Dual Inhibition of Factor XIIa and Factor XIa Produces a Synergistic Anticoagulant Effect.

ABSTRACT: Clinical practice shows that a critical unmet need in the field of thrombosis prevention is the availability of anticoagulant therapy without bleeding risk. Inhibitors against FXIa or FXIIa have been extensively studied because of their low bleeding risk. However, whether these compounds produce synergistic effects has not yet been explored. In this study, analyses of activated partial thromboplastin time in combination with the FXIa inhibitor PN2KPI and the FXIIa inhibitor Infestin4 at different proportions were performed using the SynergyFinder tool identifying synergistic anticoagulation effects. Both an FeCl 3 -induced carotid artery thrombosis mouse model and a transient occlusion of the middle cerebral artery mouse model showed that the combination of PN2KPI and Infestin4, which are 28.57% and 6.25% of the effective dose, respectively, significantly prevents coagulation, and furthermore, dual inhibition does not cause bleeding risk.

Anticoagulants versus Antiplatelet Treatment in the Medical Management of Carotid Floating Thrombus.

BACKGROUND: Carotid free-floating thrombus (CFT) is a rare cause of stroke describing an intraluminal thrombus that is loosely associated with the arterial wall and manifesting as a filling defect fully surrounded by flow on vascular imaging. Unfortunately, there is no clear consensus among experts on the ideal treatment for this pathology. METHODS: Retrospective analysis of acute ischemic stroke (AIS) and transient ischemic attack (TIA) patients diagnosed with CFT on computed tomography angiogram (CTA) between January 2015-March 2023. We aimed to compare two treatment regimens: anticoagulation (ACT) and antiplatelet (APT) in the treatment of CFT. APT regimens included the use of dual or single antiplatelets (DAPT or SAPT; aspirin, clopidogrel and ticagrelor) and ACT regimens included the use of direct oral anticoagulants, warfarin, heparin or low molecular weight heparin +/- ASA. Patients that underwent mechanical thrombectomy were excluded. RESULTS: During study time there were 8252 acute ischemic stroke hospitalizations, of which 135 (1.63 %) patients were diagnosed with CFT. Sixty-six patients were included in our analysis. Patients assigned to APT were older (60.41years ± 12.82;p < 0.01). Other demographic variables were similar between ACT and APT groups. Complete CFT resolution on repeat vascular imaging was numerically higher at 30 days (58.8 vs 31.6 %, respectively; p = 0.1) and at latest follow-up (70.8 vs 50 %; p = 0.1) on ACT vs APT, respectively without reaching statistical significance. Similarly, there was numerically higher rates of any ICH with ACT compared to APT but it did not achieve statistical significance (27.6 % vs 13.5 %; p = 0.5). There were similar rates of PH1/2 hemorrhagic transformation, independence at discharge and similar hospital length of stay between ACT and APT groups. Patients assigned to APT were more likely to be discharged on their assigned treatment compared to those assigned to ACT (86.5 vs 55.2 %; p < 0.001). The rate of 30-day recurrent stroke was comparable among ACT and APT at 30 days (3.4 vs 0 %; p = 0.1, respectively). Subgroup analysis comparing exclusive ACT vs Dual APT lead to similar results. CONCLUSION: Our study showed comparable efficacy and safety outcomes in CFT patients who were exclusively managed medically with ACT vs APT. Larger prospective studies are needed.

Carotid free-floating thrombus in patients with acute ischaemic stroke and active cancer.

In patients with ischaemic stroke, a carotid free-floating thrombus (CFFT) raises diagnostic and therapeutic challenges. We describe two women, each taking tamoxifen for invasive non-metastatic breast cancer, who developed large-vessel occlusion ischaemic strokes. The first had a CFFT 24 hours after receiving intravenous thrombolysis and mechanical thrombectomy; the thrombus completely resolved after 1 week of therapeutic anticoagulation. The second had a tandem occlusion with a CFFT at admission; her neurological deficits rapidly improved after intravenous thrombolysis without needing a mechanical thrombectomy. However, subsequently, under therapeutic anticoagulation, distal migration of the CFFT caused a recurrent large vessel occlusion ischaemic stroke, requiring mechanical thrombectomy. The CTFF in both cases appeared to relate to a cancer-related prothrombotic state. Both received long-term oral anticoagulation and their tamoxifen was switched to anastrozole. At 3 months, both were functionally independent without recurrent vascular events.

Intravenously administered APAC, a dual AntiPlatelet AntiCoagulant, targets arterial injury site to inhibit platelet thrombus formation and tissue factor activity in mice.

INTRODUCTION: Arterial thrombosis is the main underlying mechanism of acute atherothrombosis. Combined antiplatelet and anticoagulant regimens prevent thrombosis but increase bleeding rates. Mast cell-derived heparin proteoglycans have local antithrombotic properties, and their semisynthetic dual AntiPlatelet and AntiCoagulant (APAC) mimetic may provide a new efficacious and safe tool for arterial thrombosis. We investigated the in vivo impact of intravenous APAC (0.3-0.5 mg/kg; doses chosen according to pharmacokinetic studies) in two mouse models of arterial thrombosis and the in vitro actions in mouse platelets and plasma. MATERIALS AND METHODS: Platelet function and coagulation were studied with light transmission aggregometry and clotting times. Carotid arterial thrombosis was induced either by photochemical injury or surgically exposing vascular collagen after infusion of APAC, UFH or vehicle. Time to occlusion, targeting of APAC to the vascular injury site and platelet deposition on these sites were assessed by intra-vital imaging. Tissue factor activity (TF) of the carotid artery and in plasma was captured. RESULTS: APAC inhibited platelet responsiveness to agonist stimulation (collagen and ADP) and prolonged APTT and thrombin time. After photochemical carotid injury, APAC-treatment prolonged times to occlusion in comparison with UFH or vehicle, and decreased TF both in carotid lysates and plasma. Upon binding from circulation to vascular collagen-exposing injury sites, APAC reduced the in situ platelet deposition. CONCLUSIONS: Intravenous APAC targets arterial injury sites to exert local dual antiplatelet and anticoagulant actions and attenuates thrombosis upon carotid injuries in mice. Systemic APAC provides local efficacy, highlighting APAC as a novel antithrombotic to reduce cardiovascular complications.

Nanoassemblies of Self-Immolative Boronate-Bridged Retinoic Acid Dimeric Prodrug as a Clot-Targeted Self-Deliverable Antithrombotic Nanomedicine.

All trans-retinoic acid (atRA) has potent anti-inflammatory and antiplatelet activity, but its clinical translation as an antithrombotic drug has been hampered by its low therapeutic efficacy. Here, we describe a facile and elegant strategy that converts atRA into systemically injectable antithrombotic nanoparticles. The strategy involves the dimerization of two atRA molecules using a self-immolative boronate linker that is cleaved specifically by hydrogen peroxide (H2O2) to release anti-inflammatory hydroxybenzyl alcohol (HBA), followed by dimerization-induced self-assembly to generate colloidally stable nanoparticles. The boronated atRA dimeric prodrug (BRDP) could form injectable nanoparticles in the presence of fucoidan that serves as an emulsifier and a targeting ligand to P-selectin overexpressed on the damaged endothelium. In response to H2O2, fucoidan-decorated BRDP (f-BRDP) nanoassemblies dissociate to release both atRA and HBA, while scavenging H2O2. In a mouse model of ferric chloride (FeCl3)-induced carotid arterial thrombosis, f-BRDP nanoassemblies target the thrombosed vessel and significantly inhibit thrombus formation. The results demonstrate that dimerization of atRA molecules via a boronate linker enables the formation of stable nanoassemblies with several benefits: high drug loading, drug self-delivery, on-demand multiple antithrombotic actions, and simple fabrication of nanoparticles. Overall, this strategy provides a promising expedient and practical route for the development of translational self-deliverable antithrombotic nanomedicine.

QiShen YiQi and its components attenuate acute thromboembolic stroke and carotid thrombosis by inhibition of CD62P/PSGL-1-mediated platelet-leukocyte aggregate formation.

BACKGROUND: QiShen YiQi (QSYQ) dropping pill, a component-based Chinese medicine consisting of benefiting Qi (YQ) and activating blood (HX) components, has been reported to exert a beneficial effect on cerebral ischemia-induced stroke. However, its efficacy and pharmacological mechanism on acute thromboembolic stroke is not clear. PURPOSE: This study is to explore the preventative effect and pharmacological mechanism of QSYQ and its YQ/HX components on the formation of platelet-leukocyte aggregation (PLA) in acute thromboembolic stroke. STUDY DESIGN AND METHODS: In vivo thromboembolic stroke model and FeCl3-induced carotid arterial occlusion models were used. Immunohistochemistry, Western blot, RT-qPCR, and flow cytometry experiments were performed to reveal the pharmacological mechanisms of QSYQ and its YQ/HX components. RESULTS: In thromboembolic stroke rats, QSYQ significantly attenuated infarct area, improved neurological recovery, reduced PLA formation, and inhibited P-selection (CD62P)/ P-selectin glycoprotein ligand-1 (PSGL-1) expressions. The YQ component preferentially down-regulated PSGL-1 expression in leukocyte, while the HX component preferentially down-regulated CD62P expression in platelet. In carotid arterial thrombosis mice, QSYQ and its YQ/HX components inhibited thrombus formation, prolonged vessel occlusion time, reduced circulating leukocytes and P-selectin expression. PLA formation and platelet/leukocyte adhesion to endothelial cell were also inhibited by QSYQ and its YQ/HX components in vitro. CONCLUSION: QSYQ and YQ/HX components attenuated thromboembolic stroke and carotid thrombosis by decreasing PLA formation via inhibiting CD62P/PSGL-1 expressions. This study shed a new light on the prevention of thromboembolic stroke.

Petrous Carotid Artery Thrombosis in an Immunocompromised Patient Presenting With Mastoiditis, A Case Report.

OBJECTIVES: The neurotologic literature commonly describes venous sinus thrombosis as a complication of mastoiditis. However, thrombosis of the internal carotid artery in the setting of mastoiditis is rarely described. We aim to document a case of carotid artery thrombosis in a patient presenting with mastoiditis. METHODS: We describe this case and review relevant literature. RESULTS: A renal transplant patient was transferred to our hospital with a left middle cerebral artery (MCA) infarct due to acute mastoiditis. Examination demonstrated middle ear effusion and radiologic workup confirmed mastoid infection adjacent to the site of arterial thrombosis. During cortical mastoidectomy and facial recess approach to the middle ear, the petrous carotid bone was found to be dehiscent with pneumatization of the petrous apex. Thrombosis was found to resolve following surgery, IV antibiotics and anticoagulation. Clinically, his focal neurological deficits improved. Proximity of the infectious process to an exposed petrous carotid artery supports the hypothesis that this patient's thrombus was a product of infectious spread and extra-luminal compression. CONCLUSION: To our knowledge, this is the first report of MCA infarction due to petrous ICA arterial thrombus in the setting of mastoid infection. The patient's immunocompromised state may have predisposed and contributed to the adverse outcome. We advocate for aggressive management of acute mastoiditis in the immunocompromised to prevent or manage complications (such as venous thrombophlebitis as well as ICA thrombus) as these patients don't show typical signs of infection and inflammation.

Panax Notoginseng Saponins Combined with Dual Antiplatelet Drugs Potentiates Anti-Thrombotic Effect with Alleviated Gastric Injury in A Carotid Artery Thrombosis Rat Model.

OBJECTIVE: To observe the combination effects of Panax notoginseng saponins (PNS)and dual antiplatelet drugs (DAPT), and to explore the mechanism via cyclooxygenase /prostaglandin pathway. METHODS: Right carotid artery thrombosis was induced in Wistar rats by infiltration with 70% FeCl3, and the animals were randomly divided into sham group, model group, DAPT group and PNS + DAPT group, intragastrically treated for 4 weeks. The cerebral pia mater microcirculation was observed in vivo after anesthetizing by anatomical microscope. The wet weight of carotid artery thrombosis was measured. Gastric mucosal injury was observed by hematoxylin and eosin staining. Platelet aggregation rate was detected with adenosine diphosphate -induced turbidimetry. Platelet CD62p expression was detected by flow cytometry. Concentrations of 6-Ketoprostaglandin F1 alpha, prostaglandin E2 in gastric mucosa and thromboxane B2, 6-Ketoprostaglandin F1 alpha, tissue plasminogen activator, plasminogen activator inhibitor, and fibrin fragment D in the plasma were measured by radioimmunoassay. RESULTS: PNS and DAPT increased the blood flow volume of cerebral pia mater and decreased erythrocyte aggregation and leukocyte adhesion of model rats. Compared to DAPT, PNS and DAPT further reduced the weight of carotid artery thrombosis with enhanced inhibition of platelet aggregation, increased tissue plasminogen activator levels and decreased fibrin fragment D levels. PNS and DAPT alleviated gastric injury induced by dual antiplatelet drugs and upregulated the expression of 6-Ketoprostaglandin F1 alpha in the gastric mucosa compared with DAPT. CONCLUSIONS: PNS combined with DAPT increased anti-thrombosis effects of DAPT and mitigated DAPT-related gastric injury. The underlying mechanisms may be associated with enhanced antiplatelet aggregation and activation of the fibrinolytic system and up-regulation of 6-Ketoprostaglandin F1 alpha expression in gastric mucosa.

Effects of MaiLiuPian on carotid thrombosis in rats and acute pulmonary embolism in mice and its antithrombotic mechanism.

Mailiupian (MLP) is a new patent functional food that consists of Crataegi Fructus, Notoginseng Radix, and Ginkgo Folium, which was reported to be active in improving the microcirculation based on formulation screening. However, whether it is effective in inhibiting thrombus and its mechanism has not been evaluated. Therefore, in the present study, the models of arterial thrombosis induced by FeCl3 and the models of APE by ADP were established to evaluate the antithrombosis effect of MLP. Results showed that MLP markedly reduced the weight and size of wet thrombosis in FeCl3 -induced rats and decreased the recovery time from symptoms of APE mice. MLP was proved to prolong APTT, PT, TT and improve the levels of t-PA and 6-keto-PGF1α significantly, meanwhile, PAI-1 and TXB2 were reduced apparently. By comparing tail bleeding time, MLP showed antithrombotic effects, but without the risk of bleeding, taking aspirin as a control. PRACTICAL APPLICATIONS: Our experiments proved that MLP, a new patent health food, acted on both coagulation and fibrinolytic systems and the platelet aggregation to play antithrombosis roles, providing a theoretical basis for applications of MLP in preventing or curing thrombosis diseases.

Milvexian, an orally bioavailable, small-molecule, reversible, direct inhibitor of factor XIa: In vitro studies and in vivo evaluation in experimental thrombosis in rabbits.

BACKGROUND: Milvexian (BMS-986177/JNJ-70033093) is an orally bioavailable factor XIa (FXIa) inhibitor currently in phase 2 clinical trials. OBJECTIVES: To evaluate in vitro properties and in vivo characteristics of milvexian. METHODS: In vitro properties of milvexian were evaluated with coagulation and enzyme assays, and in vivo profiles were characterized with rabbit models of electrolytic-induced carotid arterial thrombosis and cuticle bleeding time (BT). RESULTS: Milvexian is an active-site, reversible inhibitor of human and rabbit FXIa (Ki 0.11 and 0.38 nM, respectively). Milvexian increased activated partial thromboplastin time (APTT) without changing prothrombin time and potently prolonged plasma APTT in humans and rabbits. Milvexian did not alter platelet aggregation to ADP, arachidonic acid, or collagen. Milvexian was evaluated for in vivo prevention and treatment of thrombosis. For prevention, milvexian 0.063 + 0.04, 0.25 + 0.17, and 1 + 0.67 mg/kg+mg/kg/h preserved 32 ± 6*, 54 ± 10*, and 76 ± 5%* of carotid blood flow (CBF) and reduced thrombus weight by 15 ± 10*, 45 ± 2*, and 70 ± 4%*, respectively (*p < .05; n = 6/dose). For treatment, thrombosis was initiated for 15 min and CBF decreased to 40% of control. Seventy-five minutes after milvexian administration, CBF averaged 1 ± 0.3, 39 ± 10, and 66 ± 2%* in groups treated with vehicle and milvexian 0.25 + 0.17 and 1 + 0.67 mg/kg+mg/kg/h, respectively (*p < .05 vs. vehicle; n = 6/group). The combination of milvexian 1 + 0.67 mg/kg+mg/kg/h and aspirin 4 mg/kg/h intravenous did not increase BT versus aspirin monotherapy. CONCLUSIONS: Milvexian is an effective antithrombotic agent with limited impact on hemostasis, even when combined with aspirin in rabbits. This study supports inhibition of FXIa with milvexian as a promising antithrombotic therapy with a wide therapeutic window.

Discovery of Milvexian, a High-Affinity, Orally Bioavailable Inhibitor of Factor XIa in Clinical Studies for Antithrombotic Therapy.

Factor XIa (FXIa) is an enzyme in the coagulation cascade thought to amplify thrombin generation but has a limited role in hemostasis. From preclinical models and human genetics, an inhibitor of FXIa has the potential to be an antithrombotic agent with superior efficacy and safety. Reversible and irreversible inhibitors of FXIa have demonstrated excellent antithrombotic efficacy without increased bleeding time in animal models (Weitz, J. I., Chan, N. C. Arterioscler. Thromb. Vasc. Biol. 2019, 39 (1), 7-12). Herein, we report the discovery of a novel series of macrocyclic FXIa inhibitors containing a pyrazole P2' moiety. Optimization of the series for (pharmacokinetic) PK properties, free fraction, and solubility resulted in the identification of milvexian (BMS-986177/JNJ-70033093, 17, FXIa Ki = 0.11 nM) as a clinical candidate for the prevention and treatment of thromboembolic disorders, suitable for oral administration.

COVID-19-associated ischaemic stroke due to underlying carotid artery thrombosis in a healthy young woman.

SARS-CoV-2 has proven its versatility in host presentations; one such presentation is a hypercoagulable state causing large-vessel thrombosis. We report a case on a previously asymptomatic COVID-19-positive patient presenting with an acute ischaemic stroke and an incidental left internal carotid artery thrombus. The patient's medical, social and family history and hypercoagulability screening excluded any other explanation for the left carotid thrombus or stroke, except for testing positive for the COVID-19. This case explores the known hypercoagulable state associated with COVID-19 and the effect of the virus on the host's immune response. It also questions whether administration of recombinant tissue plasminogen activator (t-PA), according to the American Heart Association guidelines, following a negative head CT for haemorrhagic stroke is safe without prior extended imaging in this patient population. We recommend, in addition to obtaining a non-contrast CT scan of the brain, a CT angiogram or carotid duplex of the neck be obtained routinely in patients with COVID-19 exhibiting stroke symptoms before t-PA administration as the effects may be detrimental. This recommendation will likely prevent fragmentation and embolisation of an undetected carotid thrombus.

Adverse Effects of Oseltamivir Phosphate Therapy on the Liver of LDLR-/- Mice Without Any Benefit on Atherosclerosis and Thrombosis.

ABSTRACT: Desialylation, governed by sialidases or neuraminidases, is strongly implicated in a wide range of human disorders, and accumulative data show that inhibition of neuraminidases, such as neuraminidases 1 sialidase, may be useful for managing atherosclerosis. Several studies have reported promising effects of oseltamivir phosphate, a widely used anti-influenza sialidase inhibitor, on human cancer cells, inflammation, and insulin resistance. In this study, we evaluated the effects of oseltamivir phosphate on atherosclerosis and thrombosis and potential liver toxicity in LDLR-/- mice fed with high-fat diet. Our results showed that oseltamivir phosphate significantly decreased plasma levels of LDL cholesterol and elastin fragmentation in aorta. However, no effect was observed on both atherosclerotic plaque size in aortic roots and chemically induced thrombosis in carotid arteries. Importantly, oseltamivir phosphate administration had adverse effects on the liver of mice and significantly increased messenger RNA expression levels of F4/80, interleukin-1ß, transforming growth factor-ß1, matrix metalloproteinase-12, and collagen. Taken together, our findings suggest that oseltamivir phosphate has limited benefits on atherosclerosis and carotid thrombosis and may lead to adverse side effects on the liver with increased inflammation and fibrosis.

Diagnóstico y tratamiento del trombo móvil carotídeo. A propósito de un caso / Diagnosis and treatment of a mobile carotid thrombus. A case report

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Internal carotid artery thrombosis in COVID 19 / Trombosis de arteria carótida interna en COVID 19

Abstract Case description: 37-year-old female with PCR-RT swab for COVID-19 positive, with neurological manifestation as a result of internal carotid artery occlusion. Clinical findings: Nasal congestion and sneezing of 5 days duration; pulsatile headache in the left hemicranium 3 days prior to admission, with intensity 6/10 according to the visual analogue scale, accompanied by phosphenes, photophobia and diplopia; with subsequent developing right hemiparesis over a 26-hour period. Treatment and result: She was given medical management with oral antiplatelet agents and anticoagulants (subcutaneous and oral) during his hospitalization, it was not possible to perform thrombolysis and thrombectomy due to the high risk of complications. He was discharged at 14 days, without functional limitation, symmetrical strength in upper and lower limbs, bilateral visual acuity 20/20, denying headache. Clinical relevance: The case presented here describes a pattern in how data supporting an association between COVID-19 and stroke in young populations with or without typical vascular risk factors, sometimes with only mild respiratory symptoms, is increasing. Prospective studies are required to further evaluate this association, as well as anticoagulation studies to prevent these potentially life-threatening events.

Resumen Descripción del caso: Mujer de 37 años con hisopado PCR-RT para COVID-19 positivo, con manifestación neurológica por oclusión de la arteria carótida interna. Hallazgos clínicos: Congestión nasal y estornudos de 5 días de duración; cefalea pulsátil en hemicráneo izquierdo 3 días antes del ingreso, con intensidad 6/10 según la escala visual analógica, acompañada de fosfenos, fotofobia y diplopía; con posterior desarrollo de hemiparesia derecha durante un período de 26 horas. Tratamiento y resultado: Se le brindó manejo médico con antiagregantes plaquetarios orales y anticoagulantes (subcutáneos y orales) durante su internación, no fue posible realizar trombólisis y trombectomía por alto riesgo de complicaciones. Fue dado de alta a los 14 días, sin limitación funcional, fuerza simétrica en miembros superiores e inferiores, agudeza visual bilateral 20/20, negando cefalea. Relevancia clínica: Se describe un patrón que indica cómo están aumentando los datos que apoyan una asociación entre COVID-19 y el accidente cerebrovascular en poblaciones jóvenes con o sin factores de riesgo vascular típicos, a veces con solo síntomas respiratorios leves. Se requieren estudios prospectivos para evaluar más a fondo esta asociación, así como estudios de anticoagulación para prevenir estos eventos potencialmente mortales.

NADPH oxidase 1 is a novel pharmacological target for the development of an antiplatelet drug without bleeding side effects.

Growing evidence supports a central role of NADPH oxidases (NOXs) in the regulation of platelets, which are circulating cells involved in both hemostasis and thrombosis. Here, the use of Nox1-/- and Nox1+/+ mice as experimental models of human responses demonstrated a critical role of NOX1 in collagen-dependent platelet activation and pathological arterial thrombosis, as tested in vivo by carotid occlusion assays. In contrast, NOX1 does not affect platelet responses to thrombin and normal hemostasis, as assayed in tail bleeding experiments. Therefore, as NOX1 inhibitors are likely to have antiplatelet effects without associated bleeding risks, the NOX1-selective inhibitor 2-acetylphenothiazine (2APT) and a series of its derivatives generated to increase inhibitory potency and drug bioavailability were tested. Among the 2APT derivatives, 1-(10H-phenothiazin-2-yl)vinyl tert-butyl carbonate (2APT-D6) was selected for its high potency. Both 2APT and 2APT-D6 inhibited collagen-dependent platelet aggregation, adhesion, thrombus formation, superoxide anion generation, and surface activation marker expression, while responses to thrombin or adhesion to fibrinogen were not affected. In vivo administration of 2APT or 2APT-D6 led to the inhibition of mouse platelet aggregation, oxygen radical output, and thrombus formation, and carotid occlusion, while tail hemostasis was unaffected. Differently to in vitro experiments, 2APT-D6 and 2APT displayed similar potency in vivo. In summary, NOX1 inhibition with 2APT or its derivative 2APT-D6 is a viable strategy to control collagen-induced platelet activation and reduce thrombosis without deleterious effects on hemostasis. These compounds should, therefore, be considered for the development of novel antiplatelet drugs to fight cardiovascular diseases in humans.

Macrothrombosis and stroke in patients with mild Covid-19 infection.

Coronavirus disease 2019 (COVID-19) is a pandemic disease currently affecting millions of people worldwide. Its neurological implications are poorly understood, and further study is urgently required. A hypercoagulable state has been reported in patients with severe COVID-19, but nothing is known about coagulopathy in patients with milder disease. We describe cases of patients in New York City presenting with stroke secondary to large vessel thrombosis without occlusion, incidentally found to have COVID-19 with only mild respiratory symptoms. This is in contrast to the venous thrombosis and microangiopathy that has been reported in patients with severe COVID-19. Our cases suggest that even in the absence of severe disease, patients with COVID-19 may be at increased risk of thrombus formation leading to stroke, perhaps resulting from viral involvement of the endothelium. Further systematic study is needed because this may have implications for primary and secondary stroke prevention in patients with COVID-19.

Huge Free-Floating Thrombus in the Internal Carotid Artery Under Duplex Ultrasound Surveillance: A Case Report.

INTRODUCTION: Carotid free-floating thrombus (FFT) is an unusual finding in acute ischemic stroke. Atherosclerosis is the most common etiology of FFT formation. CASE REPORT: Here we report a 42-year-old male patient admitted to our department with left temporal and parietal lobe ischemic stroke with normal magnetic resonance angiography. A huge FFT in the left internal carotid artery were found by duplex ultrasound. Acute thrombosis based on atherosclerotic plaque were considered as the reason of this embolization. The thrombus shrunk significantly under anticoagulation and antiplatelet treatment. CONCLUSIONS: Evaluation of the intracranial vessel in the emergency is not enough and early carotid duplex ultrasound can help find of the FFT in time, which help to choose the early intervene by neurosurgeon. Early antithrombotic treatment can be a safe treatment option for reducing huge thrombus based on the nature of thrombus formation. Computed tomography angiography and high-resolution magnetic resonance imaging to certify the character of the plaque are recommended for plaque evaluation.

Internal carotid artery thrombosis in COVID 19.

CASE DESCRIPTION: 37-year-old female with PCR-RT swab for COVID-19 positive, with neurological manifestation as a result of internal carotid artery occlusion. CLINICAL FINDINGS: Nasal congestion and sneezing of 5 days duration; pulsatile headache in the left hemicranium 3 days prior to admission, with intensity 6/10 according to the visual analogue scale, accompanied by phosphenes, photophobia and diplopia; with subsequent developing right hemiparesis over a 26-hour period. TREATMENT AND RESULT: She was given medical management with oral antiplatelet agents and anticoagulants (subcutaneous and oral) during his hospitalization, it was not possible to perform thrombolysis and thrombectomy due to the high risk of complications. He was discharged at 14 days, without functional limitation, symmetrical strength in upper and lower limbs, bilateral visual acuity 20/20, denying headache. CLINICAL RELEVANCE: The case presented here describes a pattern in how data supporting an association between COVID-19 and stroke in young populations with or without typical vascular risk factors, sometimes with only mild respiratory symptoms, is increasing. Prospective studies are required to further evaluate this association, as well as anticoagulation studies to prevent these potentially life-threatening events.

DESCRIPCIÓN DEL CASO: Mujer de 37 años con hisopado PCR-RT para COVID-19 positivo, con manifestación neurológica por oclusión de la arteria carótida interna. HALLAZGOS CLÍNICOS: Congestión nasal y estornudos de 5 días de duración; cefalea pulsátil en hemicráneo izquierdo 3 días antes del ingreso, con intensidad 6/10 según la escala visual analógica, acompañada de fosfenos, fotofobia y diplopía; con posterior desarrollo de hemiparesia derecha durante un período de 26 horas. TRATAMIENTO Y RESULTADO: Se le brindó manejo médico con antiagregantes plaquetarios orales y anticoagulantes (subcutáneos y orales) durante su internación, no fue posible realizar trombólisis y trombectomía por alto riesgo de complicaciones. Fue dado de alta a los 14 días, sin limitación funcional, fuerza simétrica en miembros superiores e inferiores, agudeza visual bilateral 20/20, negando cefalea. RELEVANCIA CLÍNICA: Se describe un patrón que indica cómo están aumentando los datos que apoyan una asociación entre COVID-19 y el accidente cerebrovascular en poblaciones jóvenes con o sin factores de riesgo vascular típicos, a veces con solo síntomas respiratorios leves. Se requieren estudios prospectivos para evaluar más a fondo esta asociación, así como estudios de anticoagulación para prevenir estos eventos potencialmente mortales.