Abstract
Venous thromboembolic (VTE) events have been increasingly reported in patients with coronavirus disease 2019 (COVID-19) after hospital discharge. Acute pulmonary embolism (PE) is the most frequent type of post-discharge VTE complication. Levels of procoagulants (fibrinogen, factor VIII, von Willebrand factor), and D-dimer are higher during the SARS-CoV-2 infection. Patients with more severe inflammatory and procoagulant response experience higher VTE rates during hospitalization, while the risk after hospital discharge have not been well characterized. The incidence of VTE events following hospitalization is heterogeneous, ranging from low (3.1 per 1000 discharges), to 1.8%, which appears higher than for other medical condition. This discrepancy was partially explained by the differences in VTE screening and follow-up strategies, and by the period when the information about the VTE was collected. These data were based mainly on observational and retrospective studies; however, evolving data are to come after the completion of the prospective trials. The current guidelines do not recommend routine post-hospital VTE prophylaxis for COVID-19 patients but recommend it for all hospitalized adults. A careful risk-benefit assessment of VTE probability should be performed, to determine whether an individual patient may merit post-discharge thromboprophylaxis. A score such IMPROVE DD can help identify the patient who will potentially benefit but is also important to consider the bleeding risk and the feasibility. The optimal duration and the type of extended thromboprophylaxis is still under debate (from a minimum of 14 days to a maximum of 42 days), and future studies will help to validate these protocols in different populations. Direct oral anticoagulants (DOACs), warfarin and low molecular weight heparin (LMWH) are recommended, but low doses of DOACs rather than LMVH or warfarin were predominantly used in most patients. Finally, the COVID-19 patients should be educated to recognize and advised to seek urgent medical care should VTE events occur after hospital discharge.