notes by dr Claudio Italiano
vedi anche la profilassi della trombosi
Venous thromboembolism, ie the formation of thrombi, and therefore of blood coagulated within the veins, is a serious public health problem because it can cause hospital mortality between 5 and 10%, due to the risk of pulmonary embolism, that is they detach and become emboli that reach the pulmonary circle, causing a stop in a more or less important vessel of the lung. The prevalence of VTE is high in patients at risk, ie in:
For all these reasons a Congress of the International Society
on Thrombosis and Haemostasis was held in Geneva in July 2007, reaching the
following conclusions:
VTE is a global health problem
Prophylaxis can be implemented, ie to prevent the risk of embolism with adequate
antithrombotic treatment, with low molecular weight heparins, in particular
enoxaparin.
The study involved 370 hospital centers in 20 different countries, including Italy, and enrolled more than 5,000 medical patients with reduced mobility for more than three days following hospital admission. All patients underwent standard therapy with subcutaneous enoxaparin sodium 40 mg for ten days, which was maintained for 28 days or replaced with placebo. Three months later, a 44 percent reduction in the relative risk of venous thromboembolism was observed in patients who had benefited from an extension of therapy. In particular, a 73 percent reduction in symptomatic events of deep vein thrombosis and 34 percent of asymptomatic ones was recorded. The risk of bleeding was greater in these patients, however the events were rare and there was no difference in mortality from all causes after six months. At the international congress, the authors emphasized that EXCLAIM adds new evidence on the importance of the extension of enoxaparin sodium administration not only in surgical patients, but also in those with reduced mobility following hospitalization for heart failure, respiratory failure , inflammatory or oncological disease. "Prophylaxis in deep vein thrombosis should not only affect the hospital doctor but also the general practitioner, who is responsible for the management of his patient in the delicate post-hospital period". Prophylaxis of venous thromboembolism with low molecular weight heparin or unfractionated heparin is recommended in acute ischemic stroke, but there is uncertainty about the regimen being able to provide optimal treatment. The PREVAIL study (Efficacy and Safety of Enoxaparin Versus Infractionated Heparin for the Prevention of Venous Thromboembolism After Acute Ischaemic Stroke) compared the efficacy and safety of Enoxaparin (Clexane, Lovenox) with that of unfractionated heparin in patients with stroke. The study involved 1762 patients with acute ischemic stroke. These patients were randomly assigned within 48 hours of the onset of symptoms to receive Enoxaparin 40 mg subcutaneously 1 time / day or 5000 IU unparased subcutaneous Heparin every 12 hours for 10 days (range 6-14) . Patients were stratified by the NIHSS score (severe stroke: greater than or equal to 14, less severe stroke: less than 14). The primary efficacy composite endpoint included symptomatic or asymptomatic deep vein thrombosis, symptomatic pulmonary embolism or fatal pulmonary embolism. Primary safety endpoints were: symptomatic intracranial haemorrhage, major extracranial hemorrhage, and all-cause mortality. Enoxaparin (n = 666) and fractionated heparin (n = 669) were administered on average for 10.5 days. Enoxaparin reduced the risk of venous thromboembolism by 43% versus 8% of unfractionated heparin. The combined frequency of major extracranial hemorrhage and symptomatic intracranial hemorrhage was small and similar between the two groups (Enoxaparin 1% versus 1% unfractionated heparin). No difference was observed regarding symptomatic intracranial hemorrhage between groups (1% versus 1%, respectively).
The rate of major extracranial haemorrhage was higher in the Enoxaparin group than in the unfractionated Heparin group (1% versus 0%, p = 0.015). The results indicated that for patients with acute ischemic stroke, Enoxaparin is preferable to unfractionated Heparin for venous thromboembolism prophylaxis. (Xagena2007). Deep vein thrombosis prophylaxis of the patient of medical relevance: fondaparinux sodium, which is not a low molecular weight heparin, but a new molecule, a synthetic pentasaccharide that inhibits, binding to the antithrombin, the factor FXA (activated factor decino), is indicated at the dosage of 2.5 mg per day; for patients with renal impairment (where low molecular weight heparin should be monitored carefully) the dosage of fondaparinux is 1.5 mg / day (patients with a clearance between 20 and 50 ml / min). One of the main advantages of fondaparinux vs low molecular weight heparin is that it does not cause piastinopenia, because it does not bind to platelets and therefore the doctor is not obliged from a medico-legal point of view to dose the platelets. Furthermore, fondaparinux is indicated for the treatment of hemodynamically stable pulmonary embolism and of deep vein thrombosis at a dose of 7.5 mg subcutaneously once a day in patients weighing between 50 and 100 kg. In acute coronary syndrome, non-STEMI patients, see links on this site, and in the treatment of patients with unstable angina, fondaparinux reduced, compared to enoxaparin, mortality by 17% and reduced bleeding by more than 48% (OASIS-5 study , New England Journal of Medicine.The dosage used here is 2.5 mg / day.This study did change the ESC guidelines (European Society of Cardiology), recommendation grade 1A.