Highlights from

ISTH 2020

The International Society of Thrombosis and Haemostasis

Virtual 12-14 July 2020

COVID-19 not associated with heightened VTE risk after discharge

A study performed in Belgium revealed a rather low incidence of venous thromboembolism (VTE) in discharged COVID-19 patients, and so data do not warrant a recommendation for prescription of extended thromboprophylaxis on a regular basis [1].

As the use of low-molecular-weight heparin (LMWH) appears to be linked to a better prognosis for hospitalised COVID-19 patients, every COVID-19 patient at University Hospital Leuven receives LWMH at prophylactic dosage, with ICU patients receiving an intermediate dose [2]. Yet, limited evidence is available on the incidence of VTE in discharged patients after COVID-19 hospitalisation, and whether extended prophylactic therapy is necessary.

To this end, Dr Matthias Engelen (University Hospital Leuven, Belgium) and colleagues evaluated data from 133 adult COVID-19 patients. Participants were screened with venous ultrasound (VUS), and their C-reactive protein (CRP) and D-dimer levels were measured at 6 weeks after discharge. In high-risk patients, CT-pulmonary angiogram and ventilation/perfusion scans were also carried out. Mean age of the study subjects was 58 years, 63% were male, and the median length of hospitalisation lasted 10 days. Of the participants, 38% had been admitted to ICU, 60% needed mechanical ventilation, and 4% required extracorporeal membrane oxygenation (ECMO). Unsurprisingly, the median number of days spent in hospital was significantly longer for ICU patients (25 days) than non-ICU patients (7 days).

D-dimer levels generally increased during hospitalisation to maximum value, then significantly dropped before discharge, and were found significantly lower 6 weeks later. Distinguishing values for D-dimers between ICU and non-ICU patients showed higher levels for the ICU patients only while in hospital but not after discharge. Levels of CRP generally followed the same pattern as D-dimers, but lower levels of CRP in ICU patients at discharge were noticed, maybe attributable to their lengthier mean hospital stay.

Extended thromboprophylaxis was given to 38% of ICU and 13% of non-ICU patients only, leaving the greater part of COVID-19 patients without LMWH after discharge. Yet, no symptomatic VTE occurred in the study population after discharge and there was only 1 asymptomatic popliteal vein thrombosis. This equals a very low VTE rate of 0.8%, while the non-fatal bleeding rate during hospitalisation was 1.5%. "So, despite widely reported higher incidence of in-hospital VTE, we report very low incidence of VTE in patients discharged after COVID-19 hospitalisation in a centre with a high-dose prophylactic strategy and asymptomatic screening for all patients at follow-up in a well-defined ill population with rather low rates of extended thromboprophylaxis," Dr Engelen summarised the findings. This suggest that extended thromboprophylaxis of COVID-19 patients after hospitalisation is not routinely needed.

Keywords: COVID-19, Venous thromboembolism, VTE, SARS-CoV-2, Low-molecular-weight heparins, LMWH

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