key: cord-0986781-gwe8nkeh
authors: Daviet, Florence; Guervilly, Christophe; Baldesi, Olivier; Bernard-Guervilly, Fanny; Pilarczyk, Estelle; Genin, Adrien; Lefebvre, Laurent; Forel, Jean Marie; Papazian, Laurent; Camoin-Jau, Laurence
title: Heparin-Induced Thrombocytopenia in Severe COVID-19
date: 2020-09-29
journal: Circulation
DOI: 10.1161/circulationaha.120.049015
sha: 39f7cb72ce0542b68972b7181c103a667e88a0e2
doc_id: 986781
cord_uid: gwe8nkeh

nan

During the COVID-19 pandemic period, we admitted 86 patients with severe COVID-19 in 2 intensive care units, which represents an incidence of HIT of 8%. Although thrombocytopenia is frequent in critically ill patients, the incidence of HIT is relatively rare (<1% 3 ; up to 3.7% in patients supported by extracorporeal membrane oxygenation). 4 In a previously published cohort of 105 patients supported by venovenous extracorporeal membrane oxygenation, we reported an incidence of HIT of 2% 5 compared with 3 among 14 patients (21%) during the COVID-19 pandemic. We compared this cohort with a control cohort of patients in the intensive care units of our centers during a 6-month period from January 1 to June 1, 2019: 447 patients were admitted to our centers, with 58.8% of patients requiring mechanical ventilation and 13 patients (5%) supported by extracorporeal membrane oxygenation. During this period, 19 patients (4.2%) were tested for HIT, and 4 were ultimately positive, representing 0.89% of the cohort. The median rate of anti-PF4 among patients with HIT was 22.6, compared with 0.045 in HIT-negative patients. Regarding our results, we observed a nearly 10-fold higher occurrence of HIT during severe COVID-19 in our centers. This increased incidence could be explained by the higher doses of heparin used for treatment of patients with COVID-19 and by specific features of severe CO-VID-19 disease. Whereas obesity is associated with an increased risk of developing HIT, only 2 patients were obese in our observation.

The pathophysiology of an increased thrombosis risk or a potential increased HIT risk in the context of COVID-19 is not yet clearly understood. The higher prevalence of HIT in these patients could be explained by exacerbated immune reactions and probably by an increased release of PF4 linked to platelet activation.

Critically ill patients with COVID-19 develop lifethreatening coagulopathy and thromboembolic complications that justify aggressive anticoagulation with close monitoring. However, the occurrence of HIT increases the risk of severe thrombotic events and could alter the risk-benefit balance of anticoagulation. In this context, clinicians should be aware of a possible higher incidence of HIT. Achieving a 4T score (thrombocytopenia, timing of thrombocytopenia relative to heparin exposure, thrombosis or other sequelae of HIT, likelihood of other causes of thrombocytopenia) in patients with COVID-19 is complex. Thrombocytopenia and thrombosis are commonly observed, and patients present with other causes of thrombocytopenia. Rapid detection of antibodies to PF4/heparin is necessary in patients with COVID-19 to avoid a misdiagnosis of HIT. Immune dysregulation observed during acute CO-VID-19 may contribute to HIT occurrence. Further larger investigations are warranted to confirm this increased incidence of HIT and to understand its physiopathology.

Endothelial cell infection and endothelitis in COVID-19

Extremely high incidence of lower extremity deep venous thrombosis in 48 patients with severe COVID-19 in Wuhan

Heparin-induced thrombocytopenia in critically ill patients

Platelets and extra-corporeal membrane oxygenation in adult patients: a systematic review and meta-analysis

Prevalence and risk factors for thrombotic complications following venovenous extracorporeal membrane oxygenation: a CT scan study

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