Blood. 2022 Apr 22:blood.2021012247. doi: 10.1182/blood.2021012247. Online ahead of print.
Infection with the SARS-CoV-2 virus, resulting in COVID-19 disease has presented a unique scenario associated with high thrombotic rates. The risk of venous thrombosis is some 3-6 fold higher than for patients admitted to hospital for other indications and for patients who have thrombosis, mortality appears increased. Thrombosis may be a presenting feature of COVID-19. Pulmonary thrombi are the most frequent events, some related to deep vein thrombosis, but also in situ micro- and macrovascular thrombosis. Other venous thromboses include catheter and circuit-associated in patients requiring haemofiltration and ECMO. Arterial thrombosis is less commonly documented, with 3% of ICU patients having major arterial strokes and up to 9% myocardial infarction, which is likely multifactorial. Risk factors for thrombosis above those already documented in hospital settings include duration of COVID-19 symptoms before admission to hospital. Laboratory parameters associated with higher thrombotic risk include higher D-dimer, low fibrinogen and low lymphocyte count, with higher FVIII and von Willebrand factor levels indicative of more severe COVID-19 infection. All patients should receive thromboprophylaxis when admitted with COVID-19 infection, but the dose and length of treatment still remain debated. Treatment for thrombosis remains as per standard VTE guidelines, but adjustments may be required depending on other factors relevant to the patient admission.