Thrombosis, especially venous thrombosis, is one of the serious complications that may occur in patients infected with the new coronavirus. To end them, special treatment is required. Hematologists are committed to determining the best therapeutic dose and preventing risks.
Pandemic SARS-CoV-2 It has caused unprecedented changes in national health systems around the world. Today, more than 102 million people have been infected and nearly 2 million have died.
In the first published Chinese study on infected patients Bilateral pneumonia, Describes changes in hemostasis that may cause Venous and arterial thrombotic diseases -That is, blood clots or thrombi have formed in both systems, mainly in those systems that require intensive care units.
These observations were later confirmed in a number of studies, and it is estimated that the pathological incidence of thrombosis in people with this disease has increased by 30%. Coronavirus disease.In addition to the classic risk factors, they are also described New mechanism This makes patients more susceptible to venous thromboembolic disease or VTE.
The severe clinical manifestations of covid-19 are acute respiratory distress syndrome, septic shock and coagulopathy. Its characteristics can be explained by the fact that SARS-CoV-2 (via angiotensin converting enzyme) infects two lung cells ( A special kind of cell that forms alveoli) and Vascular endothelial cells, This is your main goal.
Damage to the microvasculature has also been observed, accompanied by thickening of the vessel wall and formation of microthrombi. Similarly, changes in fibrinolytic function during lung inflammation lead to the accumulation of fibrin in the alveolar space. These findings may explain the high levels of D-dimer found in patients with severe COVID-19 (a sign of a dangerous blood clotting disorder), which is closely related to VTE and mortality.
Patient anticoagulation therapy
This heparinEspecially low-molecular-weight (LMWH) drugs have unique anti-fibrinolytic and anti-inflammatory properties, and have been selected as the best choice for the prevention of covid-19 VTE. Therefore, anticoagulation therapy has become the preferred anticoagulation therapy. Its preventive experience in routine use in hospitalized patients.
However, what is the best anticoagulant dose to prevent VTE?American Society of Hematology (ASH) and International Thrombosis and Hemostasis Association ((ISH) initially recommended in its guidelines that all patients admitted to the hospital with COVID-19 pneumonia should receive a “preventive dose” of LMWH.
However, given the patient’s certain additional risk of thrombosis or based on their D-dimer levels, various hospital procedures are more aggressive when using higher doses. Since then, different results have been obtained in several studies using medium-dose LMWH, but there is no conclusive evidence.
It is increasingly consistent that early use of LMWH in COVID-19 patients can reduce mortality, especially in patients with elevated D-dimer levels, not only by preventing VTE, but also by preventing at other levels VTE forms microthrombi to reduce mortality.
Therefore, it was recently published in ” British Medical Journal A sample of 4297 COVID-19 hospitalized patients demonstrated how the use of a preventive dose of LMWH 24 hours after hospitalization can reduce the 30-day mortality rate without increasing the risk of bleeding. However, because this is an observational study, the author warns against this limitation and concludes that only through random trials can conclusive evidence be extracted.
Contribution of hematology to covid-19
In parallel with previous work, ASH has published an update on the recommendations on the use of anticoagulants for the prevention of thrombosis in patients infected with SARS-CoV-2, and recommended the use of “preventive intensity-instead of moderate intensity or therapeutic-suitable for Severe COVID-19-related patients with no suspected or confirmed venous thromboembolism (conditional recommendation based on very low certainty of the evidence on the effect).
In addition, there are currently some ongoing clinical trials that compare the effects of preventive doses and intermediate doses of heparin on the prevention of VTE in this group of patients. Therefore, when we obtain the results of such studies, these recommendations may change.
This is one of the most important contributions made by hematology in the fight against covid-19. Of course, together with research on cell therapy (using the plasma of convalescent patients and mesenchymal cells), the similarities between SARS and CAR-T treatment of cytokine release syndrome, and the impact of pandemic Patients with diseases, especially those who suffer from hematological malignancies or who have undergone bone marrow transplantation.
Therefore, this new disease accounts for 16% of all communications received in the last time National Congress of Hematology, Blood Therapy, Thrombosis and Hemostasis, We actually celebrated in October last year.
Cristina Pascual Izquierdo Is the Spanish Society of Hematology and Hematology (SEHH) And work in the Department of Hematology and Blood Therapy Services of Gregorio Marañón University General Hospital.