A guideline for the prevention and treatment of thromboembolism in COVID-19 patients

The coronavirus disease 2019 (COVID-19) was first emerged from Wuhan, China, in late 2019, and has since been spreading progressively all around the world. Its prevalence is climbing increasingly and almost all countries worldwide are confronting this pandemic. As of April 11, 2020, reports obtained about the management of COVID-19 patients indicate that the mortality rate of the disease is around 5% with consideration of the active cases and 21% of the closed cases (1). Preliminary experiences had indicated that the leading cause of death in COVID-19 patients was severe hypoxia following acute respiratory distress syndrome (2, 3); however, the gradually increasing information regarding the pathophysiology of the disease has shown that angiotensin-converting enzyme 2 (ACE2) is a cellular receptor for the severe acute respiratory syndromecoronavirus 2 (SARS-CoV-2) (4). The distribution of ACE2 receptor is widespread in the human body and is found in abundance in various tissue cells, including epithelial cells, vascular endothelial cells, kidney cells, brain tissue cells and etc. (5). Therefore, it is hypothesized that ARDS may not be the only cause of death in patients. Furthermore, recent findings demonstrating the inconsistency between the clinical manifestations of some patients with their imaging and laboratory findings has reinforced the mentioned hypothesis (3, 6). For instance, Zhou et al reported that 18% of non-severe cases and 3% of severe cases of COVID-19 had normal presentations in their chest radiography and computed tomography (CT) scans .