization to day 28; including infections by Candida, Aspergillus, Adenovirus, Herpes Virus e Cytomegalovirus - Occurrence of new organ dysfunction and grade of dysfunction during ICU stay. - Objectively confirmed venous thromboembolism, stroke or myocardial infarction; Safety endpoints: - Occurrence of major bleeding, defined as transfusion of 2 or more units of packed red blood cells in a day, bleeding that occurs in at least one of the following critical sites [intracranial, intra-spinal, intraocular (within the corpus of the eye; thus, a conjunctival bleed is not an intraocular bleed), pericardial, intra-articular, intramuscular with compartment syndrome, or retroperitoneal], bleeding that necessitates surgical intervention and bleeding that is fatal (defined as a bleeding event that was the primary cause of death or contributed directly to death); - Occurrence of clinically relevant non-major bleeding, defined ad acute clinically overt bleeding that does not meet the criteria for major and consists of any bleeding compromising hemodynamic; spontaneous hematoma larger than 25 cm2, intramuscular hematoma documented by ultrasonography, haematuria that was macroscopic and was spontaneous or lasted for more than 24 hours after invasive procedures; haemoptysis, hematemesis or spontaneous rectal bleeding requiring endoscopy or other medical intervention or any other bleeding requiring temporary cessation of a study drug. RANDOMIZATION: A block randomisation will be used with variable block sizes (block size 4-6-8), stratified by 3 factors: Centre, BMI (<30/≥30) and Age (<75/≥75). Central randomisation will be performed using a secure, web-based, randomisation system with an allocation ratio of 1:1:1. The allocation sequence will be generated by the study statistician using computer generated random numbers. BLINDING (MASKING): Participants to the study will be blinded to group assignment. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): The target sample size is based on the hypothesis that the combined use of UHF and steroid versus the LMWH group will significantly reduce the risk of death at day 28. The overall sample size in this study is expected to be 210 with a randomization 1:1:1 and seventy patients in each group. Assuming an alpha of 2.5% (two tailed) and mortality rate in LMWH group of 50%, as indicated from initial studies of ICU patients, the study will have an 80% power to detect at least a 25 % absolute reduction in the risk of death between: a) LMHW + steroid group and LMWH group or b) UHF + steroid group and LMWH group. The study has not been sized to assess the difference between LMHW + steroid group and UHF + steroid group, therefore the results obtained from this comparison will need to be interpreted with caution and will need further adequately sized studies confirm the effect. On the basis of a conservative estimation, that 8 participating sites admit an average of 3 eligible patients per month per centre (24 patients/month). Assuming that 80 % of eligible patients are enrolled, recruitment of 210 participants will be completed in approximately 10 months. TRIAL STATUS: Protocol version 1.1 of April 26th, 2020. Recruitment start (expected): September 1st, 2020 Recruitment finish (expected): June 30th, 2021 TRIAL REGISTRATION: EudraCT number 2020-001921-30 , registered on April 15th, 2020 AIFA approval on May 4th, 2020 FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

COVID-19, coagulopathy and venous thromboembolism: more questions than answers.

The acute respiratory illnesses caused by severe acquired respiratory syndrome corona Virus-2 (SARS-CoV-2) is a global health emergency, involving more than 8.6 million people worldwide with more than 450,000 deaths. Among the clinical manifestations of COVID-19, the disease that results from SARS-CoV-2 infection in humans, a prominent feature is a pro-thrombotic derangement of the hemostatic system, possibly representing a peculiar clinicopathologic manifestation of viral sepsis. The severity of the derangement of coagulation parameters in COVID-19 patients has been associated with a poor prognosis, and the use of low molecular weight heparin (LMWH) at doses registered for prevention of venous thromboembolism (VTE) has been endorsed by the World Health Organization and by Several Scientific societies. However, some relevant issues on the relationships between COVID-19, coagulopathy and VTE have yet to be fully elucidated. This review is particularly focused on four clinical questions: What is the incidence of VTE in COVID-19 patients? How do we frame the COVID-19 associated coagulopathy? Which role, if any, do antiphospolipid antibodies have? How do we tackle COVID-19 coagulopathy? In the complex scenario of an overwhelming pandemic, most everyday clinical decisions have to be taken without delay, although not yet supported by a sound scientific evidence. This review discusses the most recent findings of basic and clinical research about the COVID-associated coagulopathy, to foster a more thorough knowledge of the mechanisms underlying this compelling disease.

Randomised controlled trial comparing efficacy and safety of high versus low Low-Molecular Weight Heparin dosages in hospitalized patients with severe COVID-19 pneumonia and coagulopathy not requiring invasive mechanical ventilation (COVID-19 HD): a structured summary of a study protocol.

OBJECTIVES: To assess whether high doses of Low Molecular Weight Heparin (LMWH) (i.e. Enoxaparin 70 IU/kg twice daily) compared to standard prophylactic dose (i.e., Enoxaparin 4000 IU once day), in hospitalized patients with COVID19 not requiring Invasive Mechanical Ventilation [IMV], are: a)more effective in preventing clinical worsening, defined as the occurrence of at least one of the following events, whichever comes first: 1.Death2.Acute Myocardial Infarction [AMI]3.Objectively confirmed, symptomatic arterial or venous thromboembolism [TE]4.Need of either: a.Continuous Positive Airway Pressure (Cpap) or Non-Invasive Ventilation (NIV) orb.IMV in patients who at randomisation were receiving standard oxygen therapy5.IMV in patients who at randomisation were receiving non-invasive mechanical ventilationb)Similar in terms of major bleeding risk TRIAL DESIGN: Multicentre, randomised controlled, superiority, open label, parallel group, two arms (1:1 ratio), in-hospital study. PARTICIPANTS: Inpatients will be recruited from 7 Italian Academic and non-Academic Internal Medicine Units, 2 Infectious Disease Units and 1 Respiratory Disease Unit. INCLUSION CRITERIA (ALL REQUIRED): 1. Age > 18 and < 80 years 2. Positive SARS-CoV-2 diagnostic (on pharyngeal swab of deep airways material) 3. Severe pneumonia defined by the presence of at least one of the following criteria: a.Respiratory Rate ≥25 breaths /minb.Arterial oxygen saturation≤93% at rest on ambient airc.PaO2/FiO2 ≤300 mmHg 4. Coagulopathy, defined by the presence of at least one of the following criteria: a.D-dimer >4 times the upper level of normal reference rangeb.Sepsis-Induced Coagulopathy (SIC) score >4 5. No need of IMV EXCLUSION CRITERIA: 1. Age <18 and >80 years 2. IMV 3. Thrombocytopenia (platelet count < 80.000 mm3) 4. Coagulopathy: INR >1.5, aPTT ratio > 1.4 5. Impaired renal function (eGFR calculated by CKD-EPI Creatinine equation < 30 ml/min) 6. Known hypersensitivity to enoxaparin 7. History of heparin induced thrombocytopenia 8. Presence of an active bleeding or a pathology susceptible of bleeding in presence of anticoagulation (e.g. recent haemorrhagic stroke, peptic ulcer, malignant cancer at high risk of haemorrhage, recent neurosurgery or ophthalmic surgery, vascular aneurysms, arteriovenous malformations) 9. Concomitant anticoagulant treatment for other indications (e.g. atrial fibrillation, venous thromboembolism, prosthetic heart valves) 10. Concomitant double antiplatelet therapy 11. Administration of therapeutic doses of LMWH, fondaparinux, or unfractionated heparin (UFH) for more than 72 hours before randomization; prophylactic doses are allowed 12. Pregnancy or breastfeeding or positive pregnancy test 13. Presence of other severe diseases impairing life expectancy (e.g. patients are not expected to survive 28 days given their pre-existing medical condition) 14. Lack or withdrawal of informed consent INTERVENTION AND COMPARATOR: Control Group (Low-Dose LMWH): patients in this group will be administered Enoxaparin (Inhixa®) at standard prophylactic dose (i.e., 4000 UI subcutaneously once day). Intervention Group (High-Dose LMWH): patients in this group will be administered Enoxaparin (Inhixa®) at dose of 70 IU/kg every 12 hours, as reported in the following table. This dose is commonly used in Italy when a bridging strategy is required for the management of surgery or invasive procedures in patients taking anti-vitamin K oral anticoagulants Body Weight (kg)Enoxaparin dose every 12 hours (IU)<50200050-69400070-89600090-1108000>11010000 The treatment with Enoxaparin will be initiated soon after randomization (maximum allowed starting time 12h after randomization). The treatment will be administered every 12 hours in the intervention group and every 24 hours in the control group. Treatments will be administered in the two arms until hospital discharge or the primary outcomes detailed below occur. MAIN OUTCOMES: Primary Efficacy Endpoint: Clinical worsening, defined as the occurrence of at least one of the following events, whichever comes first: 1.Death2.Acute Myocardial Infarction [AMI]3.Objectively confirmed, symptomatic arterial or venous thromboembolism [TE]4.Need of either: a.Continuous Positive Airway Pressure (Cpap) or Non-Invasive Ventilation (NIV) orb.IMV in patients who at randomisation were in standard oxygen therapy by delivery interfaces5.Need for IMV, in patients who at randomisation were in Cpap or NIV Time to the occurrence of each of these events will be recorded. Clinical worsening will be analysed as a binary outcome as well as a time-to-event one. Secondary Efficacy Endpoints: Any of the following events occurring within the hospital stay 1.Death2.Acute Myocardial Infarction [AMI]3.Objectively confirmed, symptomatic arterial or venous thromboembolism [TE]4.Need of either: a.Continuous Positive Airway Pressure (Cpap) or Non-Invasive Ventilation (NIV) orb.IMV in patients who at randomisation were in standard oxygen therapy by delivery interfaces5.Need for IMV in patients who at randomisation were in Cpap or NIV6.Improvement of laboratory parameters of disease severity, including: o D-dimer levelo Plasma fibrinogen levelso Mean Platelet Volumeo Lymphocyte/Neutrophil ratioo IL-6 plasma levels MORTALITY AT 30 DAYS: Information about patients' status will be sought in those who are discharged before 30 days on Day 30 from randomisation. Time to the occurrence of each of these events will be recorded. Each of these events will be analysed as a binary outcome and as a time-to-event one. Primary safety endpoint: Major bleeding, defined as an acute clinically overt bleeding associated with one or more of the following: Decrease in haemoglobin of 2 g/dl or more;Transfusion of 2 or more units of packed red blood cells;Bleeding that occurs in at least one of the following critical sites [intracranial, intraspinal, intraocular (within the corpus of the eye; thus, a conjunctival bleed is not an intraocular bleed), pericardial, intra-articular, intramuscular with compartment syndrome, or retroperitoneal];Bleeding that is fatal (defined as a bleeding event that was the primary cause of death or contributed directly to death);Bleeding that necessitates surgical intervention Time to the occurrence of each of these events will be recorded. Each of these events will be analysed as a binary outcome and as a time-to-event one. Secondary safety endpoint: Clinically Relevant non-major bleeding, defined as an acute clinically overt bleeding that does not meet the criteria for major and consists of: 1.Any bleeding compromising hemodynamic2.Spontaneous hematoma larger than 25 cm2, or 100 cm2 if there was a traumatic cause3.Intramuscular hematoma documented by ultrasonography4.Epistaxis or gingival bleeding requiring tamponade or other medical intervention5.Bleeding from venipuncture for >5 minutes6.Haematuria that was macroscopic and was spontaneous or lasted for more than 24 hours after invasive procedures7.Haemoptysis, hematemesis or spontaneous rectal bleeding requiring endoscopy or other medical intervention8.Any other bleeding requiring temporary cessation of a study drug. Time to the occurrence of each of these events will be recorded. Each of these events will be analysed as a binary outcome and as a time-to-event one. RANDOMISATION: Randomisation (with a 1:1 randomisation ratio) will be centrally performed by using a secure, web-based system, which will be developed by the Methodological and Statistical Unit at the Azienda Ospedaliero-Universitaria of Modena. Randomisation stratified by 4 factors: 1) Gender (M/F); 2) Age (<75/≥75 years); 3) BMI (<30/≥30); 4) Comorbidities (0-1/>2) with random variable block sizes will be generated by STATA software. The web-based system will guarantee the allocation concealment. Blinding (masking) The study is conceived as open-label: patients and all health-care personnel involved in the study will be aware of the assigned group. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): The target sample size is based on the hypothesis that LMWH administered at high doses versus low doses will significantly reduce the risk of clinical worsening. The overall sample size in this study is expected to be 300 with 150 in the Low-Dose LMWH control group and 150 in the High-Dose LMWH intervention group, recruited over 10-11 months. Assuming an alpha of 5% (two tailed) and a percentage of patients who experience clinical worsening in the control group being between 25% and 30%, the study will have 80% power to detect at least 50% relative reduction in the risk of death between low and high doses of heparin. TRIAL STATUS: Protocol version 1.2 of 11/05/2020. Recruitment start (expected): 08/06/2020 Recruitment finish (expected): 30/04/2021 Trial registration EudraCT 2020-001972-13, registered on April 17th, 2020 Full protocol The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.