Low Fibrinogen Levels Are Associated with an Increased Risk of Parenchymal Hematoma in Ischemic Stroke Treated with Intravenous Thrombolysis

<b>Background</b>: Intravenous thrombolysis (IVT), used in acute ischemic stroke (AIS), may be complicated by the development of intracranial hemorrhage. The role of fibrinogen levels, including their decrease, as a possible predictor of intracranial hemorrhage, has not yet been fully clarified. We aimed to evaluate the association between fibrinogen levels and their decrease 6 and 24 h after IVT and the risk of parenchymal hematoma (PH), as the clinically most significant type of intracranial hemorrhage. <b>Methods</b>: In an observational, nationwide, multicenter study, data from adult patients who underwent IVT for AIS from the Registry of Stroke Care Quality (RES-Q) in the Czech Republic (2019-2021) were analyzed. An association between fibrinogen levels and their decrease 6 and 24 h after IVT and the risk of PH was assessed. <b>Results</b>: We analyzed a set of 27 patients with PH (13 males; median age 78.0 years) and a control group (CG) of 97 patients without intracranial hemorrhage (58 males; median age 78.0 years). Fibrinogen levels 6 h after IVT (median 1.93 [PH] vs. 2.57 [CG] g/L, <i>p</i> = 0.012) and the ratio of baseline fibrinogen to fibrinogen 6 h after IVT (median 1.78 [PH] vs. 1.26 [CG]; <i>p</i> = 0.008) were associated with the development of PH. The optimal cut-off value of fibrinogen 6 h after IVT for predicting PH was <2.0 g/L. <b>Conclusions</b>: Fibrinogen levels 6 h after IVT and the ratio of baseline fibrinogen to fibrinogen 6 h after IVT are associated with an increased risk of PH in patients with acute ischemic stroke treated with IVT.