Anticoagulation in COVID-19: not strong for too long?

A Delphi consensus on the management of anticoagulation in the COVID-19 pandemic: the MONACO study

Background

During the COVID-19 pandemic, guideline documents on the management of anticoagulation were rapidly published. However, these documents did not follow a structured methodology, and significant differences existed between the guidelines. The aim of this expert consensus was to provide recommendations on the clinical management of oral anticoagulation in patients in the context of the COVID-19 pandemic.

Methods

A two-round Delphi study was conducted using an online survey. In the first round, panellists expressed their level of agreement with the items on a 9-point Likert scale. Items were selected if they received approval from ≥66.6% of panellists and if they were agreed by the scientific committee. In the second round, panellists revaluated those items that did not meet consensus in the first round.

Results

A total of 147 panellists completed the first round, and 144 of them completed the second round. Consensus was reached on 161 items included in five dimensions. These dimensions addressed: (I) management of anticoagulation in patients with atrial fibrillation (AF) without mechanical valves or moderate/severe mitral stenosis during COVID-19 infection; (II) thromboprophylaxis in patients hospitalised for COVID-19; (III) management of anticoagulation at hospital discharge/after COVID-19; (IV) anticoagulation monitoring in the COVID-19 pandemic setting; and (V) role of telemedicine in the management and follow-up of patients with AF in the COVID-19 pandemic setting.

Conclusions

These areas of collective agreement could specially guide clinicians in making decisions regarding anticoagulation in patients with COVID-19 during hospitalisation and at discharge, where results from clinical trials are still limited and, in some cases, conflicting.

Platelet dysfunction and thrombus instability in flow conditions in patients with severe COVID-19

Severe COVID-19 has been associated with a high rate of thrombotic events but also of bleeding events, particularly when the level of prophylactic anticoagulation was increased. Data on the contribution of platelets to these thrombotic events are discordant between reports, while the involvement of platelets in bleeding events has never been investigated. The objective of the present study was to assess platelet function during the first week of ICU hospitalization in patients with severe COVID-19 pneumonia. A total of 35 patients were prospectively included and blood samples were drawn on day (D) 0, D2 and D7. COVID-19 pneumonia was severe with a median PaO₂/FiO₂ ratio of 91 [68-119] on D0. Platelets from these patients showed evidence of pre-activation and exhaustion with a significant reduction in the surface expression of GPVI, GPIb and GPIIbIIIa, together with a decrease in serotonin content. Platelets from patients with severe COVID-19 were hyporesponsive with a reduced maximal aggregation response to several platelet agonists and decreased adhesion to immobilized fibrinogen. Aggregation of washed platelets and plasma substitution experiments indicated that a plasma factor was at least partially responsible for this hyporeactivity of platelets. Blood flow experiments showed that severe COVID-19 platelets formed smaller, less stable aggregates on a collagen-coated surface, which could explain why some patients develop bleeding events. These findings should prompt us to carefully evaluate the risks and benefits of high-dose prophylactic anticoagulation, and to decrease the level of anticoagulation once the initial phase of the disease has resolved. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04359992.

Intermediate-to-therapeutic versus prophylactic anticoagulation for coagulopathy in hospitalized COVID-19 patients: a systemic review and meta-analysis

Background

Anticoagulation in hospitalized COVID-19 patients has been associated with survival benefit; however, the optimal anticoagulant strategy has not yet been defined. The objective of this meta-analysis was to investigate the effect of intermediate-to-therapeutic versus prophylactic anticoagulation for thromboprophylaxis on the primary outcome of in-hospital mortality and other patient-centered secondary outcomes in COVID-19 patients.

Methods

MEDLINE, EMBASE, and Cochrane databases were searched from inception to August 10th 2021. Cohort studies and randomized clinical trials that assessed the efficacy and safety of intermediate-to-therapeutic versus prophylactic anticoagulation in hospitalized COVID-19 patients were included. Baseline characteristics and relevant data of each study were extracted in a pre-designed standardized data-collection form. The primary outcome was all-cause in-hospital mortality and the secondary outcomes were incidence of thrombotic events and incidence of any bleeding and major bleeding. Pooled analysis with random effects models yielded relative risk with 95 % CIs.

Results

This meta-analysis included 42 studies with 28,055 in-hospital COVID-19 patients totally. Our pooled analysis demonstrated that intermediate-to-therapeutic anticoagulation was not associated with lower in-hospital mortality (RR=1.12, 95 %CI 0.99-1.25, p=0.06, I²=77 %) and lower incidence of thrombotic events (RR=1.30, 95 %CI 0.79-2.15, p=0.30, I²=88 %), but increased the risk of any bleeding events (RR=2.16, 95 %CI 1.79-2.60, p<0.01, I²=31 %) and major bleeding events significantly (RR=2.10, 95 %CI 1.77-2.51, p<0.01, I²=11 %) versus prophylactic anticoagulation. Moreover, intermediate-to-therapeutic anticoagulation decreased the incidence of thrombotic events (RR=0.71, 95 %CI 0.56-0.89, p=0.003, I²=0 %) among critically ill COVID-19 patients admitted to intensive care units (ICU), with increased bleeding risk (RR=1.66, 95 %CI 1.37-2.00, p<0.01, I²=0 %) and unchanged in-hospital mortality (RR=0.94, 95 %CI 0.79-1.10, p=0.42, I²=30 %) in such patients. The Grading of Recommendation, Assessment, Development, and Evaluation certainty of evidence ranged from very low to moderate.

Conclusions

We recommend the use of prophylactic anticoagulation against intermediate-to-therapeutic anticoagulation among unselected hospitalized COVID-19 patients considering insignificant survival benefits but higher risk of bleeding in the escalated thromboprophylaxis strategy. For critically ill COVID-19 patients, the benefits of intermediate-to-therapeutic anticoagulation in reducing thrombotic events should be weighed cautiously because of its association with higher risk of bleeding.

Trial registration

The protocol was registered at PROSPERO on August 17th 2021 (CRD42021273780).

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00343-1.