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.