The Multiple Faces of Heparin: Opportunities in COVID-19 Infection and Beyond

COVID-19 and Long-COVID Thrombosis: From Clinical and Basic Science to Therapeutics

Coronavirus infectious disease-19 (COVID-19) is a pandemic characterized by serious lung disease and thrombotic events in the venous and circulation trees, which represent a harmful clinical sign of poor outcome. Thrombotic events are more frequent in patients with severe disease requiring intensive care units and are associated with platelet and clotting activation. However, after resolution of acute infection, patients may still have clinical sequelae, the so-called long-COVID-19, including thrombotic events again in the venous and arterial circulation. The mechanisms accounting for thrombosis in acute and long COVID-19 have not been fully clarified; interactions of COVID-19 with angiotensin converting enzyme 2 or toll-like receptor family or infection-induced cytokine storm have been suggested to be implicated in endothelial cells, leucocytes, and platelets to elicit clotting activation in acute as well in chronic phase of the disease. In acute COVID-19, prophylactic or full doses of anticoagulants exert beneficial effects even if the dosage choice is still under investigation; however, a residual risk still remains suggesting a need for a more appropriate therapeutic approach. In long COVID-19 preliminary data provided useful information in terms of antiplatelet treatment but definition of candidates for thrombotic prophylaxis is still undefined.

Direct Oral Anticoagulants Versus Vitamin K Antagonists for the Treatment of Left Ventricular Thrombi-Insights from a Swiss Multicenter Registry

Current guidelines recommend vitamin K antagonists (VKAs) for the treatment of a left ventricular thrombus (LVT). However, direct oral anticoagulants (DOACs) show superior safety and efficacy compared with VKAs in most thromboembolic disorders. Nevertheless, DOACs remain poorly investigated for the treatment of LVT. To describe the thrombus resolution rate and clinical efficacy of DOACs versus VKAs in patients with LVT, we analyzed consecutive patients with confirmed LVT from a multicenter echocardiography database. Echocardiograms and clinical end points were evaluated independently. The thrombus resolution rate and clinical outcomes were compared according to the underlying anticoagulation regimen. In total, 101 patients were included (17.8% women, mean age 63.3 ± 13.2 years), 50.5% had recently experienced a myocardial infarction. The mean left ventricular ejection fraction was 36.6 ± 12.2%. DOACs versus VKAs were used in 48 and 53 patients, respectively. The median follow-up was 26.6 (interquartile range 11.8;41.2) months. Among patients receiving VKAs compared with DOACs, the thrombus resolved more rapidly within the first month in those taking VKAs (p = 0.049). No differences were seen between the 2 groups with respect to major bleedings, strokes, and other thromboembolic events. In each group, LVT recurred in 3 of the subjects (a total of 6) after discontinuation of anticoagulation. In conclusion, DOACs appear to be a safe and effective alternative to VKAs for the treatment of LVTs, but the rate of thrombus dissolution within 1 month after initiation of anticoagulation appears to be higher with VKAs. A sufficiently powered randomized trial is required to definitively define the role of DOACs in the treatment of LVT.

Comparison of three methods including temperature, H2O2/ascorbic acid/sonication, and nitrous acid treatments for overcoming the inhibitory effect of heparin on DNA amplification in realtime-PCR

Heparin molecules have an inhibitory effect on DNA amplification by binding to the majority of DNA-interacting proteins. Different physical, chemical, and enzymatic methods have been used to degrade and depolymerize heparins in biomedical investigations. In this study, we aimed to evaluate some heparin degradation methods to eliminate the inhibitory effect of heparin on DNA amplification. Here, we report highly efficient, simple, and convenient methods to eliminate the heparin inhibitory effect on DNA amplification by treatments including temperature, nitrous acid, and H₂O₂/ascorbic acid/sonication. Further, treatment conditions including temperature degree and duration of treatments, the concentration of ascorbic acid, and intensity of sonication were reviewed. Target DNAs were extracted using the phenol-chloroform method. DNA concentrations and purity were analyzed before and after each treatment by Nanodrop spectrophotometry. DNA amplifications were attempted using a commercially available realtime-PCR mastermix. We found that the inhibitory behavior of heparin was well eliminated after the 85 °C/2 h, 65 °C/2 h, nitrous acid (pH = 3), and H₂O₂/ascorbic acid/sonication treatments, respectively. The further analyses indicated that the application of nitrous acid in pH = 1.5 and H₂O₂/ascorbic acid/sonication in higher ascorbic acid concentrations and sonication intensities lead to failure in DNA amplification due to the degradation of target sequences. From our experience, simple heat treatments or at the next level using nitrous acid and H₂O₂/ascorbic acid/sonication have enabled the detection and quantification of virus infection in heparin blood samples. These approaches may enable researchers to utilize blood taken in heparin tubes for genome amplification and diagnostic purposes.

Optimization of Heparin Monitoring with Anti-FXa Assays and the Impact of Dextran Sulfate for Measuring All Drug Activity

Heparins, unfractionated or low molecular weight, are permanently in the spotlight of both clinical indications and laboratory monitoring. An accurate drug dosage is necessary for an efficient and safe therapy. The one-stage kinetic anti-FXa assays are the most widely and universally used with full automation for large series, without needing exogenous antithrombin. The WHO International Standards are available for UFH and LMWH, but external quality assessment surveys still report a high inter-assay variability. This heterogeneity results from the following: assay formulation, designed without or with dextran sulfate to measure all heparin in blood circulation; calibrators for testing UFH or LMWH with the same curve; and automation parameters. In this study, various factors which impact heparin measurements are reviewed, and we share our experience to optimize assays for testing all heparin anticoagulant activities in plasma. Evidence is provided on the usefulness of low molecular weight dextran sulfate to completely mobilize all of the drug present in blood circulation. Other key factors concern the adjustment of assay conditions to obtain fully superimposable calibration curves for UFH and LMWH, calibrators' formulations, and automation parameters. In this study, we illustrate the performances of different anti-FXa assays used for testing heparin on UFH or LMWH treated patients' plasmas and obtained using citrate or CTAD anticoagulants. Comparable results are obtained only when the CTAD anticoagulant is used. Using citrate as an anticoagulant, UFH is underestimated in the absence of dextran sulfate. Heparin calibrators, adjustment of automation parameters, and data treatment contribute to other smaller differences.

Sulodexide in the Treatment of Patients with Early Stages of COVID-19: A Randomized Controlled Trial

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may induce several vascular endothelial-dependent systemic complications, and sulodexide has pleiotropic actions on the vascular endothelium, which may prove beneficial. We aimed to assess the effect of sulodexide when used within 3 days of coronavirus disease 2019 (COVID-19) clinical onset. We conducted a randomized placebo-controlled outpatient trial. To be included, patients must have been at high risk for severe clinical progression. Participants received sulodexide (oral 1,000 LRU/d) or placebo for 21 days. The primary endpoint was the need for hospital care. Also assessed were patients' need for supplemental oxygen as well as D-dimer and C-reactive protein (CRP) levels, thromboembolic events, major bleeding, and mortality. A total of 243 patients were included in the per-protocol analysis from June 5 to August 30, 2020. Of these, 124 received sulodexide and 119 received a placebo. Only 17.7% of the patients in the sulodexide group required hospitalization, compared with 29.4% in the placebo group (p = 0.03). This benefit persisted in the intention-to-treat analysis (15% in sulodexide group vs. 24% with placebo [p = 0.04]). With sulodexide, fewer patients required supplemental oxygen (30 vs. 42% [p = 0.05]). After 2 weeks, fewer patients had D-dimer levels >500 ng/dL (22 vs. 47% [p < 0.01]), and patients also had lower mean CRP levels (12.5 vs. 17.8 mg/dL [p < 0.01]). There were no between-group differences in thromboembolic events, major bleeding, or mortality. Treatment of COVID-19 patients with sulodexide, when provided within 3 days of clinical onset, improved their clinical outcomes. Although the results should be confirmed, sulodexide could be valuable in an outpatient setting.