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.

Thrombophilia and Immune-Related Genetic Markers in Long COVID.

Aiming to evaluate the role of ten functional polymorphisms in long COVID, involved in major inflammatory, immune response and thrombophilia pathways, a cross-sectional sample composed of 199 long COVID (LC) patients and a cohort composed of 79 COVID-19 patients whose follow-up by over six months did not reveal any evidence of long COVID (NLC) were investigated to detect genetic susceptibility to long COVID. Ten functional polymorphisms located in thrombophilia-related and immune response genes were genotyped by real time PCR. In terms of clinical outcomes, LC patients presented higher prevalence of heart disease as preexistent comorbidity. In general, the proportions of symptoms in acute phase of the disease were higher among LC patients. The genotype AA of the interferon gamma (IFNG) gene was observed in higher frequency among LC patients (60%; p = 0.033). Moreover, the genotype CC of the methylenetetrahydrofolate reductase (MTHFR) gene was also more frequent among LC patients (49%; p = 0.045). Additionally, the frequencies of LC symptoms were higher among carriers of IFNG genotypes AA than among non-AA genotypes (Z = 5.08; p < 0.0001). Two polymorphisms were associated with LC in both inflammatory and thrombophilia pathways, thus reinforcing their role in LC. The higher frequencies of acute phase symptoms among LC and higher frequency of underlying comorbidities might suggest that acute disease severity and the triggering of preexisting condition may play a role in LC development.

Role of Genetic Thrombophilia Markers in Thrombosis Events in Elderly Patients with COVID-19.

Thrombosis is an extremely dangerous complication in elderly patients with COVID-19. Since the first months of the pandemic, anticoagulants have been mandatory in treatment protocols for patients with COVID-19, unless there are serious contraindications. We set out to discover if genetic thrombophilia factors continue to play a triggering role in the occurrence of thrombosis in patients with COVID-19 with prophylactic or therapeutic anticoagulants. We considered the following genetic markers as risk factors for thrombophilia: G1691A in the FV gene, C677T and A1298C in the MTHFR gene, G20210A and C494T in the FII gene, and (-675) 4G/5G in the PAI-I gene. In a cohort of 176 patients, we did not obtain a reliable result indicating a higher risk of thrombotic complications when taking therapeutic doses of anticoagulants in carriers of genetic markers for thrombophilia except the C494T mutation in the FII gene. However, there was still a pronounced tendency to a higher incidence of thrombosis in patients with markers of hereditary thrombophilia, such as FV G1691A and FII G20210A mutations. The presence of the C494T (Thr165Met) allele in the FII gene in this group of patients showed a statistically significant effect of the mutation on the risk of thrombotic complications despite anticoagulant therapy.

Venous thromboembolism after COVID-19 vaccination in patients with thrombophilia.

Patients with thrombophilia remain concerned about venous thromboembolism (VTE) risk with COVID-19 vaccinations. The aim of this study was to examine VTE outcomes in patients with inherited or acquired thrombophilia who were vaccinated for COVID-19. Vaccinated patients ≥18 years between November 1, 2020 and November 1, 2021 were analyzed using electronic medical records across the Mayo Clinic enterprise. The primary outcome was imaging confirmed acute VTE occurring 90 days before and after the date of the first vaccine dose. Thrombophilia patients were identified through laboratory testing results and ICD-10 codes. A total of 792 010 patients with at least one COVID-19 vaccination were identified. Six thousand sixty-seven of these patients were found to have a thrombophilia, among whom there was a total of 39 VTE events after compared to 51 VTE events before vaccination (0.64% vs. 0.84%, p = .20). In patients with Factor V Leiden or prothrombin gene mutation, VTE occurred in 27 patients before and in 29 patients after vaccination (0.61 vs. 0.65%, p = .79). In patients with antiphospholipid syndrome, VTE occurred in six patients before and four patients after vaccination (0.59% vs. 0.39%, p = .40). No difference was observed in the overall VTE rate when comparing the postvaccination 90 days to the prevaccination 90 days, adjusted hazard ratio 0.81 (95% confidence interval: 0.53-1.23). In this subgroup of COVID-19 vaccinated patients with thrombophilia, there was no increased risk for acute VTE postvaccination compared to the prevaccination timeframe. These results are consistent with prior studies and should offer additional reassurance to patients with inherited or acquired thrombophilia.

Contribution of genotypes in Prothrombin and Factor V Leiden to COVID-19 and disease severity in patients at high risk for hereditary thrombophilia.

Thrombotic and microangiopathic effects have been reported in COVID-19 patients. This study examined the contribution of the hereditary thrombophilia factors Prothrombin (FII) and Factor V Leiden (FVL) genotypes to the severity of COVID-19 disease and the development of thrombosis. This study investigated FII and FVL alleles in a cohort of 9508 patients (2606 male and 6902 female) with thrombophilia. It was observed that 930 of these patients had been infected by SARS-CoV-2 causing COVID-19. The demographic characteristics of the patients and their COVID-19 medical history were recorded. Detailed clinical manifestations were analyzed in a group of cases (n = 4092). This subgroup was age and gender-matched. FII and FVL frequency data of healthy populations without thrombophilia risk were obtained from Bursa Uludag University Medical Genetic Department's Exome Databank. The ratio of males (31.08%; 27.01%) and the mean age (36.85 ± 15.20; 33.89 ± 14.14) were higher among COVID-19 patients compared to non-COVID-19 patients. The prevalence of FVL and computerized tomography (CT) positivity in COVID-19 patients was statistically significant in the thrombotic subgroup (p < 0.05). FVL prevalence, CT positivity rate, history of thrombosis, and pulmonary thromboembolism complication were found to be higher in deceased COVID-19 patients (p < 0.05). Disease severity was mainly affected by FVL and not related to genotypes at the Prothrombin mutations. Overall, disease severity and development of thrombosis in COVID-19 are mainly affected by the variation within the FVL gene. Possible FVL mutation should be investigated in COVID-19 patients and appropriate treatment should be started earlier in FVL-positive patients.

Downregulation of the Protein C Signaling System Is Associated with COVID-19 Hypercoagulability-A Single-Cell Transcriptomics Analysis.

Because of the interface between coagulation and the immune response, it is expected that COVID-19-associated coagulopathy occurs via activated protein C signaling. The objective was to explore putative changes in the expression of the protein C signaling network in the liver, peripheral blood mononuclear cells, and nasal epithelium of patients with COVID-19. Single-cell RNA-sequencing data from patients with COVID-19 and healthy subjects were obtained from the COVID-19 Cell Atlas database. A functional protein-protein interaction network was constructed for the protein C gene. Patients with COVID-19 showed downregulation of protein C and components of the downstream protein C signaling cascade. The percentage of hepatocytes expressing protein C was lower. Part of the liver cell clusters expressing protein C presented increased expression of ACE2. In PBMC, there was increased ACE2, inflammatory, and pro-coagulation transcripts. In the nasal epithelium, PROC, ACE2, and PROS1 were expressed by the ciliated cell cluster, revealing co-expression of ACE-2 with transcripts encoding proteins belonging to the coagulation and immune system interface. Finally, there was upregulation of coagulation factor 3 transcript in the liver and PBMC. Protein C could play a mechanistic role in the hypercoagulability syndrome affecting patients with severe COVID-19.

Thromboembolic events in deceased patients with proven SARS-CoV-2 infection: Frequency, characteristics and risk factors.

BACKGROUND: Infection with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) results in respiratory syndromes but also in vascular complications such as thromboembolism (TE). In this regard, immunothrombosis, resulting from inflammation in SARS-CoV-2 infected tissues, has been described. Data on TE in COVID-19 are mainly based on clinical observational and/or incomplete autopsy studies. The true burden of TE and the relevance of genetic predisposition, however, have not been resolved. OBJECTIVES: Here, we report on a consecutive cohort of 100 fully autopsied patients deceased by SARS-CoV-2 infections during the first wave of the pandemic (March to April 2020). We investigated the localization of TE, potential clinical risk factors, and the prothrombotic gene mutations, factor V Leiden and prothrombin G20210A, in postmortem blood or tissue samples. RESULTS: TE was found in 43/100 autopsies. 93 % of TE events were venous occlusions, with 23 patients having pulmonary thromboembolism (PT) with or without lower-extremity deep vein thrombosis. Of these, 70 % showed PT restricted to (sub)segmental arteries, consistent with in situ immunothrombosis. Patients with TE had a significantly higher BMI and died more frequently at an intensive care unit. Hereditary thrombophilia factors were not associated with TE. CONCLUSIONS: Our autopsy results show that a significant proportion of SARS-CoV-2 infected patients suffer from TE, affecting predominantly the venous system. Orthotopic peripheral PT was the most frequent finding. Hereditary thrombophilia appears not to be a determinant for TE in COVID-19. However, obesity and the need for intensive care increase the risk of TE in these patients.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V.

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.

Whole blood samples for faster real-time PCR analysis of thrombophilic mutations in SARS-CoV-2 virus positive patients.

High incidence of thrombosis and venous thromboembolism was reported in patients with COVID-19. In this study, we focused on analysis of thrombophilic mutations performed without a standard DNA extraction step. In one hundred of COVID-19 positive outpatients, real-time PCR for Leiden mutation in the FV gene and G20210A mutation in the FII gene was carried out from DNA extracts and modified whole blood samples, and their cycle threshold (Ct) values were evaluated. In the extracts, healthy homozygotes (wt/wt), heterozygotes (M/wt), and homozygous carriers of Leiden mutation (M/M) provided median Ct values of 18.5, 19.4/22.0, and 20.9. In the whole blood, Ct values were 25.3 (wt/wt), 24.8/27.2 (M/wt), and 26.9 (M/M). Median Ct values for G20210A in the extracts were 19.6 for homozygotes (wt/wt), and 19.7/20.4 for heterozygous carriers. The whole blood samples provided Ct values of 23.9 in healthy homozygotes and 26.3/27.2 in heterozygotes for G20210A mutation. No homozygous subjects for G20210A and no double heterozygotes (for Leiden and G20210A mutations) were found. Despite significant differences in the Ct values, genotyping showed complete result concordance of the DNA extracts and the whole blood samples. The integrity and amplificability of DNA molecules in the whole blood samples during 28 days of deep freezing, interrupted by four cycles of thawing, did not significantly change. In conclusion, we demonstrated a new protocol for the detection of the thrombophilic mutations via real time PCR on the modified whole blood of COVID-19 positive patients. The blood modification was reliable, easy, cheap, and saving costs and turnaround time of the whole laboratory process.