MONITORING FIBRINOLYSIS WITH GLOBAL ASSAYS TO DETECT HYPER AND HYPOFIBRINOLYSIS PHENOTYPES

Abstract

Introduction: The fibrinolytic system is an important component of hemostasis that acts as a balance of blood coagulation to protect the vasculature from damaging thrombus formation. Monitoring fibrinolysis has been considered an emerging science, and recent studies show that fibrinolysis aids in the assessment of subgroups of critically ill patients at risk of bleeding and thrombotic complications. In this context, global tests to identify fibrinolytic potential have been developed, and knowledge about the performance of these tests is still limited. The aim of this study was to evaluate the performance of global fibrinolysis assays to detect hypo- and hyperfibrinolysis phenotypes. Method: In this study, samples from Healthy Individuals (HI), patients with hematologic Cancer (CA) and Venous Thrombosis (VTE), were obtained from the UNICAMP Hemocentro biobank. The methods assessed were: (1) Turbidimetric tPA-induced clot lysis time assay (tPA-CLT), (2) Turbidimetric tPA-induced clot lysis time assay with thrombomolulin (tPA-CLT-TM), (3) Plasmin generation test (PG). Demographic data, biochemical and coagulation tests, and clinical outcomes were collected. The study was part of the ISTH Reach the World Fellowship Program, in collaboration with the UNC Blood Research Center, Chapel Hill NC USA. Results: Plasmas from 107 individuals were evaluated in parallel: 30 CA, 25 VTE, and 52 HI matched by sex and age. The median age was 53 (21‒71), 48 (25‒72), 43 (19‒66), the male to female ratio was 15:15, 17:8, 34:18 for CA, VTE and HI, respectively. For tPA-CLT, only the median Onset-Time (min) was found to be higher for VTE when compared to HI, 6.0 and 5.3 (p 0.005); (2) VMax (mOD/Min) 526.80 and 386.40 (p < 0.0001); (3) Turbidity change 0.6851 and 0.5000 (p < 0.001); (4) AUC 4.085 and 3.060 (p < 0.05). The tPA-CLT-TM test showed the same pattern of results as the tPA-CLT test for VTE and CA. However, for CA the results showed even more significant differences in the same parameters, with the addition of Lysis Time (min) 26.84 and 19.33 (p < 0.001). PG presented 2/5 parameters with lower median for VTE compared to HI: (1) Onset-Time (min) 4.465 and 4.760 (p < 0.05) and (2) VMax (mOD/Min) 22.25 and 23.26 (p < 0.05). To PG, CA presented 3/5 parameters with lower median compared to HI: (1) VMax (mOD/Min) 20.58 and 23.26 (p < 0.001); (2) Peak (nM) 54.40 and 60.26 (p < 0.05); EPP (nM.min) 337.1 and 479.5 (p < 0.001). CA patients showed an association between tPA-CLT parameters and creatinine (p < 0.001) and eGRF was assessed. VTE patients showed an association of tPA-CLT parameters with LDL, Triglycerides (p < 0.05). Thrombin generation test and D-dimer were evaluated. Discussions and conclusions: The performance of global fibrinolysis tests was different between VTE, CA and HI. The tPA-CLT and tPA-CLT-TM assays proved to be sensitive for CA patients, suggesting faster, larger and heavier fibrin formation. In a more specific evaluation, CA showed lower plasmin generation. The tPA-CLT with the addition of thrombomodulin, as activator, had not yet been explored and was shown to favor the sensitivity of the test. The different performance of these tests could help identify hypo- and hyperfibrinolysis phenotypes, and thus contribute to the assessment of subgroups of critically ill patients at risk of bleeding and thrombotic complications.