Venous thromboembolism secondary to hospitalization for COVID-19: patient management and long-term outcomes.

Background: Venous thromboembolism (VTE) is a complication of COVID-19 in hospitalized patients. Little information is available on long-term outcomes of VTE in this population. Objectives: We aimed to compare the characteristics, management strategies, and long-term clinical outcomes between patients with COVID-19-associated VTE and patients with VTE provoked by hospitalization for other acute medical illnesses. Methods: This is an observational cohort study, with a prospective cohort of 278 patients with COVID-19-associated VTE enrolled between 2020 and 2021 and a comparison cohort of 300 patients without COVID-19 enrolled in the ongoing START2-Register between 2018 and 2020. Exclusion criteria included age <18 years, other indications to anticoagulant treatment, active cancer, recent (<3 months) major surgery, trauma, pregnancy, and participation in interventional studies. All patients were followed up for a minimum of 12 months after treatment discontinuation. Primary end point was the occurrence of venous and arterial thrombotic events. Results: Patients with VTE secondary to COVID-19 had more frequent pulmonary embolism without deep vein thrombosis than controls (83.1% vs 46.2%, P <.001), lower prevalence of chronic inflammatory disease (1.4% and 16.3%, P <.001), and history of VTE (5.0% and 19.0%, P <.001). The median duration of anticoagulant treatment (194 and 225 days, P = 0.9) and the proportion of patients who discontinued anticoagulation (78.0% and 75.0%, P = 0.4) were similar between the 2 groups. Thrombotic event rates after discontinuation were 1.5 and 2.6 per 100 patient-years, respectively (P = 0.4). Conclusion: The risk of recurrent thrombotic events in patients with COVID-19-associated VTE is low and similar to the risk observed in patients with VTE secondary to hospitalization for other medical diseases.

Endothelial dysfunction, oxidative stress and low-grade endotoxemia in COVID-19 patients hospitalised in medical wards.

BACKGROUND: Endothelial dysfunction, assessed by flow-mediated dilation (FMD), is related to poor prognosis in patients with COVID-19 pneumonia (CP). In this study, we explored the interplay among FMD, NADPH oxidase type 2 (NOX-2) and lipopolysaccharides (LPS) in hospitalised patients with CP, community acquired pneumonia (CAP) and controls (CT). METHODS: We enrolled 20 consecutive patients with CP, 20 hospitalised patients with CAP and 20 CT matched for sex, age, and main cardiovascular risk factors. In all subjects we performed FMD and collected blood samples to analyse markers of oxidative stress (soluble Nox2-derived peptide (sNOX2-dp), hydrogen peroxide breakdown activity (HBA), nitric oxide (NO), hydrogen peroxide (H2O2)), inflammation (TNF-α and IL-6), LPS and zonulin levels. RESULTS: Compared with controls, CP had significant higher values of LPS, sNOX-2-dp, H2O2,TNF-α, IL-6 and zonulin; conversely FMD, HBA and NO bioavailability were significantly lower in CP. Compared to CAP patients, CP had significantly higher levels of sNOX2-dp, H2O2, TNF-α, IL-6, LPS, zonulin and lower HBA. Simple linear regression analysis showed that FMD inversely correlated with sNOX2-dp, H2O2, TNF-α, IL-6, LPS and zonulin; conversely FMD was directly correlated with NO bioavailability and HBA. Multiple linear regression analysis highlighted LPS as the only predictor of FMD. CONCLUSION: This study shows that patients with COVID-19 have low-grade endotoxemia that could activate NOX-2, generating increased oxidative stress and endothelial dysfunction.

A Comprehensive Review of Risk Factors for Venous Thromboembolism: From Epidemiology to Pathophysiology.

Venous thromboembolism (VTE) is the third most common cause of death worldwide. The incidence of VTE varies according to different countries, ranging from 1-2 per 1000 person-years in Western Countries, while it is lower in Eastern Countries (<1 per 1000 person-years). Many risk factors have been identified in patients developing VTE, but the relative contribution of each risk factor to thrombotic risk, as well as pathogenetic mechanisms, have not been fully described. Herewith, we provide a comprehensive review of the most common risk factors for VTE, including male sex, diabetes, obesity, smoking, Factor V Leiden, Prothrombin G20210A Gene Mutation, Plasminogen Activator Inhibitor-1, oral contraceptives and hormonal replacement, long-haul flight, residual venous thrombosis, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, trauma and fractures, pregnancy, immobilization, antiphospholipid syndrome, surgery and cancer. Regarding the latter, the incidence of VTE seems highest in pancreatic, liver and non-small cells lung cancer (>70 per 1000 person-years) and lowest in breast, melanoma and prostate cancer (<20 per 1000 person-years). In this comprehensive review, we summarized the prevalence of different risk factors for VTE and the potential molecular mechanisms/pathogenetic mediators leading to VTE.

VENOUS THROMBOEMBOLISM SECONDARY TO HOSPITALIZATION FOR COVID-19 DISEASE: PATIENT MANAGEMENT AND LONG-TERM OUTCOMES

Background Venous thromboembolism (VTE) is a complication of COVID-19 in hospitalized patients. Little information is available on long-term outcomes of VTE in this population. We compared characteristics, management strategies, and long-term clinical outcomes between patients with COVID-19 associated VTE and patients with VTE provoked by hospitalization for other acute medical illnesses. Methods Observational cohort study, with a prospective cohort of 278 COVID-19 patients with VTE enrolled between 2020 and 2021 and a comparison cohort of 300 non-COVID-19 patients enrolled in the ongoing START2-registry between 2018 and 2020. Exclusion criteria included age <18 years, other indications to anticoagulant treatment, active cancer, recent (<3 months) major surgery, trauma, pregnancy, participation in interventional studies. All patients were followed-up for a minimum of 12 months after treatment discontinuation. Primary endpoint was the occurrence of venous and arterial thrombotic events. Results Patients with VTE secondary to COVID-19 had more frequently PE without DVT than controls (83.1% vs 46.2%, p<0.001) and a lower prevalence of chronic inflammatory disease (1.4% and 16.3%,p<0.001) and history of VTE (5.0% and 19.0%, p<0.001). The median duration of anticoagulant treatment (194 and 225 days, p=n.s.) and the proportion of patients who discontinued anticoagulation (78.0% and 75.0%, p=n.s.) were similar between the two groups. Thrombotic event rates after discontinuation were 1.5 and 2.6 per 100 patient-years, respectively (p=n.s.). Conclusions The risk of recurrent thrombotic events in patients with COVID-19 associated VTE is low and similar to the risk observed in patients with VTE secondary to hospitalization for other medical diseases.

External validation of the ADA score for predicting thrombosis among acutely ill hospitalized medical patients from the APEX Trial.

The ADA (Age-D-dimer-Albumin) score was developed to identify hospitalized patients at an increased risk for thrombosis in the coronavirus infectious disease-19 (COVID-19) setting. The study aimed to validate the ADA score for predicting thrombosis in a non-COVID-19 medically ill population from the APEX trial. The APEX trial was a multinational, randomized trial that evaluated the efficacy and safety of betrixaban vs. enoxaparin among acutely ill hospitalized patients at risk for venous thromboembolism. The study endpoints included the composite of arterial or venous thrombosis and its components. Metrics of model calibration and discrimination were computed for assessing the performance of the ADA score as compared to the IMPROVE score, a well-validated VTE risk assessment model. Among 7,119 medical inpatients, 209 (2.9%) had a thrombosis event up to 77 days of follow-up. The ADA score demonstrated good calibration for both arterial and venous thrombosis, whereas the IMPROVE score had adequate calibration for venous thrombosis (p > 0.05 from the Hosmer-Lemeshow test). For discriminating arterial and venous thrombosis, there was no significant difference between the ADA vs. IMPROVE score (c statistic = 0.620 [95% CI: 0.582 to 0.657] vs. 0.590 [95% CI: 0.556 to 0.624]; ∆ c statistic = 0.030 [95% CI: -0.022 to 0.081]; p = 0.255). Similarly, for discriminating arterial thrombosis, there was no significant difference between the ADA vs. IMPROVE score (c statistic = 0.582 [95% CI: 0.534 to 0.629] vs. 0.609 [95% CI: 0.564 to 0.653]; ∆ c statistic = -0.027 [95% CI: -0.091 to 0.036]; p = 0.397). For discriminating venous thrombosis, the ADA score was modestly superior to the IMPROVE score (c statistic = 0.664 [95% CI: 0.607 to 0.722] vs. 0.573 [95% CI: 0.521 to 0.624]; ∆ c statistic = 0.091 [95% CI: 0.011 to 0.172]; p = 0.026). The ADA score had a higher sensitivity (0.579 [95% CI: 0.512 to 0.646]; vs. 0.440 [95% CI: 0.373 to 0.507]) but lower specificity (0.625 [95% CI: 0.614 to 0.637] vs. 0.747 [95% CI: 0.737 to 0.758]) than the IMPROVE score for predicting thrombosis. Among acutely ill hospitalized medical patients enrolled in the APEX trial, the ADA score demonstrated good calibration but suboptimal discrimination for predicting thrombosis. The findings support the use of either the ADA or IMPROVE score for thrombosis risk assessment. The applicability of the ADA score to non-COVID-19 populations warrants further research.Clinical Trial Registration: http://www.clinicaltrials.gov . Unique identifier: NCT01583218.

Association between PaO2/FiO2 ratio and thrombotic events in COVID-19 patients.

PaO2/FiO2 (P/F ratio) is considered a marker of hypoxia/hypoxemia and mortality. Several prothrombotic changes are associated with the decrease of P/F ratio. The role of P/F ratio in patients with arterial and venous thrombosis remains unclear. The aim of this study was to assess in patients with coronavirus disease 2019 (COVID-19), the association between P/F ratio and arterial/venous thrombosis. One thousand and four hundred and six COVID-19 patients were recruited; 289 (21%) patients had P/F ratio < 200 and 1117 (79%) ≥ 200. Compared to the patients with P/F ratio ≥ 200, those with P/F ratio < 200 were older and with higher levels of glycemia, D-dimer and lower levels of albumin. Multiple linear regression analysis showed that albumin (standardized coefficient ß:  0.156; SE: 0.001; p = 0.0001) and D-dimer (standardized coefficient ß: -0.135; SE: 0.0001; p = 0.0001) were associated with P/F ratio. During the hospitalization 159 patients were transferred in intensive care unit (ICU), 253 patients died, 156 patients had arterial or venous thrombotic events. A bivariate logistic analysis was performed to analyze the predictors of thrombosis in COVID-19 patients; P/F ratio < 200 (Odds Ratio: [OR] 1.718, 95% Confidence Interval [CI] 1.085-2.718, p = 0.021), albumin (OR 1.693, 95% CI 1.055-2.716, p = 0.029), D-dimer (OR 3.469, 95% CI 2.110-5.703, p < 0.0001), coronary artery disease (CAD) (OR 1.800, 95% CI 1.086-2.984, p = 0.023) and heart failure (OR 2.410 95% CI 1.385-4.193, p = 0.002) independently predicted thrombotic events in this population. This study suggests that the P/F ratio is associated with thrombotic events by promoting a hypercoagulation state in patients hospitalized for COVID-19.

Toll-Like Receptor 4-Dependent Platelet-Related Thrombosis in SARS-CoV-2 Infection.

BACKGROUND: SARS-CoV-2 is associated with an increased risk of venous and arterial thrombosis, but the underlying mechanism is still unclear. METHODS: We performed a cross-sectional analysis of platelet function in 25 SARS-CoV-2 and 10 healthy subjects by measuring Nox2 (NADPH oxidase 2)-derived oxidative stress and thromboxane B2, and investigated if administration of monoclonal antibodies against the S protein (Spike protein) of SARS-CoV-2 affects platelet activation. Furthermore, we investigated in vitro if the S protein of SARS-CoV-2 or plasma from SARS-CoV-2 enhanced platelet activation. RESULTS: Ex vivo studies showed enhanced platelet Nox2-derived oxidative stress and thromboxane B2 biosynthesis and under laminar flow platelet-dependent thrombus growth in SARS-CoV-2 compared with controls; both effects were lowered by Nox2 and TLR4 (Toll-like receptor 4) inhibitors. Two hours after administration of monoclonal antibodies, a significant inhibition of platelet activation was observed in patients with SARS-CoV-2 compared with untreated ones. In vitro study showed that S protein per se did not elicit platelet activation but amplified the platelet response to subthreshold concentrations of agonists and functionally interacted with platelet TLR4. A docking simulation analysis suggested that TLR4 binds to S protein via three receptor-binding domains; furthermore, immunoprecipitation and immunofluorescence showed S protein-TLR4 colocalization in platelets from SARS-CoV-2. Plasma from patients with SARS-CoV-2 enhanced platelet activation and Nox2-related oxidative stress, an effect blunted by TNF (tumor necrosis factor) α inhibitor; this effect was recapitulated by an in vitro study documenting that TNFα alone promoted platelet activation and amplified the platelet response to S protein via p47phox (phagocyte oxidase) upregulation. CONCLUSIONS: The study identifies 2 TLR4-dependent and independent pathways promoting platelet-dependent thrombus growth and suggests inhibition of TLR4. or p47phox as a tool to counteract thrombosis in SARS-CoV-2.

Asymptomatic and symptomatic deep venous thrombosis in hospitalized acutely ill medical patients: risk factors and therapeutic implications.

BACKGROUND: Acutely ill medical patients experience deep venous thrombosis (DVT) during the hospitalization, however the time course of DVT is still unclear. OBJECTIVES: To evaluate risk factors in acutely ill hospitalized medical patients for proximal asymptomatic DVT (ADVT) and symptomatic DVT (SDVT) at admission and discharge. PATIENTS/METHODS: In this prospective observational study, consecutive acutely ill medical patients (hospitalized mainly for acute medical disease as infections, neoplasm, anemia, heart failure) underwent compression ultrasonography (CUS) of proximal lower limb veins within 48 h from admission and at discharge to diagnose ADVT and SDVT. Covid-19 patients, anticoagulant therapy, surgical procedures, acute SDVT, and acute pulmonary embolism, were exclusion criteria. Biographical characteristics at hospitalization, D-Dimer (assessed by ELISA)) and DD-improve score. RESULTS: Of 2,100 patients (1002 females, 998 males, age 71 ± 16 years) 58 (2.7%) had proximal ADVT at admission. Logistic regression analysis showed that age, and active cancer were independently associated with ADVT at admission. The median length of hospitalization was 10 days [interquartile range: 6-15]. During the hospital stay, 6 patients (0.3%) with a negative CUS at admission experienced DVT (2 SDVT and 4 ADVT). In the subgroup of patients (n = 1118), in whom D-dimer was measured at admission, D-Dimer and IMPROVE-DD score were associated with ADVT at admission (n = 37) and with all DVT (n = 42) at discharge. ROC curve defined an IMPROVE-DD score of 2.5 as the optimal cut-off for discriminating patients with and without thrombotic events. CONCLUSIONS: We provide evidence of early development of ADVT in unselected acutely ill medical patients suggesting the need of investigating patients by CUS immediately after hospital admission (within 48 h). Advanced age, active cancer, known thrombophilia and increased IMPROVE-DD score may identify patients at risk. The benefit of anticoagulation needs to be investigated in patients with these specific risk factors and negative CUS at admission. TRIAL REGISTRATION: NCT03157843.

Thromboembolic Complications in COVID-19 Patients Hospitalized in Italian Ordinary Wards: Data from the Multicenter Observational START-COVID Register.

Background Coronavirus disease 2019 (COVID-19) infection causes acute respiratory insufficiency with severe interstitial pneumonia and extrapulmonary complications; in particular, it may predispose to thromboembolic disease. The reported incidence of thromboembolic complications varies from 5 to 30% of cases. Aim We conducted a multicenter, Italian, retrospective, observational study on COVID-19 patients admitted to ordinary wards, to describe the clinical characteristics of patients at admission and bleeding and thrombotic events occurring during the hospital stay. Results The number of hospitalized patients included in the START-COVID-19 Register was 1,135, and the number of hospitalized patients in ordinary wards included in the study was 1,091, with 653 (59.9%) being males and 71 years (interquartile range 59-82 years) being the median age. During the observation, two (0.2%) patients had acute coronary syndrome episodes and one patient (0.1%) had an ischemic stroke; no other arterial thrombotic events were recorded. Fifty-nine patients had symptomatic venous thromboembolism (VTE) (5.4%) events, 18 (30.5%) deep vein thrombosis (DVT), 39 (66.1%) pulmonary embolism (PE), and 2 (3.4%) DVT+PE. Among patients with DVT, eight (44.4%) were isolated distal DVT and two cases were jugular thrombosis. Among patients with PE, seven (17.9%) events were limited to subsegmental arteries. No fatal PE was recorded. Major bleeding events occurred in nine (1.2%) patients and clinically relevant nonmajor bleeding events in nine (1.2%) patients. All bleeding events occurred among patients receiving thromboprophylaxis, more frequently when treated with subtherapeutic or therapeutic dosages. Conclusion Our findings confirm that patients admitted to ordinary wards for COVID-19 infection are at high risk for thromboembolic events. VTE recorded among these patients is mainly isolated PE, suggesting a peculiar characteristic of VTE in these patients.

Lack of cross-reactivity between rheumatoid factor IgM and anti-S1 receptor binding domain of SARS-CoV-2 IgM: a case-control study.

OBJECTIVES: Since the onset of the COVID-19 outbreak, concern has been raised about reliability of SARS-CoV-2 serological tests in people with serum positivity for rheumatoid factor (RF), due to its ability to interfere during tests carried out with immunoassay techniques, leading to false positive results. The aim of this study was to analyse, on sera from RF seropositive rheumatoid arthritis (RA) patients, the interference between RF IgM and anti-S1 RBD IgM. METHODS: The study was conducted on consecutive patients affected by RF seropositive RA and, as control group, COVID-19 patients with SARS-CoV-2 pneumonia hospitalised at Sapienza University of Rome from April 2020 and April 2021. Serum samples from COVID-19 patients during their hospitalisation were collected, while RA subjects' samples were harvested prior to the onset of the COVID-19 pandemic. All samples were tested for RF IgM using nephelometry and ELIA, and for anti-S1 RBD IgM by ELISA. RESULTS: Forty RF seropositive RA and 42 COVID-19 patients were enrolled. In all RA patients, both nephelometric assay and ELIA showed RF IgM positivity, while only one patient of the control group tested positive for RF IgM by nephelometric assay and ELIA. IgM directed to S1 RBD were not detected in sera of RA patients, while all COVID-19 patients presented anti-S1 RBD IgM (median anti-S1 RBD IgM COVID-19 vs. RA: 368.5 IU/mL, IQR 654 IU/mL vs. 18.45 IU/mL, IQR 20 IU/mL; p<0.0001). CONCLUSIONS: This study confirmed the lack of cross-reactivity between RF and anti-S1 RBD IgM, offering to clinicians a valuable tool for a better management of RA patients undergoing SARSCoV-2 serological tests.

The ADA (Age-D-Dimer-Albumin) Score to Predict Thrombosis in SARS-CoV-2.

BACKGROUND: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-related pneumonia is associated with venous and arterial thrombosis. Aim of the study was to find out a new score for predicting thrombosis in patients with SARS-CoV-2. METHODS: We included a cohort of 674 patients affected by SARS-CoV-2, not requiring intensive care units, and followed-up during the hospitalization until discharge. Routine analyses performed at in-hospital admission included also serum albumin and D-dimer while arterial and venous thromboses were the endpoints of the study. RESULTS: During the follow-up, 110 thrombotic events were registered; patients with thrombotic events were older and had lower albumin and higher D-dimer, compared with thrombotic event-free ones. On multivariable logistic regression with step-by-step procedure age, serum albumin, and D-dimer were independently associated with thrombotic events. The linear combination of age, D-dimer, and albumin allowed to build-up the ADA (age-D-dimer-albumin) score, whose area under the curve (AUC) was 0.752 (95% confidence interval [CI], 0.708-0.795). ADA score was internally validated by bootstrap sampling procedure giving an AUC of 0.752 (95% CI: 0.708-0.794). CONCLUSION: Combination of age, D-dimer, and albumin in the ADA score allows identifying SARS-CoV-2 patients at higher risk of thrombotic events.

Comparison of Thrombotic Events and Mortality in Patients with Community-Acquired Pneumonia and COVID-19: A Multicenter Observational Study.

BACKGROUND: It is still unclear if patients with community-acquired pneumonia (CAP) and coronavirus disease 2019 (COVID-19) have different rate, typology, and impact of thrombosis on survival. METHODS: In this multicenter observational cohort study, 1,138 patients, hospitalized for CAP (n = 559) or COVID-19 (n = 579) from seven clinical centers in Italy, were included in the study. Consecutive adult patients (age ≥ 18 years) with confirmed COVID-19-related pneumonia, with or without mechanical ventilation, hospitalized from March 1, 2020 to April 30, 2020, were enrolled. COVID-19 was diagnosed based on the World Health Organization interim guidance. Patients were followed-up until discharge or in-hospital death, registering the occurrence of thrombotic events including ischemic/embolic events. RESULTS: During the in-hospital stay, 11.4% of CAP and 15.5% of COVID-19 patients experienced thrombotic events (p = 0.046). In CAP patients all the events were arterial thromboses, while in COVID-19 patients 8.3% were venous and 7.2% arterial thromboses.During the in-hospital follow-up, 3% of CAP patients and 17% of COVID-19 patients died (p < 0.001). The highest mortality rate was found among COVID-19 patients with thrombotic events (47.6 vs. 13.4% in thrombotic-event-free patients; p < 0.001). In CAP, 13.8% of patients experiencing thrombotic events died versus 1.8% of thrombotic event-free ones (p < 0.001). A multivariable Cox-regression analysis confirmed a higher risk of death in COVID-19 patients with thrombotic events (hazard ratio: 2.1; 95% confidence interval: 1.4-3.3; p < 0.001). CONCLUSION: Compared with CAP, COVID-19 is characterized by a higher burden of thrombotic events, different thrombosis typology and higher risk of thrombosis-related in-hospital mortality.

COVID-19 and thrombosis: Clinical features, mechanism of disease, and therapeutic implications.

COVID-19 is a viral respiratory illness caused by the SARS-CoV-2 infection. In addition to lung disease, clinical complications of COVID-19 include myocardial damage and ischemia-related vascular disease. Severe manifestations and poor prognosis in these patients are associated with a hypercoagulable state predisposing to thrombotic-related complications and eventually death. However, these clinical features can also occur in other forms of pneumonia, such as community-acquired pneumonia (CAP), which, is also complicated by vascular diseases and characterized by platelet activation. Platelets play a pivotal role in these settings as bacteria and viruses may induce activation via Toll-like receptors (TLRs) in CAP patients and different and multiple pathways, including ACE2-AngII axis and/or TLRs, in COVID-19 patients. Despite evidence confirming the implication of platelet activation in both settings, their contribution to the thrombotic process is still under investigation. Thus, in this review, we (1) compare the thrombotic features of SARS-CoV-2 infection and CAP, (2) analyze the putative mechanisms accounting for venous and arterial thrombosis in SARS-CoV-2 infection, and (3) discuss the potential anticoagulant armamentarium to counteract thrombosis.

Thrombosis in pre- and post-vaccination phase of COVID-19.

Acute infections may be complicated by thrombosis occurring in the venous and arterial circulation. This may be observed in patients with community-acquired pneumonia (CAP) and also in patients with coronavirus 2019 (COVID-19), that is a pandemic characterized by severe acute respiratory syndrome (SARS-CoV-2) needing mechanical ventilation and intensive care unit treatment. However, the type and rate of thrombosis can vary according to the cause of pneumonia as is more frequently complicated by arterial thrombosis in CAP, while an equal incidence of venous and arterial thrombosis occurs in SARS-CoV-2. The mechanisms of disease are overall platelet-related in CAP while activation of both platelets and clotting system is implicated in the pathogenesis of thrombosis in SARS-CoV-2; this finding could imply a different therapeutic approach of the two settings. Thrombosis may also occur in subjects vaccinated against SARS-CoV-2 even if its incidence is not so high (1/100 000); this rare effect occurs more prevalently in young women, is independent from known risk factors of thrombosis, is caused by antibodies against platelet PF4 and is counteracted by treatment with immunoglobulin and glucocorticoids.

Arterial and venous thrombosis in coronavirus 2019 disease (Covid-19): relationship with mortality.

BACKGROUND: Patients with coronavirus disease 2019 (Covid-19) may experience venous thrombosis while data regarding arterial thrombosis are sparse. METHODS: Prospective multicenter study in 5 hospitals including 373 patients with Covid-19-related pneumonia. Demographic data, laboratory findings including coagulation tests and comorbidities were reported. During the follow-up any arterial or venous thrombotic events and death were registered. RESULTS: Among 373 patients, 75 (20%) had a thrombotic event and 75 (20%) died. Thrombotic events included 41 venous thromboembolism and 34 arterial thrombosis. Age, cardiovascular disease, intensive care unit treatment, white blood cells, D-dimer, albumin and troponin blood levels were associated with thrombotic events. In a multivariable regression logistic model, intensive care unit treatment (Odds Ratio [OR]: 6.0; 95% Confidence Interval [CI] 2.8-12.6; p < 0.001); coronary artery disease (OR: 2.4; 95% CI 1.4-5.0; p = 0.022); and albumin levels (OR: 0.49; 95% CI 0.28-0.87; p = 0.014) were associated with ischemic events. Age, sex, chronic obstructive pulmonary disease, diabetes, heart failure, coronary heart disease, intensive care unit treatment, in-hospital thrombotic events, D-dimer, C-reactive protein, troponin, and albumin levels were associated with mortality. A multivariable Cox regression analysis showed that in-hospital thrombotic events (hazard ratio [HR]: 2.72; 95% CI 1.59-4.65; p < 0.001), age (HR: 1.035; 95% CI 1.014-1.057; p = 0.001), and albumin (HR: 0.447; 95% CI 0.277-0.723; p = 0.001) predicted morality. CONCLUSIONS: Covid-19 patients experience an equipollent rate of venous and arterial thrombotic events, that are associated with poor survival. Early identification and appropriate treatment of Covid-19 patients at risk of thrombosis may improve prognosis.

Thrombosis in Covid-19 and non-Covid-19 pneumonia: role of platelets.

Platelets may be a target of bacteria and viruses, which can directly or indirectly activate them so promoting thrombosis. In accordance with this, community-acquired pneumonia (CAP) is complicated by ischemia-related vascular disease (myocardial infarction and stroke) in roughly 10% of patients while the incidence of venous thrombosis is uncertain. In CAP platelet biosynthesis of TxA2 is augmented and associated with myocardial infarction; however, a cause-effect relationship is still unclear as unclear is if platelet activation promotes thrombosis or functional changes of coronary tree such vasospasm. Retrospective studies suggested a potential role of aspirin in reducing mortality but the impact on vascular disease is still unknown. Coronavirus disease 2019 (Covid-19) is complicated by thrombosis in roughly 20% of patients with an almost equivalent localization in arterial and venous circulation. Platelet activation seems to have a pivot role in the thrombotic process in Covid-19 as consistently evidenced by its involvement in promoting Tissue Factor up-regulation via leucocyte interaction. Until now, antiplatelet treatment has been scarcely considered for the treatment of Covid-19; interventional trials, however, are in progress to explore this issue. The aim of this review is 1) to compare the type of vascular diseases complicating CAP and Covid-19 2) to assess the different role of platelets in both diseases and 3) to discuss if antiplatelet treatment is potentially useful to improve clinical outcomes.

Low-Grade Endotoxemia and Thrombosis in COVID-19.

INTRODUCTION: Patients with community-acquired pneumonia display enhanced levels of lipopolysaccharides (LPS) compared with controls, suggesting that low-grade endotoxemia may be implicated in vascular disturbances. It is unknown whether this occurs in patients with coronavirus 2019 (COVID-19) and its impact on thrombotic complications. METHODS: We measured serum levels of zonulin, a marker of gut permeability, LPS, and D-dimer in 81 patients with COVID-19 and 81 healthy subjects; the occurrence of thrombotic events in COVID-19 during the intrahospital stay was registered. RESULTS: Serum LPS and zonulin were higher in patients with COVID-19 than in control subjects and, in COVID-19, significantly correlated (R = 0.513; P < 0.001). Among the 81 patients with COVID-19, 11 (14%) experienced thrombotic events in the arterial (n = 5) and venous circulation (n = 6) during a median follow-up of 18 days (interquartile range 11-27 days). A logistic regression analysis showed that LPS (P = 0.024) and D-dimer (P = 0.041) independently predicted thrombotic events. DISCUSSION: The study reports that low-grade endotoxemia is detectable in patients with COVID-19 and is associated with thrombotic events. The coexistence of low-grade endotoxemia with enhanced levels of zonulin may suggest enhanced gut permeability as an underlying mechanism.