In Children with Provoked Venous Thromboembolism, Increasing Plasma Coagulability during the First 3 Months Postdiagnosis is Prognostic of Recurrence

Methods, precision, and analytical sensitivity of a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction

INTRODUCTION

Fibrinolysis is a critical aspect of the hemostatic system, with assessment of fibrinolytic potential being critical to predict bleeding and clotting risk. We describe the method for a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction (the "modified mini-euglobulin clot lysis assay [ECLA]"), its analytic sensitivity to alterations in key fibrinolytic substrates/regulators, and its initial applications in acute and convalescent disease cohorts.

METHODS

The modified mini-ECLA requires 50 μL of plasma, a maximal read time of 3 h (with most results available within 60 min), and is entirely performed in a 96-well microplate. Assay measurements were obtained in a variety of commercial control and deficient plasmas representing clinically relevant hypo- and hyperfibrinolytic states, and in three distinct adolescent cohorts with acute or convalescent illness: critically ill, following endotracheal intubation; acute COVID-19-related illness; and ambulatory, 3 months following a venous thromboembolic event.

RESULTS

In 100% and 75% deficient plasmas, hypofibrinolysis for plasminogen-deficient, fibrinolysis for alpha-2-antiplasmin-deficient, and hyperfibrinolysis for plasminogen activator inhibitor-1-deficient plasmas were observed.

CONCLUSION

The modified mini-ECLA Clot Lysis Time Ratio ("CLTR") demonstrated moderate-strength correlations with the Clot Formation and Lysis (CloFAL) assay, is analytically sensitive to altered fibrinolytic states in vitro, and correlates with clinical outcomes in preliminarily-studied patient populations.

Biomarkers in pediatric venous thromboembolism: a systematic review of the literature

BACKGROUND

Accurate prediction of the individual risk of venous thromboembolism (VTE) remains suboptimal in children, and biomarkers are currently not used to stratify the risk of VTE in children.

OBJECTIVES

This study aimed to assess which biological or radiological biomarkers may predict VTE or VTE complications in children.

PATIENTS/METHODS

A literature search was performed for peer-reviewed publications (1990-2022). We included studies addressing the use of biomarkers for patients aged 29 days to 18 years to predict VTE or its complications, including but not limited to TE-related death, VTE recurrence, or postthrombotic syndrome. Given the heterogeneity of the study designs, populations, and outcomes, no quantitative data synthesis was performed.

RESULTS

Forty studies were included, totaling 10,987 participants (median age: 4.7 years). Reports were often lacking critical methodological data, including blood collection method (68% of studies) and timepoints, laboratory testing technique (41%), or primary outcome definition (20%). Forty-six individual biomarkers were assessed for VTE prediction (32 studies, 9525 participants), including d-dimers, fibrinogen, platelet count, white blood cell count, and factor VIII. Albumin, C-reactive protein, d-dimers, factor VIII, and thrombin-antithrombin levels showed promising results for VTE prediction. In 9 studies (1606 participants), no biomarker was consistently predictive of postthrombotic syndrome, VTE persistence, or VTE recurrence in children.

CONCLUSIONS

Several candidate biomarkers were promising in the prediction of VTE in children. Still, discrepancies between different studies and the high risk of bias from the current literature prevent their widespread use in the clinical setting. Further prospective research in various pediatric subpopulations is required.

Thromboprophylaxis for children hospitalized with COVID-19 and MIS-C

Background

Limited data exist about effective regimens for pharmacological thromboprophylaxis in children with acute coronavirus disease 2019 (COVID‐19) and multisystem inflammatory syndrome in children (MIS‐C).

Objectives

Study the outcomes of institutional thromboprophylaxis protocol for primary venous thromboembolism (VTE) prevention in children hospitalized with acute COVID‐19/MIS‐C.

Methods

This single‐center retrospective cohort study included consecutive children (aged less than 21 years) with COVID‐19/MIS‐C who received tailored intensity thromboprophylaxis, primarily with low‐molecular‐weight heparin, from April 2020 through October 2021. Thromboprophylaxis was given to those with moderate to severe disease based on the World Health Organization scale and exposure to two or more VTE risk factors. Therapeutic intensity was considered for severe illness. Clinical recovery along with D‐dimer improvement determined thromboprophylaxis duration. Outcomes were incident VTEs, bleeding, and mortality.

Results

Among 211 hospitalizations, 45 (21.3%) received thromboprophylaxis (COVID‐19, 16; MIS‐C, 29). Median age was 14.8 years (interquartile range [IQR], 8.9–16.1). Among 35 (77.8%) with severe illness, 27 (60.0%) required respiratory support, and 19 (42.2%) required an intensive care unit stay. Median hospitalization was 6 days (IQR, 5.0–10.5). Median thromboprophylaxis duration was 19 days (IQR, 6.0–31.0) with therapeutic intensity in 24 (53.3%) and prophylactic in 21 (46.7%). Outcomes were as follows: VTE, 1 (2.2%); death, 1 (2.2%, unrelated to bleeding/thrombosis); major/clinically relevant nonmajor bleeding, 0; and minor bleeding, 7 (15.5%). D‐dimer was elevated in a majority at diagnosis (median, 2.3; IQR, 1.2–3.3 mg/ml fibrinogen‐equivalent units) and was noninformative in assessing disease severity. D‐dimer normalized at thromboprophylaxis discontinuation.

Conclusions

Our experience of using clinically directed thromboprophylaxis with tailored intensity approach for children hospitalized with COVID‐19 and MIS‐C favors its inclusion in current standard of care. The role of D‐dimer in directing thromboprophylaxis management deserves further evaluation.

SARS-COV-2-associated coagulopathy and thromboembolism prophylaxis in children: A single-center observational study

BACKGROUND

Multiple investigators have described an increased incidence of thromboembolic events in SARS-CoV-2-infected individuals. Data concerning hemostatic complications in children hospitalized for COVID-19/multisystem inflammatory syndrome in children (MIS-C) are scant.

OBJECTIVES

To share our experience in managing SARS-CoV-2-associated pro-coagulant state in hospitalized children.

METHODS

D-dimer values were recorded at diagnosis in children hospitalized for SARS-CoV-2-related manifestations. In moderately to critically ill patients and MIS-C cases, coagulation and inflammatory markers were checked at multiple time points and median results were compared. Pro-thrombotic risk factors were appraised for each child and thromboprophylaxis was started in selected cases.

RESULTS

Thirty-five patients were prospectively enrolled. D-dimer values did not discriminate COVID-19 of differing severity, whereas were markedly different between the COVID-19 and the MIS-C cohorts. In both cohorts, D-dimer and C-reactive protein levels increased upon clinical worsening but were not accompanied by decreased fibrinogen or platelet values, with all parameters returning to normal upon disease resolution. Six patients had multiple thrombotic risk factors and were started on pharmacological thromboprophylaxis. No deaths or thrombotic or bleeding complications occurred.

CONCLUSIONS

COVID-19 pediatric patients show mildly altered coagulation and inflammatory parameters; on the other hand, MIS-C cases showed laboratory signs of an inflammatory driven pro-coagulant status. Universal anticoagulant prophylaxis in hospitalized children with SARS-CoV-2-related manifestations is not warranted, but may be offered to patients with other pro-thrombotic risk factors in the context of a multi-modal therapeutic approach.