Venous thrombotic events in severe and critically COVID-19 patients despite high dose prophylactic low-molecular-weight heparin.

Hypercoagulation is one of the most distinct prognostic factors of patients with COVID-19 and has been associated with arterial thrombosis and other venous thrombotic events (VTE). Bleeding complications are far less encountered. The International Society on Thrombosis and Haemostasis (ISTH) guidance advises giving prophylactic low-molecular-weight heparin (LMWH) to prevent these events, although there is evidence that the incidence remains high despite using prophylactic LMWH. We describe three cases of COVID-19 pneumonia that were admitted to our intensive care unit (ICU) and developed acute pulmonary embolisms (APE) despite high dosage prophylactic LMWH. These cases raise concerns about using prophylactic LMWH instead of therapeutic anticoagulation in severe and critically COVID-19 patients.