Bleeding and Bleeding Risk in COVID-19.

Abstract

Coronavirus disease 2019 (COVID-19) is a new, emerging medical challenge worldwide, with those affected showing a variety of clinical presentations, ranging from asymptomatic or mild conditions to critical illness. Patients affected by the causative virus—severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—usually experience cough, fever, dyspnea, myalgia, less frequently gastrointestinal (GI) manifestations and, rarely, neurological complications. Coagulopathy is common among those afflicted and appears to be one of the most significant adverse prognostic signs.[1] [2] Coagulopathy results from concomitant activation of coagulation and fibrinolytic systems, most likely due to a severe proinflammatory state (i.e., the so-called cytokine storm) and/or by viral sepsis that sometimes leads to consumption of coagulation factors and decreased platelet count, resulting in thrombohemorrhagic events.[3] In this process, plasmin breaks down fibrin present in plasma and the bronchoalveolar lavage fluid, as well as potentially other organs, and leading to excess D-dimer/fibrin(ogen) degradation product (FDP) formation. This may also lead to reduction in platelet count and increased risk for hemorrhage.[4] In a systematic review of 6,892 patients and meta-analysis of 3,496 patients, platelets were low in 22.9% and D-dimer was high in 34.8%; D-dimer was associated with a severe clinical course with an odds ratio (OR) of 4.03, and low platelets with an OR of 1.78.[5] Disseminated intravascular coagulation (DIC) in COVID-19 is accompanied by a significant decrease of fibrinogen, and a marked increase of FDP and D-dimer, which are characteristics of DIC with hyperfibrinolysis, whereas the DIC caused by infection is accompanied by plasminogen activator inhibitor-1 release and suppression of fibrinolysis. Administration of antiproteases may prove beneficial.[6] Elevated D-dimer, and FDP, often mildly prolonged prothrombin time and mildly decreased platelet counts were also reported as common findings by Tang et al, more common and more profound in severely affected patients.[2] Fibrinogen levels are sometimes lowered, but may instead be elevated, while activated partial thromboplastin time is sometimes prolonged, but may instead be shortened, with these potentially suggestive of acute phase events.[2] [6] Although hypercoagulability and thrombotic events are common in COVID-19, bleeding may occur at any time during the course of disease. Several factors make patients with COVID-19 prone to bleeding, including thrombocytopenia, hyperfibrinolytic state, consumption of coagulation factors, and thromboprophylaxis administration of anticoagulants. A proposed cytokine storm, prolonged tissue hypoxia, and direct invasion of affected tissues are other possible causes.[2] [7] [8] Although thrombosis is relatively well studied in COVID-19, bleeding and bleeding risk appear to be the forgotten side of this story, most probably due to the less-fatal consequences; however, hemorrhagic diatheses represents a significant morbidity and potential cause of death in COVID-19 in at least in a subset of patients.[7] [8]