Background: Anticoagulation with enoxaparin is recommended in acute pulmonary embolism (PE) and active cancer, and in patients who will receive vitamin K antagonists, who must overlap both drugs for several days. Pretreatment with enoxaparin during 5-10 days is needed in patients who will be treated with dabigatran or edoxaban. Usefulness of measuring Anti–Factor Xa activity (Anti-Xa) is uncertain since it´s unclear whether excessive or insufficient activity could be associated with higher bleeding or thrombotic risks, respectively.
Aims: Determine the existence of prognostic variables that could alter Anti-Xa in patients with PE anticoagulated with enoxaparin.
Methods: Single-center observational cohort registry. A total of 268 patients were hospitalized with PE between 2008-2018, and were eligible for this study those anticoagulated with enoxaparin in whom Anti-Xa was measured. The following prognostic factors were considered to establish variations in Anti-Xa: High-thrombus burden (H-ThB), right ventricular dysfunction, creatinine clearance < 50ml/min; obesity; active cancer and elderly.
Results: We included 126 patients; 59±16 years (51% female). Enoxaparin dose modifications ocurred in 39%.
Patients with H-ThB required more frequently dose modifications of enoxaparin (38% vs 17%; p:0.02) and were older (64 ±15 vs 56 ±16; p:0.01).
In patients who required dose modifications, 58% increased doses. No differences were observed between those who required dose modifications of enoxaparin vs those who didn´t, with regard to bleeding events (4.4 vs 3.8%), in-hospital mortality (2.1 vs 2.9%) and 30-day mortality (2.4 vs 5.3%), respectively. After multivariate analysis, only H-ThB was associated with dose modifications of enoxaparin (OR 2.9, 95%CI,1.03-8.71; p:0.04).
Conclusions: Measurement of Anti-Xa was useful in patients with PE anticoagulated with enoxaparin and H-ThB, since more than one third required modifications of the initial dose and of them, more than half increased the dose with similar bleeding rates. Likewise, thrombus burden quantification may be useful to guide treatment with enoxaparin.
To cite this abstract in AMA style:Bonorino J, Bilbao J, Fernandez H, Torres N, Iwanowski M, Alarcon P, Melchiori R, Santucci J, Aris Cancela ME, Colimodio P, Rosa C, Ferrario MC, Rubio P, Marquez S, Garcia G, Bivort M, Sanchez A, Perez Caceres N, Baratta S, Hita A. Usefulness of Measuring Anti–Factor Xa Activity to Guide the Treatment with Low-molecular-weight Heparins in Patients with Acute Pulmonary Embolism [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/usefulness-of-measuring-anti-factor-xa-activity-to-guide-the-treatment-with-low-molecular-weight-heparins-in-patients-with-acute-pulmonary-embolism/. Accessed September 27, 2023.
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